What is the MCV Blood Test?

There are several different methods to assess recent or chronic alcohol consumption. At AlphaBiolabs, we can analyse hair, nail, breath and blood samples to determine drinking habits.

With so many different tests and packages to choose from, it can be hard to choose the right test for your particular needs.

In this article, we will take a look at the MCV blood test and what it is used for, the benefits of having an MCV blood test, and the accuracy of the test.

How do blood alcohol tests work?

There are several different types of blood alcohol tests available on the market. Each one looks for different markers that can give an indication of the amount of alcohol a person has consumed over varying periods of time.

A blood alcohol content (BAC) blood test looks for the amount of ethanol in your blood. Ethanol can be detected in the blood for around 12 hours, but this may vary depending on the amount you drink, your metabolism, and various other factors. An example of when a BAC blood test would be conducted is if you are caught drink-driving and cannot provide a specimen of breath to confirm your BAC.

Other blood alcohol tests look for the presence of direct and indirect biomarkers in the blood that are associated with excessive alcohol consumption. These blood tests include PEth, CDT, MCV and LFT.

PEth (phosphatidylethanol) is a direct marker of alcohol. It is only made by the body when alcohol has been consumed, and therefore is the most accurate blood alcohol test on the market. As it is a direct marker of alcohol, it can distinguish between chronic and occasional drinkers, and can also indicate if someone is abstinent from alcohol. It can provide an overview of alcohol consumption of up to four weeks.

CDT (carbohydrate-deficient transferrin) is a protein that is mainly produced by the liver. Whilst it is present in low amounts in people who drink occasionally or not at all, it is found in much higher levels in chronic drinkers, and so is a measure of chronic alcohol consumption. Although a CDT test can’t distinguish between non-drinkers and moderate drinkers, it is still extremely accurate at detecting chronic alcohol consumption, second only to PEth testing.

An MCV (mean corpuscular volume) test assesses the size of the red blood cells within a sample. If someone drinks excessively for a long period of time, they damage their bone marrow, which in turn causes the red blood cells to not form properly. This increases the MCV index and therefore indicates that someone is chronically abusing alcohol.

An LFT (liver function test) looks at three enzymes that are made in the liver. When someone abuses alcohol, their liver can become damaged. This damage affects the levels of these enzymes. An abnormal result indicates that the liver is damaged, which could be caused by chronic alcohol use.

What is an MCV test?

A mean corpuscular volume (MCV) test assesses the size of the red blood cells in a sample. The MCV index result indicates whether someone has been chronically drinking for a long period of time (over 6 weeks).

Alcohol affects our body’s ability to produce blood cells in different ways.

Alcohol use, particularly if excessive and/or chronic, can lead to nutritional deficiencies. Nutritional deficiencies can impact all parts of our body, including impairing the production and function of blood cells.

Alcohol also directly affects blood cell production because it has a toxic effect on the bone marrow. Our bone marrow makes all the different blood cells in our body through a complex process called haematopoiesis.

Chronic and excessive alcohol consumption also decreases the number of blood cell precursors. This results in structural abnormalities, such as enlarged red blood cells.

An MCV test measures the size of the red blood cells in femtolitres (fl). In a healthy adult, the normal MCV range is 80-100 fl. In people who drink chronically and excessively, the MCV index increases above this range.

Aside from alcohol consumption, an MCV test is often used in conjunction with other blood testing methods in the medical field to diagnose health problems that are not related to alcohol consumption, such as anaemia or hypothyroidism.

When is an MCV test used?

In the medical field, the MCV test is used to assess the size of your red blood cells, and to check for any signs of medical issues.

The MCV range in a healthy adult is about 80-100 fl. An MCV result below or above this range suggests that there is a medical issue causing microcytosis or macrocytosis respectively.

One medical condition that can be detected using an MCV test is anaemia. There are several types of anaemia with different causes. In general terms, anaemia is a condition where the body can’t make enough functioning red blood cells or haemoglobin. This causes symptoms such as lethargy, fatigue, muscle weakness and psychological issues.

Some types of anaemia cause your red blood cells to become smaller than normal (microcytic anaemia) and others, such as vitamin B deficiencies, cause them to become too big (macrocytic anaemia).

Abnormal MCV levels can also indicate other health problems, such as hypothyroidism and non-alcoholic fatty liver disease.

