Albumin Globulin Ratio Calculator (A/G ratio and globulin from total protein)

Understanding the albumin globulin ratio calculator — concept and principle

This calculator works out serum globulin and the albumin-to-globulin (A/G) ratio from total protein and albumin on a blood test. It also shows albumin's share of total protein, whether albumin or globulin predominates and whether total protein is within 6.0–8.3 g/dL. Patients reading a liver or protein panel and students use it.

How it is calculated

• Globulin = total protein − albumin
• A/G ratio = albumin ÷ globulin
• Albumin share = albumin ÷ total protein × 100
• 1 g/dL = 10 g/L

Total protein 6.0–8.3 g/dL is a commonly cited reference range; each laboratory sets its own.

The principle

Blood proteins are mainly albumin, made by the liver, and globulins, which include antibodies and carrier proteins. Laboratories usually measure total protein and albumin; globulin is the difference. Normally there is somewhat more albumin than globulin, so the ratio is usually a little above 1. A low ratio can result from low albumin, for example in liver or kidney disease or malnutrition, or from high globulins in chronic inflammation, autoimmune disease or some blood cancers. A high ratio can come from low globulin levels.

Worked example

Defaults: total protein 7.2 g/dL; albumin 4.3 g/dL.

1. Globulin = 7.2 − 4.3 = 2.9 g/dL = 29 g/L.
2. A/G ratio = 4.3 ÷ 2.9 = 1.48.
3. Albumin share = 4.3 ÷ 7.2 = 59.7%: More albumin than globulin.
4. Total protein within 6.0–8.3 g/dL? Yes.

How to read the result

The ratio is a clue, not an answer. An unusual value usually leads to further tests such as serum protein electrophoresis. Compare with the reference range printed on your report, since methods differ between laboratories.

Common mistakes

• Mixing g/dL and g/L.
• Using total protein and albumin from different dates.
• Reading the ratio without looking at the albumin and globulin values themselves.
• Applying one laboratory's range to another's results.

Frequently asked questions

What is a normal A/G ratio?

Usually a little above 1, but use your laboratory's reference range.

What does a low A/G ratio mean?

Either albumin is low or globulins are high; further tests are needed to find out which and why.

How is globulin calculated?

Total protein minus albumin.

Sources: MedlinePlus (US National Library of Medicine), "Total Protein and Albumin/Globulin (A/G) Ratio" · MedlinePlus Medical Encyclopedia, "Total protein" (article 003483)