What Does Mcv Mean In A Blood Test?

Contents

- 0.0.1 What does it mean if your MCV is high?
0.1 What does it mean when your MCV is low?

1 What level of MCV is concerning?
- 1.1 Should I worry if my MCV is low?
- 1.2 Should I be worried if my MCV is high?
2 When should I be worried about high MCV?
3 What is the MCV by age?
4 Does high MCH mean liver disease?
5 How does high MCV make you feel?
- - 5.0.1 Does dehydration cause high MCV?
- 5.1 What cancers cause high MCH levels?
6 What level of MCH is concerning?
- - 6.0.1 What medications cause high MCV?
  - 6.0.2 How do you fix a high MCV?
7 How do you treat high MCV?
- - 7.0.1 Does high MCV mean iron deficiency?
8 Can you have high MCV without anemia?

What does it mean if your MCV is high?

INTRODUCTION – High mean corpuscular volume (MCV), also known as macrocytosis, is associated with vitamin B12 and folic acid deficiency, liver disease, hyperglycemia, alcoholism, smoking habits, and other pathologic conditions, Moreover, a high MCV is associated with increased all-cause mortality and cancer mortality in non-anemic cancer-free individuals, Pulse wave velocity (PWV) is one of various markers of early arterial wall changes such as arterial wall thickness and stiffness, It is defined as the velocity of blood streaming from the heart to peripheral arteries through the aorta and is known to increase with blood vessel stiffness, Brachial-ankle pulse wave velocity (baPWV) is also strongly correlated with aortic PWV and can be used as a simple, noninvasive, and automatic method to measure arterial stiffness in the primary care setting, Previous studies have shown that increased PWV is independently associated with cardiovascular disease (CVD) incidence and mortality. Moreover, high baPWV was a strong predictor of early carotid atherosclerosis, A baPWV of >1,400 cm/s is an independent risk factor for moderate risk (≥10%) stratification according to the Framingham risk scoring system, and a baPWV of >1,600 cm/s is an independent factor for high risk stratification according to the European systematic coronary risk evaluation (SCORE) system, Although high MCV has been implicated in various health problems, the clinical significance of borderline-high MCV is poorly understood among apparently healthy Korean individuals in the primary care setting. Therefore, this study aimed to examine whether borderline-high MCV is related to arterial stiffness in Korean adults as measured using baPWV.

What does it mean when your MCV is low?

Interpreting test results – MCV test results are interpreted by comparing your MCV to a reference range, or the set of values that the laboratory expects for a healthy person. Reference ranges are based on the results of a large sample of healthy people and are associated with the equipment and procedures of the laboratory that conducts the test.

MCV is usually reported in femtoliters (fL).
The American Board of Internal Medicine lists a typical MCV reference range as 80-98 fL.
MCV levels are reported as within the reference range if they fall within the expected range for a healthy individual.
If the MCV result is outside of the reference range, it may be reported as high or low.

If you have anemia or other health conditions you can have normal or abnormal MCV results. It is also possible for healthy people to have a normal or abnormal MCV result. In patients with anemia, MCV results are categorized as follows:

Low MCV means that RBC are smaller than normal and may indicate microcytic anemia. This condition may be caused by iron deficiency, lead poisoning, or thalassemia, a genetic condition that causes your body to have less hemoglobin than normal.
Normal MCV may indicate normocytic anemia. This can occur when an individual experiences symptoms of anemia due to sudden blood loss, kidney failure, or aplastic anemia, a rare disorder where the body does not produce enough RBC.
High MCV means that the RBC are too large and indicates macrocytic anemia. This condition can be caused by several factors including low folate or vitamin B12 levels or chemotherapy.

MCV is usually not interpreted as an isolated measurement. Rather, it is compared to the results of your other RBC indices and CBC values, like hemoglobin and hematocrit. Your doctor will also consider any symptoms or changes in your health when interpreting these test results.

What do my MCV levels indicate about my health?
Can any diagnoses be made based on my MCV results?
Do I need any follow-up tests based on my MCV results?
If my MCV test results come back abnormal, is there anything you would suggest to improve my health?

Blood Smear Learn More
CBC Blood Test (Complete Blood Count) Learn More
MCH Blood Test (Mean Corpuscular Hemoglobin) Learn More
MCHC Blood Test (Mean Corpuscular Hemoglobin Concentration) Learn More
Platelet Count (PLT) Blood Test Learn More
Red Blood Cell Count (RBC) Test Learn More
White Blood Cell Count (WBC Blood Test) Learn More

What level of MCV is concerning?

Other causes – Other factors that may contribute to vitamin B12 and vitamin B9 deficiencies include:

chestfeedingconsuming too much alcohol tapeworm Crohn’s diseasecancer treatment medications

If someone is frequently tired and feels cold all the time, they may have anemia. People experiencing symptoms of anemia should contact a doctor. A doctor may ask about a person’s family’s medical history. Some conditions that cause anemia, such as thalassemia and Crohn’s disease, run in families.

An MCV test measures the size and volume of red blood cells.
A normal MCV range is roughly 80–100 fl,
If someone’s MCV level is below 80 fl, they will likely develop or have microcytic anemia.
Alternatively, if their MCV levels are greater than 100 fl, they could experience macrocytic anemia.
People with microcytic anemia may feel the cold more and look paler than usual.