An MCV test may also be used to find out if someone is a chronic and excessive alcohol drinker. Since alcohol has both direct and indirect effects on your body’s ability to produce functioning red blood cells, it can cause your MCV levels to be higher.

Chronic and excessive alcohol consumption can lead to nutritional deficiencies, including deficiencies in vitamins B9 and B12. These vitamins are important in the production of healthy red blood cells. If there isn’t enough vitamin B9 or B12 in your body, it produces abnormally large red blood cells.

Excessive alcohol consumption also has direct toxic effects on the bone marrow, resulting in fewer blood cell precursors and the production of abnormally large red blood cells.

It takes about 6-8 weeks of excessive drinking (defined as 40g or more of alcohol consumption a day) for our MCV to become elevated. The MCV test therefore cannot distinguish between alcohol abstinence and occasional/moderate drinkers.

An MCV test is not usually used on its own to detect chronic and excessive alcohol consumption. This is because there are other factors that can cause your MCV level to become elevated. It is, however, a good indicator of chronic and excessive alcohol consumption when used in conjunction with other tests, such as PEth, CDT and LFT.

How accurate is the MCV test?

When we talk about the accuracy of a test, we are referring to the sensitivity and specificity of the test.

For example, a test that has 100% sensitivity for the detection of X means that of all the people tested that have X, 100% get a true positive result, and there are no false negatives.

A test that has 100% specificity for the detection of X means that of all people tested that do not have X, 100% get a true negative result, and there are no false positives (Cochrane UK, 2019).

The MCV test has a relatively low sensitivity. This is because there are several other factors that can increase the MCV. As the test is only looking at the size of the red blood cells, it cannot tell whether this increase in MCV is due to excessive alcohol consumption alone, or if there are other factors, like macrocytic anaemia, at play.

Pre-existing conditions may also skew the MCV index. Chronic drinkers may also have alcohol-induced microcytosis as well as macrocytosis. This causes something called dimorphic anaemia, which can lead to the average calculated MCV to fall into the normal range (Harris et al., 2021).

Furthermore, it can take several months for the MCV to return to normal levels after a chronic drinker stops drinking.

This may sound as though MCV has little value as a test for alcohol consumption.  However, when used in conjunction with other blood tests such as PEth, CDT and LFT, it can support a diagnosis of excessive drinking.

At AlphaBiolabs, we offer the MCV test as part of a blood alcohol testing package, as well as a blood and hair alcohol testing package, to ensure you only receive comprehensive, accurate and reliable results.

What are the benefits of the MCV test?

Although the MCV test is less sensitive than other blood alcohol tests, such as PEth or CDT, there are benefits of performing the MCV test in cases of suspected alcohol abuse.

If alcohol abuse is suspected or disclosed, an elevated MCV result supports the diagnosis of chronic excessive drinking.

The MCV test is a routine laboratory test that is performed here at AlphaBiolabs, but also in other places like hospital laboratories. There is lots of research and evidence available that supports the use of MCV as a marker of potential alcohol abuse, particularly when used alongside other blood alcohol tests.

As MCV stays elevated for several months even after a person stops drinking alcohol, a high MCV result can indicate if someone has abused alcohol in the past, even if they are not drinking anymore.

The results of the MCV test can help to confirm whether someone is abusing alcohol when used alongside the results from PEth, LFT and CDT tests.

How much does the MCV test cost?

The price of an MCV test depends on several factors.

The MCV test can be used to help identify health problems, as well as alcohol abuse.

Some companies offer MCV as a stand-alone test or as part of a package for people wanting to identify a potential health issue, or simply to check that their blood markers are okay. The price of these can range from about €50-€90, but it depends on the company and how many markers their panel looks at.

Whilst these tests can tell you if your MCV level is in the normal range, they can’t give you a diagnosis. They also can’t determine whether or not you are abusing or have abused alcohol in the recent past.

At AlphaBiolabs, we offer a blood alcohol testing package which includes MCV as a marker for alcohol abuse, alongside PEth, CDT and LFT. The combination of these tests gives you a clear picture on an individual’s drinking habits.

What is the normal MCV range?

The normal range for MCV is 80-100 fl in healthy adults. If you have a normal MCV result, it most likely means that the size of your red blood cells is normal. If the size of your red blood cells falls into the normal range, it suggests that you are less likely to be suffering from conditions that alter the size of your red blood cells, such as hypothyroidism, liver disease and alcohol abuse.

