A/G Ratio Biomarker | Walk-In Lab

Overview

The A/G (albumin to globulin) ratio is a blood‑based biomarker that compares the amount of albumin to the amount of globulin proteins in your bloodstream. Albumin is mainly made by the liver and helps keep fluid in blood vessels, transport hormones and drugs, and support nutrition and blood pressure. Globulins are a group of proteins that include antibodies and other molecules involved in immune defense and inflammation.

A low A/G ratio usually means albumin is decreased, globulins are increased, or both, which can occur in liver disease, chronic inflammation, kidney disease, malnutrition, or certain cancers and immune disorders. A high A/G ratio often reflects relatively low globulins (for example, in some immune‑deficiency states) or, less commonly, conditions that raise albumin relative to globulins, such as dehydration. The ratio is useful because it gives a quick snapshot of overall protein balance and can help flag liver, kidney, nutritional, or immune problems when interpreted with other lab tests and clinical findings.

Clinical Use Cases

Routine health screening when included in a comprehensive metabolic panel.
Evaluating or monitoring liver disease, such as cirrhosis or chronic hepatitis.
Assessing kidney disease, particularly conditions causing protein loss in urine (for example, nephrotic syndrome).
Checking nutritional status and chronic malnutrition.
Detecting or monitoring chronic inflammation, autoimmune diseases, and certain cancers (for example, multiple myeloma).
Supporting prognosis and risk assessment in some cancers and cardiovascular conditions, where a lower A/G ratio has been linked with worse outcomes in adult populations.

Specimen Types

Serum (most common)
Plasma

Measurement Methods

Quantitative measurement of total protein and albumin by spectrophotometric or colorimetric methods.
Calculation of globulin as the difference between total protein and albumin (globulin = total protein - albumin).
Direct A/G ratio calculated as albumin divided by globulin, often reported alongside the individual protein values.

Test Preparation and Influencing Factors

Fasting is usually not required for a standalone A/G ratio test, but may be needed if the test is ordered as part of a comprehensive metabolic panel; in that case, an 8–12 hour fast (water only) is common.
Severe dehydration can increase albumin and total protein, which may raise the A/G ratio.
Chronic inflammation, infections, autoimmunity, and some cancers can increase globulins, lowering the ratio.
Malnutrition, liver disease, and kidney disease with protein loss can reduce albumin and lower the A/G ratio.
Certain medications (for example, large‑dose corticosteroids, some chemotherapy drugs, or drugs that affect liver or kidney function) may alter protein levels and therefore the ratio.
Pregnancy and older age can shift baseline albumin levels, slightly affecting the ratio even in otherwise healthy people.