People with macrocytic anemia may experience jaundice. If someone has symptoms of anemia, they should contact a doctor for advice. Usually, treating the underlying cause of the anemia alleviates symptoms. Read this article in Spanish,

Should I worry if my MCV is low?

Should I worry if my MCV is low? – How serious microcytosis becomes depends on what’s causing the condition. A low MCV can be alarming if it’s alongside symptoms of poisoning, specifically lead, which inhibits iron absorption, On the other hand, it can also be due to anemia, which can generally be treated by supplementation and diet adjustment.

Should I be worried if my MCV is high?

A high MCV means your red blood cells are larger than normal. While a high MCV can be associated with a group of cancers called myelodysplastic syndromes, other causes of high MCV, such as vitamin deficiency or liver disease, are far more common. A measurement of mean corpuscular volume (MCV) is included in a complete blood count (CBC),

A CBC is a common blood test that measures the numbers, types, and sizes of different blood cells. Having a high MCV means your red blood cells are larger than typical red blood cells. While a high MCV has many common causes, it can also be a sign of myelodysplastic syndromes, a group of cancers that affect blood.

In this article, we take a closer look at MCV, its association with cancer, and the health conditions that more commonly cause high MCV. An MCV test measures the average size of your red blood cells (RBCs), RBCs are the cells that transport oxygen to the organs and tissues of your body.

Normal: The normal range for MCV is 80 to 100 femtoliter (fL). This means your RBCs are a typical size. RBCs that fall into this range are called normocytic. Low: A low value for MCV is anything under 80 fL. This means your RBCs are smaller than normal. The term for this is microcytic. High: A high MCV value is anything over 100 fL. Having a high MCV means your RBCs are larger than normal. The term for this is macrocytic.

Myelodysplastic syndromes (MDS) are a group of cancers sometimes associated with high MCV. The American Cancer Society estimates that about 10,000 people in the United States receive a diagnosis of MDS each year, although this number may be higher. MDS happens when immature blood cells in the bone marrow become abnormal and have trouble developing into mature cells.

These abnormal cells die early, meaning your body doesn’t have enough healthy blood cells. This possibly results in lower than normal blood counts on blood work. Since MDS affects the blood cells of the bone marrow, the RBCs, white blood cells, and platelets can all be affected. RBCs are one cell type that can be involved in MDS.

Cells impacted by MDS can have dysplasia, which means they have an abnormal size, shape, or number. When MDS affects RBCs, it can lead to anemia. In fact, anemia is the most common finding in MDS. Several other conditions can cause a high MCV. Some of the most common include vitamin B12, folate, and copper deficiencies.

a lack of vitamin B12 in your dietimpaired absorption of vitamin B12, which can occur from:

certain autoimmune diseases

inflammatory bowel disease (IBD)

previous stomach surgery medications for acid reflux or diabetes, such as metformin

There are also several potential causes of folate deficiency, including:

a lack of folate in your dietheavy alcohol use factors affecting your gastrointestinal (GI) tract, such as:

celiac disease

IBD

previous GI surgery

pregnancy medications, such as methotrexate, some antibiotics, and some seizure medications

Other causes of high MCV that may be unrelated to a vitamin B12 or folate deficiency include:

alcohol use disorder liver disease MDS and multiple myeloma, which both cause rouleaux formation, a linking or clumping of RBCsunderactive thyroid ( hypothyroidism )medications, such as methotrexate, sulfasalazine, and certain HIV drugs HIV infection Down syndrome

Sometimes high MCV does not need to be treated. This is typically the case if all of the following are true:

MCV is less than 115 fLyou don’t have anemiathere are no other health concerns related to your MCV or other test results

High MCV that’s concerning or is causing symptoms is typically treated by addressing the condition that’s causing it. For example, supplementation can treat vitamin B12 or folate deficiencies. If you have cancer and a high MCV, your care team will develop a treatment plan for that cancer.

It’s possible your MCV values will return to the normal range with treatment. MCV measures the size of your RBCs. A high MCV means your RBCs are larger than normal, a condition called macrocytosis, Some people with high MCV have anemia, A high MCV can be associated with MDS, an uncommon type of cancer.

It affects cells in the bone marrow, including RBCs. However, it’s more likely that high MCV values are due to other causes, such as liver disease, heavy alcohol use, certain medications, or deficiencies in vitamins like B12, copper, and folate. It’s important to talk with a doctor if you have symptoms of anemia.

When should I be worried about high MCV?

What is a normal MCV in children? – Mean corpuscular volume (MCV) is an indicator of anemia and other blood disorders. Learn about normal ranges for children according to age group Mean corpuscular volume (MCV) is a measurement of the average size of red blood cells (RBCs). MCV is part of complete blood count —a routine screening test that analyzes the other two blood components, white blood cells, and platelets.

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Table: Normal MCV ranges for children by age group


Age	MCV range (in fL)
0 to 1 month	88 to 123
1 to 3 months	91 to 112
3 to 6 months	74 to 108
6 months to 1 year	70 to 85
2 to 3 years	74 to 89
4 to 6 years	77 to 91
7 to 10 years	78 to 92
11 to 14 years	80 to 95
15 to 18 years	81 to 96

What is the MCV by age?

