A serum albumin and globulin (A/G) ratio test is a type of blood test. It measures the ratio of albumin to globulin, the two main proteins in your blood.

Typically, an A/G ratio test is done as part of a routine protein blood test. It’s used to check your general health, including nutritional status and immune function.

This blood test is also used to screen and monitor various health conditions, including kidney disease, chronic infections, various cancers, and more.

In this article, we’ll explain the purposes of an A/G ratio blood test, what the process of getting tested is like, and how results are interpreted.

Serum is the clear fluid part of blood that contains no blood cells and clotting components. This serum contains proteins, which are known as serum protein.

Serum protein consists of two main proteins:

  • Albumin proteins. Albumin, which makes up 50 percent of serum protein, reflects your nutritional status. Albumin proteins transport substances like hormones, fatty acids, and drugs throughout your body.
  • Globulin proteins. Globulin proteins, which are made by your immune system, make up around 48 percent of serum protein. These proteins indicate the state of your immune function and the severity of any inflammation.

The purpose of an A/G ratio test is to measure the ratio of albumins to globulins.

Since its results give insight into your nutritional status and immune function, this blood test is also useful for diagnosing and monitoring many health conditions.

The normal range for albumin/globulin ratio is over 1, usually around 1 to 2. That’s because there’s a bit more albumin than globulin in serum protein.

If your body is producing too much or too little of either protein, your A/G ratio will be classified as high or low.

A low A/G ratio could indicate your albumin levels are too low (hypoalbuminemia), or your globulin levels are too high. High globulin indicates inflammation and immune system activity.

Overall, a low A/G ratio result is associated with:

A 2010 research overview found low albumin levels were partially predictive of increased mortality rates for those with gastrointestinal, lung, and breast cancers among others.

High albumin concentration can be caused either by overproduction of albumin by the liver, or when fluid (serum) levels are too low.

When a high A/G ratio is caused by high albumin levels, this can be due to severe dehydration or diarrhea, but can also occur during pregnancy. As the National Institutes of Health (NIH) explains, healthy kidneys don’t allow albumin to pass from blood into urine. High albumin in urine (albuminuria) can be an indicator of kidney disease.

A high A/G result might also indicate low levels of globulin, which are found in people with antibody deficiencies, meaning a weakened immune system.

Low globulin levels can also occur due to malnutrition. Malnutrition can be caused by inflammatory bowel or other gastrointestinal diseases, eating disorders, and not eating a balanced diet.

The A/G ratio blood test is sometimes, but not always, done as part of a comprehensive metabolic panel (CMP). A CMP is typically done at routine health checkups.

When done as part of a CMP, you’ll likely need to fast before the test, meaning you can’t eat or drink for a certain period of time leading up to your blood draw. This doesn’t have anything to do with the A/G ratio component specifically but is relevant for other parts of the CMP. If you are just having an A/G test you will not have to fast.

The procedure is a simple blood test, which can take place in a doctor’s office. It usually involves the following steps:

  1. A phlebotomy technician (expert in blood drawing) will locate a vein in your arm.
  2. They will clean the area of skin with an antiseptic wipe.
  3. The technician will insert a thin needle into the vein, drawing blood out from the needle into a plastic hose that fills a test tube. The tube is marked with your patient information.
  4. If multiple samples are needed, the technician will replace the test tubes multiple times as they fill up.
  5. After the samples are collected, the technician will remove the needle and apply pressure to the site. You’ll receive a small bandage.

You may have an elastic band tied around your arm above the vein, or be asked to squeeze a stress ball, to increase blood flow. Once the blood draw process begins, it usually only takes several seconds to complete.

There is also a protein urine test. Depending on the reasons for checking your A/G ratio, and your results, your doctor might also order this test.

Your doctor might order an A/G ratio test if you have certain symptoms that are cause for concern. This is particularly likely if your symptoms suggest kidney or liver problems.

These include:

The A/G ratio test often is used to assess the severity of disease progression, and even predict mortality rates. You may receive this blood test if you are being treated for an illness in the hospital, or if you live with a chronic condition like liver or kidney disease.

In some cases, you might not need a specific reason to get your A/G ratio checked. Depending on your doctor and lab, your A/G ratio might be measured during your routine CMP.

Treatment after A/G ratio test results

There is no single treatment for a high or low A/G result, as this will vary depending on the underlying health condition. Treatment will also depend on any other exams or tests your doctor performs regarding your symptoms.

An A/G ratio test measures albumin and globulin, the two main proteins in your blood. This simple blood test is used to monitor your nutritional status, immune function, and overall health.

High or low A/G ratios are particularly associated with kidney and liver disease. A low A/G ratio can also indicate chronic infections, cancers, and more. A high A/G ratio is associated with dehydration, malnutrition, and other gastrointestinal conditions.

Your doctor might check your A/G ratio if you’re experiencing unexplained weight loss, extreme fatigue, or swelling. Additionally, if you’ve been diagnosed with a chronic condition, they might use the test to monitor your progress.