An MCV test result of less than 80 fl constitutes as low MCV. If your is less than 80 fl, it means that your red blood cells are smaller than they should be. The most common reason for this is microcytic anaemia (usually caused by an iron deficiency) but can also be caused by thalassemia (a genetic condition which lowers the amount of haemoglobin in your body) and some other reasons.

An MCV test result greater than 100 fl constitutes as high MCV. If your MCV is greater than 100 fl, it means your red blood cells are larger than they should be. There are several things that can cause your red blood cells to become too large, including chronic and excessive alcohol consumption vitamin B9 and B12 deficient anaemia, hypothyroidism and liver disease.

MCV versus other blood tests

How does the MCV test stack up against the other blood alcohol tests on the market? In this section, we summarise the key differences between the tests and talk about the advantages of doing these tests in combination.

MCV, PEth, LFT and CDT tests all require a blood sample. This is because the markers (direct or indirect) are found within the blood.

MCV vs PEth

PEth is the most accurate alcohol blood test available because it is a direct biomarker of alcohol consumption – it is only made by the body when you drink alcohol. MCV is less accurate because there are several things that can cause your red blood cells to become larger, not just alcohol consumption.

Whereas PEth can distinguish between abstinence, occasional and chronic drinking habits, MCV can only tell you if someone has chronically abused alcohol for a long period of time. In healthy adults, MCV will stay in the normal range if you are abstinent from alcohol, as well as if you are an occasional drinker, so it is not a good tool if you need to prove alcohol abstinence.

PEth is the only blood test that can be performed during pregnancy. MCV tests cannot be performed during pregnancy. This is because your MCV naturally increases when you are pregnant.

The PEth test can give an insight into someone’s drinking habits for up to four weeks. MCV can provide a longer overview in comparison. As it takes 6-8 weeks of chronic and excessive drinking for MCV to become elevated, and several months for MCV to return to normal after stopping alcohol consumption, MCV is a useful tool in assessing whether someone has abused alcohol in the recent past.

MCV vs CDT

Although not as accurate as PEth, CDT is a more accurate marker of alcohol consumption when compared to MCV.

When you drink excessively, you increase the amount of CDT in your blood. Both MCV and CDT are good indicators of chronic and excessive alcohol consumption, but neither can distinguish between abstinent and moderate drinkers.

If an excessive drinker stops using alcohol, their CDT levels should fall to normal levels within about 4 weeks. However, it takes several months for your MCV to return to normal after a period of excessive drinking, so MCV can be more helpful at identifying a past chronic drinker than CDT.

Significantly higher levels of CDT can be seen after heavy drinking for two weeks prior to taking the test. However, it takes MCV about 6-8 weeks to increase outside of the normal range.

Although both MCV and CDT are indicators of chronic alcohol abuse, the CDT test is more sensitive than MCV.

MCV vs LFT

Both LFT and MCV have functions outside of alcohol testing.

They are both routine tests that can be performed at hospital laboratories to identify potential health issues.

LFTs usually look for a number of different markers in the blood that can indicate problems in the liver. Depending on the levels of certain markers, the test results can help to identify the source of the problem (Lala et al., 2023).

Although the MCV test does not look for liver markers in the blood, elevated MCV can indicate potential problems with the liver. In a healthcare setting, MCV tests can be conducted alongside other tests, like the mean corpuscular haemoglobin (MCH), to identify problems such as anaemia.

Both LFT and MCV can provide useful information about someone’s drinking habits when used in conjunction with PEth and CDT. They have the lowest sensitivity of the four blood tests, because other health conditions and certain medications can cause abnormal MCV and LFT readings, but both the LFT and MCV tests can help to support a diagnosis of excessive drinking, when analysed alongside PEth and CDT.

Where can I get an MCV test?

As an accredited alcohol testing laboratory, we are well placed to support you with your alcohol testing needs, whether you are a member of the public who requires a legal alcohol test for official matters, a legal professional or social worker, or an employer looking to discourage alcohol abuse in the workplace.

Our laboratory is fully equipped to test a variety of samples for the presence of alcohol including blood, hair, and nails. We also offer point-of-care breath tests, as well as alcohol monitoring using SCRAM CAM®.

For more information, contact our friendly and discreet Customer Services team on 0140 29466 or email info@alphabiolabs.ie.