3.4. Linear regression analysis of MCV and age – The age‐wise changes in the median MCV value are shown in Figure 3B and the Table S2, We obtained two linear regression equations for the relationship of MCV with age. The linear relationship for patients aged 1–25 years had a larger slope than that for patients aged 26–88 years. (A) Linear regression in male patients aged 1–25 years. (B) Linear regression in male patients aged 26–88 years (A) Linear regression in female patients aged 1–25 years. (B) Linear regression in female patients aged 26–88 years

Can low vitamin D cause low MCV?

3.1. Comparisons – Table 2 describes the computed differences of all determined parameters in groups I, II and III. There were only significant variations of vitamin D, MCV and MCHC between groups I, II and III. The increase of MCHC was significant lower, when vitamin D values went down, in comparison to the MCHC rise, when vitamin D was elevated.

Can stress cause elevated MCV?

Abstract – Some recent reports showed that a brief exposure to a mental stressor during 3-20 min may induce hematological changes in humans. The aim of the present study was to examine the effects of academic examination stress on erythron variables, such as the number of red blood cells (RBC), hemoglobin (Hb), hematocrit (Ht), mean corpuscular volume (MCV), mean cell Hb (MCH), mean cell Hb concentration (MCHC), RBC distribution width (RDW), and serum iron and transferrin (Tf).

The above variables were determined in 41 students in three conditions, i.e. the stress condition (the day before a difficult oral exam) and two baseline conditions, i.e. a few weeks earlier and later. At the same occasions, subjects completed the Perceived Stress Scale (PSS), the state version of the State-Trait Anxiety Inventory (STAI) and the Profile of Mood States (POMS).

Academic examination stress significantly increased Ht, Hb, MCV, MCH and MCHC and significantly decreased RDW. There were significant relationships between the stress-induced changes in the PSS, STAI and POMS scores and those in Ht, Hb, MCV and MCH (allpositive) and RDW (negative).

How do you treat high MCV?

What causes enlarged red blood cells (macrocytosis)? – Answer From Rajiv K. Pruthi, M.B.B.S. Macrocytosis is a term used to describe red blood cells that are larger than normal. Also known as megalocytosis or macrocythemia, this condition typically causes no signs or symptoms and is usually detected incidentally on routine blood tests.

Vitamin B-12 deficiency
Folate deficiency
Liver disease
Alcoholism
Hypothyroidism
A side effect of certain medications, such as those used to treat cancer, seizures and autoimmune disorders
Increased red blood cell production by the bone marrow to correct anemia, for example, after blood loss
An underlying bone marrow cancer called myelodysplastic syndrome

If you have macrocytosis, blood tests can help determine its cause. In some cases, it may be necessary to remove a sample of your bone marrow — the spongy tissue inside your bones — for testing. Management of macrocytosis consists of finding and treating the underlying cause.

Does high MCH mean liver disease?

Symptoms of low MCH levels – Share on Pinterest A loss of regular stamina and tiredness may be symptoms of low MCH levels. At first, many people with low MCH levels do not experience symptoms at all. When low MCH numbers persist or fall too low, symptoms start to appear. Symptoms of low MCH include:

shortness of breathloss of regular staminaconsistent tiredness dizzinessweakness in the body

Low MCH numbers can also affect the skin. The skin may become pale or bruise very easily in someone with low MCH levels. Anyone experiencing these symptoms should contact their doctor immediately. High MCH scores are commonly a sign of macrocytic anemia.

liver diseasesan overactive thyroid glanddrinking alcohol regularlycomplications from certain cancers complications from an infectiontaking too many medications containing estrogen

How long does it take for MCV to return to normal?

Hematogical Markers of Alcoholism – An important focus of alcohol research is the search for biological markers that could be used in simple screening tests to identify people who are at risk for alcoholism or who already are chronic heavy drinkers. Two categories of biological markers exist: state markers, which reflect a person’s alcohol consumption, and trait markers, which indicate a predisposition for alcoholism.

State markers fall into two main groups: screening markers and relapse markers. Screening markers, which detect chronic alcohol consumption, could complement information obtained from patients in the course of taking their medical history. This physical information could provide important diagnostic clues because, as clinical observations suggest, many people do not accurately report their level of alcohol consumption.

Thus, screening markers could be useful in the early identification of alcoholism, especially in patients who consume alcohol in amounts that do not lead to acute medical problems but that could have long-term behavioral or medical consequences. In contrast, relapse markers, which are sensitive to acute alcohol consumption, could play an important role in monitoring recovering alcoholics and other heavy drinkers.

State markers that would permit the identification of heavy drinkers even when alcohol is no longer present in the blood would be particularly valuable diagnostic tools. Trait markers could help identify people at risk for alcoholism who could benefit most from early, targeted prevention and intervention approaches.

These high-risk populations most prominently include first-degree relatives of alcoholics. Trait markers also could provide important research tools for evaluating the genetic and environmental factors that may predispose a person to alcoholism. State Markers Chronic ingestion of large quantities of alcohol alters many physiological and biological processes and compounds, including several blood-related (i.e., hematological) variables.

