What Does a High or Low A/G Ratio Mean? (2024)

The A/G ratio is a test that measures the amount of proteins called albumin and globulin in your blood. The A/G ratio may be performed as part of a routine blood test called the comprehensive metabolic panel (CMP) or ordered if you have certain unusual symptoms like hematuria (blood in the urine) or jaundice (yellowing of the eyes or skin).

A high A/G ratio may indicate kidney disease, an antibody deficiency, or severe dehydration. A low A/G ratio can also indicate kidney disease, liver disease, chronic infections like HIV, autoimmune diseases like lupus, and certain cancers.

This article explains why the A/G ratio test is used and what the ratio of albumin to globulin says about your health. It also describes what you need to do if your test results are high or low.

Albumin/Globulin Ratio Results: What's Measured

The A/G ratio describes the amount of albumin compared to the amount of globulin in your blood. Albumin and globulin are major proteins in your blood, called serum proteins. They have different purposes in the human body, as follows:

• Albumin, produced by the liver, helps fluids remain inside blood vessels and prevents them from leaking into your lungs, abdomen, or other parts of your body. A normal albumin range isbetween 3.4 and 5.4 grams per deciliter (g/dL).
• Globulins produced by the liver (called alpha and beta globulins) and the immune system (called immunoglobulins or antibodies) play a role in liver function, blood clotting, and fighting infections. A normal globulin range is between 2.0 and 3.5 g/dL.

Under normal circ*mstances, there is slightly more albumin in your blood than globulin.

Although the reference ranges of values—meaning the range between which test results are normal—can differ by the lab, an A/G ratio between 1.1 and 2.5 is generally considered normal.

What Does a Low A/G Ratio Mean?

When your body is functioning normally, the proportion of albumin to globulin will remain relatively consistent. When the proportion changes and the A/G ratio is low, it may be a sign of an infection, disease, or nutritional deficiency.

Your A/G ratio may become low for three reasons:

• Your albumin is normal, but your globulin is high.
• Your albumin is low, and your globulin is high.
• Your globulin is normal, but your albumin is low.

Low albumin (hypoalbuminemia) is most often due to the reduced production of albumin by the liver or the excessive loss of albumin in urine (due to a kidney problem). Chronic inflammatory diseases can also make blood vessels more permeable, leading to albumin loss.

In contrast, high globulin levels are typically a sign of inflammation or the activation of the immune system to fight an infection or disease.

To this end, the possible causes of a low A/G ratio include:

• Chronic kidney disease
• Liver disease (including cirrhosis)
  
• Pancreatitis (inflammation of the pancreas)
• Chronic infections (such as HIV,tuberculosis, andhepatitis)
• Malnutrition (which decreases the amino acids needed to make albumin)
  
• Autoimmune diseases (such as lupus and rheumatoid arthritis that cause chronic, multi-organ inflammation)
• Gastrointestinal diseases (like celiac disease, ulcerative colitis, and Crohn's disease that cause protein loss)
• Gastrointestinal (GI) cancers (like stomach cancer, colon cancer, and pancreatic cancer)
• Multiple myeloma (a type of blood cancer that blocks the production of albumin and increases globulin levels)
• Type 2 diabetes(in which low insulin decreases albumin production while persistently high blood sugar causes kidney damage)
• Nephrotic syndrome (a complication of kidney diseases that causes too much protein to be excreted from the body in urine)

A low A/G ratio does not cause symptoms other than those related to the underlying cause.

Your healthcare provider will often order an A/G ratio test if you have signs of chronic kidney disease (including difficulty urinating, ankle swelling, and ammonia-smelling breath) or liver disease (including jaundice, dark urine, severe fatigue, and pain in the upper right abdomen).

What Does a High A/G Ratio Mean?

A high A/G ratio is far less common than a low A/G ratio and may occur when:

• Your albumin is high, and your globulin is normal.
• Your globulin is low, and your albumin is normal.
• Your albumin and globulin are both high, but the proportion is abnormal.

Globulin levels can drop when your body does not produce enough or an excessive amount is eliminated through the kidneys when you urinate. In contrast, the only situation in which albumin can abnormally increase is with severe dehydration.

To this end, possible causes of a high A/G ratio include:

• Severe diarrhea or vomiting (or other causes of severe dehydration)
• Pregnancy (during which albumin and globulin will increase to support fetal growth)
• Antibody deficiency disorders (a group of genetic disorders that cause the inadequate production of immunoglobulins)

A high A/G ratio does not cause a set group of symptoms. In many cases, there may be no symptoms.

However, people with low immunoglobulins are vulnerable to recurrent pneumonia, bronchitis, sinus infections, ear infections, meningitis, or skin infections.

Diagnosing the Cause of Low or High A/G Ratio

An A/G ratio cannot diagnose any medical condition on its own, but it can point your healthcare provider in the direction of possible causes. Other tests can help characterize the nature of the problem and help narrow the causes.

These involve lab tests like:

• Complete blood count (CBC): A standard panel of blood tests that can detect signs of inflammation or infection
• Urinalysis: A urine-based test that can detect excess protein in urine (proteinuria)
• Creatinine clearance (CrCl): A blood test that can detect a waste product called creatinine that can accumulate in the blood when the kidneys are damaged
• Estimated glomerular filtration rate (eGFR): A test that calculates how well or how poorly the filtering unit of the kidneys, called glomeruli, are working
• C-reactive protein (CRP): A blood test that can detect generalized inflammation in the body
• Erythrocyte sedimentation rate (ESR): A blood test that measures general inflammation based on how quickly red blood cells settle to the bottom of a test column
• Liver function tests (LFTs): A battery of tests used to check for signs of liver disease
• Antinuclear antibody (ANA): A blood test that can check for abnormal antibodies seen with different types of autoimmune diseases

Imaging tests and specialist procedures may be also used if a gastrointestinal disease or cancer is suspected, such as:

• Imaging studies: Including X-ray, ultrasound, computed tomography (CT), or magnetic resonance imaging (MRI)
• Endoscopy: A minimally invasive test in which a fiberoptic scope is inserted into the mouth or rectum to view the digestive tract
• Biopsy: A procedure used to obtain a sample of tissue samples for evaluation in the lab to check for cancer, inflammatory diseases, or certain autoimmune disorders
  

Summary

An A/G ratio is a blood test that compares the amount of two proteins (albumin and globulin) in your blood. A normal A/G ratio is between 1.1 and 2.5, although this can vary by lab.

A low A/G ratio may be due to kidney disease, liver disease, chronic infections, type 2 diabetes, malnutrition, certain autoimmune diseases, and cancers. A high A/G ratio may also be due to kidney disease as well as severe dehydration, pregnancy, and antibody deficiencies.