Because blood samples are relatively easy to obtain, structural and functional changes in circulating blood cells and plasma proteins potentially can form the basis of laboratory tests for screening, diagnosing, and monitoring alcoholism. Two hematological state markers commonly used for these purposes are the presence of carbohydrate-deficient transferrin (CDT) in the blood and an increase in the size of red blood cells (RBC’s), as measured by the mean corpuscular volume (MCV).

Carbohydrate-Deficient Transferrin, CDT is one of the newest—and perhaps the most promising—of the hematological state markers. Transferrin is an iron-containing protein in the plasma that transports iron, which is stored at various sites in the body, to the developing RBC’s in the bone marrow for incorporation into hemoglobin.

Transferrin molecules in the blood usually contain several carbohydrate components.
In chronic heavy drinkers, however, the number of carbohydrate components in each transferrin molecule is reduced, resulting in CDT.
The mechanism underlying this alteration still is unclear.
Because elevated CDT levels in the blood appear to be a specific consequence of excessive alcohol consumption, a recent study investigated the utility of repeatedly monitoring serum CDT to detect relapse among recovering alcoholics.

The study found that in most of the subjects who relapsed, the elevation of CDT levels preceded self-reported alcohol consumption by at least 28 days. These findings suggest that repeated testing of alcoholic patients for CDT permits early relapse detection and thus may lead to early intervention.

Early intervention, in turn, may decrease the need to rehospitalize patients for alcohol withdrawal and prevent some of the complications associated with sustained excessive drinking.
Mean Corpuscular Volume,
The MCV is elevated in approximately 50 to 60 percent of people who chronically ingest excessive alcohol quantities.

With the advent of automated instruments that determine the MCV during routine blood counts, physicians and other health care providers frequently detect elevated MCV’s in patients who are well nourished and who have no obvious disorders to explain this finding.

In these patients, a moderately increased MCV may be a clue to unsuspected alcoholism.
Analysis of blood smears can support this diagnosis: In patients with an alcohol-related increase in MCV, the enlarged RBC’s are round and of uniform size.
Conversely, in patients with certain types of anemia that result in an increased MCV, the RBC’s typically are oval and of variable size.

Because the MCV usually returns to normal within 2 to 4 months of abstinence, the increase in RBC size apparently is a direct effect of alcohol on RBC production. Trait Markers Researchers have proposed numerous genetic and genetically determined biochemical characteristics that might potentially serve as trait markers of alcoholism.

Because of the easy availability of blood samples, many research efforts have focused on biochemical markers that can be found in circulating blood platelets. These studies have identified two enzymes that appear to be viable markers of alcoholism and whose activities can be measured in isolated platelets: monoamine oxidase (MAO) and adenylyl cyclase (AC).

Monoamine Oxidase, MAO is an enzyme that breaks down certain neurotransmitters (e.g., dopamine and serotonin) that have been implicated in mediating various phenomena related to the risk of developing alcoholism (e.g., tolerance to alcohol’s effects).

Although MAO acts primarily in the brain, platelets also contain the enzyme.
MAO activity levels are genetically determined, and many studies have demonstrated that people with a certain alcoholism subtype or with particular psychiatric disorders (e.g., schizophrenia and mood disorders) exhibit abnormally low MAO activity levels.

In fact, low MAO activity in the platelets and other tissues of certain alcoholics is the most replicated biological finding in genetic alcoholism research. The available data also suggest that low MAO activity in the platelets predicts a risk for alcoholism in relatives of a certain type of alcoholics.

This alcoholism subtype is characterized by an early age of onset of alcohol-related problems, frequent social and legal consequences of drinking, and a strong genetic predisposition. Adenylyl Cyclase, AC is an enzyme that plays a role in the transmission of signals from a cell’s exterior to its interior; the enzyme’s levels in the body are genetically determined.

Several studies have found that AC levels in the platelets as well as in some white blood cells are frequently reduced in alcoholics compared with nonalcoholics, even after long periods of abstinence. Because a single gene appears to determine the level of platelet AC activity, it is likely that low platelet AC activity is an inherited trait in many alcoholics and therefore could be used as a trait marker.

What is the most common cause of low MCV?

Main types of anemia classified based on red cell morphology and their common causes – The common causes of microcytic and hypochromic anemia (decreased MCV and MCH) are as follows:

Thalassemia

The common causes of macrocytic anemia (increased MCV) are as follows:

Folate deficiency anemia
Vitamin B12 deficiency anemia
Liver disease
Hemolytic anemias
Hypothyroidism
Excessive alcohol intake

The common causes of normocytic and normochromic anemia (normal MCV) are as follows:

Acute blood loss
Hemolytic anemia, such as autoimmune hemolytic anemia, hereditary spherocytosis, or nonspherocytic congenital hemolytic anemia (G6PD deficiency, other)
Anemia of renal disease

Of note, when considering the causes of anemia, the guidelines above are helpful but have limitations. For example, hemolytic anemia and aplastic anemia can manifest as normochromic and normocytic anemia or macrocytic anemia; anemia of chronic disease can be normochromic and normocytic anemia or microcytic anemia; sideroblastic anemia can be microcytic anemia, macrocytic anemia, or normochromic and normocytic anemia (due to the presence of dimorphic population of microcytes and macrocytes).

What cancers cause low MCV?

low MCV without anaemia and cancer risk GPnotebook no longer supports Internet Explorer. To ensure the site functions as intended, please upgrade your browser. Microsoft is encouraging users to upgrade to its more modern for improved security and functionality.

risks were independent of any anaemia precise role of microcytosis in primary care across all cancers is not currently known, particularly in patients without anaemia

Microcytosis as an indicator for possible cancer has also been examined via a cohort study of patients aged >= 40 years using UK primary care electronic patient records (5):

1-year cancer incidence was compared between cohorts of patients with a mean red cell volume of <85 femtolitres (fL) (low) or 85-101 fL (normal). Further analyses examined sex, age group, cancer site, and haemoglobin values of 12 289 patients with microcytosis, 497 had a new cancer diagnosis within 1 year (4.0%, 95% confidence interval = 3.7 to 4.4), compared with 1465 of 73 150 without microcytosis (2.0%, CI = 1.9 to 2.1)

in males, 298 out of 4800 with microcytosis were diagnosed with cancer (6.2%, CI = 5.5 to 6.9), compared with 940 out of 34 653 without (2.7%, CI = 2.5 to 2.9) in females with microcytosis, 199 out of 7489 were diagnosed with cancer (2.7%, CI = 2.3 to 3.1), compared with 525 out of 38 497 without (1.4%, CI = 1.3 to 1.5) in patients with microcytosis but normal haemoglobin, 86 out of 2637 males (3.3%, CI = 2.6 to 4.0) and 101 out of 5055 females (2.0%, CI = 1.6 to 2.4) were diagnosed with cancer cancer sites that made up a greater proportion of cancers diagnosed in the microcytosis cohort than the normal cohort were: colorectal (113, 23%), lung (67, 13%), lymphoma (24, 5%), kidney (22, 4%), and stomach (15, 3%)

study authors concluded that microcytosis is a predictor of underlying cancer even if haemoglobin is normal. Although a benign explanation is more likely, clinicians in primary care should consider simple testing for cancer on encountering unexplained microcytosis, particularly in males

Summary suggested diagnostic workup (5):

for GPs, an MCV is only reported alongside the haemoglobin value

anaemia accompanied by microcytosis strongly suggests iron deficiency, and therefore measurement of iron stores would be the usual next step

if iron deficiency is identified, its cause will be sought, which would generally involve testing for gastrointestinal blood loss this diagnostic pathway does not remove the need to enquire about other symptoms suggestive of the malignancies reported here, particularly lung cancer

patients with microcytosis but without anaemia

some may be iron deficient, simplifying the investigation strategy seems sensible for all these patients to be also offered faecal immunochemical testing for hidden gastrointestinal blood loss, and a chest X-ray if respiratory symptoms suggest lung cancer is possible

Reference:

Shephard E et al. Quantifying the risk of non-Hodgkin lymphoma in symptomatic primary care patients aged ≥40 years: a large case-control study using electronic recordsBr J Gen Pract2015 Stapley S et al. The risk of oesophago-gastric cancer in symptomatic patients in primary care: a large case-control study using electronic records Br J Cancer 2013;108:12531 Hamilton W et al. The importance of anaemia in diagnosing colorectal cancer: a case-control study using electronic primary care records Br J Cancer 2008;82:323-327 Shephard E et al. Clinical features of kidney cancer in primary care: a case-control study using primary care recordsBr J Gen Pract2013 Hopkins R et al. Microcytosis as a risk marker of cancer in primary care: a cohort study using electronic patient records. Br J Gen Pract 2020; 70 (696): e457-e462

: low MCV without anaemia and cancer risk

Is it better to have high or low MCV?

Frequently Asked Questions –

What does high MCV in a blood test indicate? A high mean corpuscular volume (MCV) in a blood test indicates that red blood cells are larger than average. The presence of large blood cells is referred to as macrocytosis. What causes macrocytic anemia? Anemia is when a person has a low red blood cell count. There are two types of macrocytic anemias :

Megaloblastic macrocytic anemia is often caused by a deficiency of vitamin B12. Non-megaloblastic macrocytic anemia is caused by certain diseases including myelodysplastic syndrome (MDS), alcoholism, liver disfunction, hypothyroidism, and more.

How long does it take for MCV to return to normal? The underlying reason for high or low MCV levels will determine when, or if, it’s possible for them to return to normal. With treatment for a vitamin B12 deficiency, it takes about a month. If it’s due to alcohol use, it returns to normal if a person stops drinking. Your healthcare provider can give you information about what to expect.

How does high MCV make you feel?

What causes macrocytosis? – Problems with red blood cell production in your bone marrow (where blood cells are made) and structural problems with your red blood cells can lead to macrocytosis. You may have a high MCV because you have a lot of immature red blood cells (reticulocytes) in your blood. Reticulocytes are larger than fully mature red blood cells. Causes of macrocytosis include:

Nutritional deficiencies : Your body needs nutrients, like vitamin B12 and folate (vitamin B9), to make healthy red blood cells. Your red blood cells may not develop normally if you’re not consuming enough of these nutrients or if a condition is preventing your body from absorbing them. Deficiencies in vitamin B12 and folate cause macrocytic anemia. Medications : Multiple medicines can lead to macrocytosis. The most common types include a medicine for sickle cell disease called hydroxyurea, various chemotherapy drugs for cancer treatment and antiretroviral therapy (ART) for treating HIV, Alcohol use disorder : Drinking too much alcohol can prevent your body from absorbing the nutrients needed to make healthy red blood cells. Liver disease : Macrocytosis may be a sign of liver disease. Often — but not always — liver disease is related to consuming too much alcohol. Hemolytic anemia : With hemolytic anemia, an underlying condition causes your red blood cells to die too soon. When this happens, your body may release reticulocytes into your bloodstream to compensate. These immature red blood cells aren’t fully formed enough to successfully transport oxygen like mature red blood cells. Severe blood loss : Your body may release reticulocytes into your bloodstream if you lose large volumes of blood. As with hemolytic anemia, your body may release immature blood cells early to compensate for the lost blood cells. Myelodysplastic syndrome : This type of cancer prevents your bone marrow from producing healthy red blood cells. Hypothyroidism : People with this condition may have macrocytosis, with or without anemia.

Sometimes, macrocytosis doesn’t have a clear cause. This is especially the case if you have macrocytosis but don’t have anemia.

Does dehydration cause high MCV?

Increased MCV (macrocytosis) –

A rtifact

Red cell clumping or agglutination : With impedance-based analyzers, agglutinated RBC are detected as single large cells, resulting in very high MCVs (> 90 FL) and low MCHCs. This occurs rarely with the laser-based analyzers, such as the hematology analyzer we use at Cornell, since the agglutinated clumps are excluded from the analysis (which may decrease the RBC count but does not affect the MCV as much). Storage-related changes : Red blood cells swell with storage, increasing the MCV and decreasing MCHC. This will occur quite rapidly, within 24 hours of collection particularly if the blood sample is not kept cool until analysis. We have observed increases in MCV into the 60s (reference interval, 43-55 fL) in horses in mailed-in samples. The increases in MCV will falsely increase the HCT, which is a calculated value (see above formula). Hyperosmolality: With the ADVIA hematology analyzer (and potentially other hematologic analyzers), macrocytosis can be observed in animals with severe hyperosmolality, e,g. hypernatremia. This is attributed to dehydration of red blood cells which occurs in vivo due to the hyperosmotic environment. Once these dehydrated cells are placed in an iso-osmolar diluent for counting within the analyzer, they are now actually hypertonic compared to the diluent and swell in vitro in the iso-osmolar diluent, thus increasing the MCV and decreasing the MCHC. So the swelling of RBCs occurs in the machine and not in the animal.

Physiologic

Breed: Breed-associated macrocytosis has been reported in Greyhounds (around 81 fL, although this has recently been refuted ( Zaldivar-Lopez et al., 2011 ) and Miniature and Toy Poodles (up to 90 fL), without any evidence of anemia. Fetal RBC: Fetal RBC are macrocytic. These are generally rapidly removed after birth (phagocytized by macrophages) but some species, e.g. foals, can be macrocytic immediately after birth.

Pathophysiologic

Regenerative anemia : Since young red blood cells are usually larger, the MCV can be increased above reference intervals (and the MCHC decreased). These findings are less apparent with laser-based hematology analyzers. Cats that have recovered from a recent anemia can be macrocytic, since punctate reticulocytes (which are frequently larger than normal red blood cells) can persist for up to 3 weeks in the circulation. This is called a post-regenerative macrocytosis. Red cell swelling due to membrane abnormalities:

Hereditary stomatocytosis : This inherited defect has been reported in Alaskan, Malamutes, Miniature Schnauzers, Pomeranians, Drentsche Patrijshond and other breeds. There are breed-specific membrane defects in lipid content or the sodium/potassium pump, resulting in macrocytic and hypochromic red blood cells. Affected animals may not be anemic.

Defects in nuclear maturation/DNA synthesis

Primary myelodysplasia or myelodysplastic syndrome: This is a clonal (neoplastic) disorder, that in cats, is usually caused by feline leukemia virus infection. This virus intercalates with DNA, causing abnormal (delayed) nuclear maturation. Folate or vitamin B12 deficiency: Both are required for DNA synthesis (thymidine and nucleoproteins). Impaired DNA synthesis delays cell division resulting in macrocytosis. These deficiencies can occur with intestinal disorders and small intestinal bacterial overgrowth (although macrocytosis is not a feature of these diseases in dogs), drugs which inhibit folate/vitamn B12 absorption or metabolism (e.g. trimethoprim sulphur, hydroxyurea) or because of other mineral deficiencies or excess, such as cobalt deficiency (primary or secondary to molybdenum excess) in ruminants. Cobalt is essential in the molecular structure of vitamin B12.

Inherited abnormalities in erythropoiesis: Congenital dyserythropoietic anemia (CDA) is an inherited defect in humans that results in macrocytosis. This has been reported in Polled Hereford cattle and is likely the cause of macrocytosis in Poodles (despite the lack of anemia). Unknown mechanism or miscellaneous: Hyperthyroidism has been associated with macrocytosis in cats in some studies. This was attributed to thyroid hormone induced red blood cell production, with decreased maturation time and premature release of larger red blood cells. Similarly diabetes mellitus has been associated with increased MCV, but this may be a consequence of RBC swelling from osmolality changes. Most dogs and cats with hyperthyroidism or diabetes mellitus are not macrocytic.

MCV changes

What cancers cause high MCH levels?

High MCH Levels – An MCH level above 31 picograms/cell is considered abnormally high. This is most commonly associated with the following conditions:

Certain types of kidney diseases, including kidney cancer
Congenital heart defects
Lung disease, such as chronic obstructive pulmonary disease (COPD) and pulmonary fibrosis
Polycythemia vera, a rare blood disease typically caused by a genetic mutation where the bone marrow produces too many red blood cells
A side effect of certain medications (e.g., anabolic steroids)
Living in a high-altitude region

People with high MCH levels may have symptoms including:

Blood clots
Blurred or double vision
Dizziness
Headaches
Itching

What level of MCH is concerning?

Symptoms of High MCH – If you have high MCH due to anemia, you might experience symptoms of the anemia. For both folate- and vitamin B12–deficiency anemia, that can include fatigue, weakness, headache, and paleness. With folate–deficiency anemia, you may experience sore mouth and tongue.

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High and low MCH levels are treated differently based on which disease or medical condition is causing the abnormal levels. A healthcare provider will first have to determine why your MCH levels are low or high. They will likely look at the other results of your complete blood count for a full picture. There are other measurements of your red blood cells’ health:

Mean corpuscular volume (MCV): Measures of the average size of your red blood cells Mean corpuscular hemoglobin concentration (MCHC): Measures the amount of hemoglobin a red blood cell has relative to the cell’s volume Red cell distribution width (RDW) : Measures differences in the volume and size of your red blood cells

Anemia is usually what’s associated with abnormal MCH levels. If it’s determined that anemia is causing the abnormal MCH levels, the healthcare provider will then have to figure out what is causing the anemia. Depending on the cause and how severe the anemia is, you will receive a tailored treatment. Treatment for anemia might include:

MedicationSupplementsBlood transfusionBlood and bone marrow transplantSurgeryDietary changes

MCH stands for mean corpuscular hemoglobin. MCH measures the average amount of hemoglobin within a red blood cell. MCH is one measurement of your red blood cells’ health that is recorded during a complete blood count. The normal range for MCH is 27 to 31 picograms per cell.

Anything above or below that may indicate an underlying condition, usually a type of anemia. Low levels of MCH can indicate iron-deficiency anemia while high levels of MCH can signal anemia caused by low levels of folic acid or vitamin B12. A healthcare provider will determine what is causing your abnormal MCH levels.

If it’s anemia, they will determine what type of anemia it is and what is causing it. Then, they will be able to manage the cause and work to get your levels back to normal levels.

What medications cause high MCV?

Discussion – The causes of macrocytosis reported varies in different populations studied. Savage et al. in their study of 300 hospitalized patients in a New York City teaching hospital have reported drug therapy and alcohol abuse as the most frequent causes, and Vitamin B12/folate deficiency as uncommon (6%). Davidson et al. have also reported medications as the most frequent cause. Keenan et al. have observed that alcoholism followed by hematological disorders as the most frequent causes. However, their study has excluded drug induced causes. Mahmoud et al. have studied 124 patients in the age group of ≥75 years and found a higher incidence of hematological diseases and malignancy associated with macrocytosis. Breedveld et al. and Seppa et al. have reported Vitamin deficiency and alcoholism as the most frequent etiological factors, which is similar to the findings in the present study. Drugs reported to cause macrocytosis include reverse transcriptase inhibitors (Zidovudine, lamivudine, stavudine), anticonvulsants (valproic acid, phenytoin), folate antagonists (methotrexate), chemotherapeutics (alkylating agents, pyrimidine and purine inhibitors), sulfasalazine (anti inflammatory), pyrimethamine, trimethoprim, sulfamethoxazole, metformin and nitrous oxide. Most patients with HIV, being treated with reverse transcriptase inhibitors will display macrocytosis without anemia. In these patients, macrocytosis is considered a surrogate marker indicating the patients compliance in taking medications, Colon-Otero et al. have reported that 60% patients with macrocytosis present without anemia. In the present study, 83 cases (46.7%) presented without anemia and the remaining 95 cases (53.3%) had associated anemia. The relative incidence of anemia in our study varied among different etiologies, being most frequent in Vitamin B12/folate deficiency (Fig.1 ). Alcoholism was commonly associated with nonanemic macrocytosis. Another important observation in this study was that 9 cases (20.9%) of Vitamin B12 deficiency manifested isolated macrocytosis, without anemia. This re-emphasises the fact that macrocytosis can be an early diagnostic harbinger of Vitamin B12 deficiency, preceding anemia by months. It must be noted that MCV is an average value, and can be masked by a coexisting microcytic anemia like iron deficiency anemia, anemia of chronic illness and thalassemia trait, In the present study, the maximum MCV observed in Vitamin B12/folate deficiency was 146.8 fl, whereas in alcoholism it was 114 fl. In alcoholism, the MCV is usually reported to range between 100 and 110 fl, Ethanol appears to have a direct toxic effect on the marrow erythroid precursors. As the life-span of erythrocytes is 120 days, it may take 3–4 months for MCV to return to normal following abstinence from alcohol, The mean RDW (21.6%) in megaloblastic cases was significantly higher compared to nonmegaloblastic conditions (13.7%). Gupta et al. have compared the red cell parameters in macrocytosis of aplastic anemia and megaloblastic anemia and observed that RDW in megaloblastic anemia was significantly higher than the RDW in aplastic anemia. An increased RDW has been reported in megaloblastic anemia, myelodysplastic syndromes and chemotherapy, In liver disease and aplastic anemia, RDW is normal or mildly increased, Seppa et al. have compared the red cell parameters in macrocytosis of pernicious anemia and alcohol abuse. They found that a combination of low red cell count (<4 × 10 12 /l), high RDW (>15%), with a normal thrombocyte count and a normal thrombocyte mean cellular volume was highly sensitive in detecting Vitamin B12/folate deficiency. Bessmann et al. have developed an improved classification of anemias based on MCV and RDW. Megaloblastic processes are characterized by the presence of oval macrocytes (macro-ovalocytes) and hypersegmented neutrophils. However, hypersegmented neutrophils can sometimes be absent in megaloblastic conditions, if associated with marked left shift or severe neutropenia, Macro-ovalocytes are reported to be more sensitive but somewhat less specific than neutrophil hypersegmentation in predicting marrow megaloblastic changes, It is reported that an MCV >115 fl, increased RDW, macro-ovalocytes, and hypersegmented neutrophils suggest a megaloblastic disorder, Nonmegaloblastic conditions display uniformly round macrocytes and normal RDW, Round macrocytes are commonly seen in alcoholism and round, target-appearing macrocytes are characteristic of liver disease such as hepatitis and obstructive jaundice, In the present study, hypersegmented neutrophils and macro-ovalocytes were more frequently observed in megaloblastic macrocytosis. However, these features were also observed in a small percentage of alcoholism cases, who predominantly exhibited round, uniform macrocytes. Though not specific for one condition, an elevated MCV of >100 fl, is a useful parameter directing further investigations which can ultimately lead to a definitive diagnosis in 75% of cases, It may be the only indicator of vitamin deficiency and alcoholism, Mahmoud et al. believe that unexplained macrocytosis in the elderly (≥75 years) could be an early sign of Myelodysplastic syndrome. Joseph et al. have observed that refractory, unexplained macrocytosis may be an early sign of smoldering leukemia. Therefore regardless of the hemoglobin levels, close attention should be paid to MCV, Macrocytosis needs to be evaluated even in the absence of anemia, as it may be the first clue to an underlying pathology. Complete medical history including alcohol and drug intake, proper evaluation of red cell parameters and peripheral smear assist in arriving at a provisional diagnosis, thereby directing further management. This approach helps in determining the cause of macrocytosis, particularly in resource limited settings.

How do you fix a high MCV?

Vitamin B-12 deficiency
Folate deficiency
Liver disease
Alcoholism
Hypothyroidism
A side effect of certain medications, such as those used to treat cancer, seizures and autoimmune disorders
Increased red blood cell production by the bone marrow to correct anemia, for example, after blood loss
An underlying bone marrow cancer called myelodysplastic syndrome

How do you treat high MCV?

Blood tests – Your doctor will order blood tests to check for anemia and enlarged red blood cells. If your complete blood count indicates anemia, your doctor will do another test known as a peripheral blood smear, This test can help spot early macrocytic or microcytic changes to your red blood cells.

Additional blood tests can also help find the cause of your macrocytosis and anemia.
This is important because treatment depends on the underlying cause.
While nutrient deficiencies cause most macrocytic anemias, other underlying conditions may cause the deficiencies.
Your doctor will run tests to check your nutrient levels.

They may also do blood tests to check for alcohol use disorder, liver disease, and hypothyroidism, Your primary care doctor may also refer you to a hematologist. Hematologists specialize in blood disorders. They can diagnose the cause and specific type of your anemia.

Treatment for macrocytic anemia focuses on treating the cause of the condition.
The first line of treatment for many people is correcting nutrient deficiencies.
This can be done with supplements or foods like spinach and red meat.
You may be able to take supplements that include folate and other B vitamins.

You may also need vitamin B-12 injections if you don’t absorb oral vitamin B-12 properly. Foods high in vitamin B-12 include:

chickenfortified grains and cerealseggsred meatshellfishfish

Foods high in folate include:

dark leafy greens, such as kale and spinachlentilsenriched grainsoranges

Most cases of macrocytic anemia that are caused by vitamin B-12 and folate deficiencies can be treated and cured with diet and supplements. However, macrocytic anemias can cause long-term complications if left untreated. These complications can include permanent damage to your nervous system.

Extreme vitamin B-12 deficiencies may cause long-term neurologic complications. They include peripheral neuropathy and dementia, You can’t always prevent macrocytic anemia, particularly when it’s caused by underlying conditions out of your control. However, you can prevent the anemia from becoming severe in most cases.

Try these tips:

Does high MCV mean iron deficiency?

Frequently Asked Questions –

Can you have high MCV without anemia?

Conclusion – Macrocytosis is most commonly caused by alcoholism, Vitamin B12 deficiency and medications. Even in the absence of anemia, an increased MCV needs to be evaluated, as it may be the only clue to an underlying pathological condition. Complete history including medication and alcohol intake, proper evaluation of the red cell parameters and peripheral blood smear help in arriving at a provisional diagnosis in majority of cases.

Rosemarie Basco