What does it measure?
Laboratories usually calculate globulin by subtracting albumin from total protein, then divide albumin by globulin. No new protein is measured by the ratio itself. The calculation can make a change in protein balance easier to notice, even when total protein looks ordinary. [1]
Before reading the calculation
- Inputs
- Albumin divided by globulin. Globulin is often calculated by subtracting albumin from total protein.
- Reading the calculation
- Keep albumin and total protein alongside the ratio; each helps explain which part changed.
What can the result mean?
A low ratio may reflect lower albumin, higher globulins, or both. These changes can have different causes, including inflammation, liver disease, or protein loss. A high ratio can reflect lower globulins. Neither direction identifies one diagnosis without the underlying results. [1]
Albumin divided by globulin. Globulin is often calculated by subtracting albumin from total protein.
- Reading the calculation
- Keep albumin and total protein alongside the ratio; each helps explain which part changed.
When is it useful, and how is it read?
A low ratio could reflect reduced albumin, increased globulins, or both. Those paths suggest different questions, such as protein loss, inflammation, or liver disease. Persistent unexplained changes may call for an assessment of protein fractions, guided by the symptoms and the actual component results. [1] [3]
What can affect it?
Hydration, illness, laboratory methods, and medicines can affect the components. Because globulin is often calculated, measurement variation in albumin or total protein also affects the ratio. A number close to a laboratory boundary should be interpreted with the full pattern and previous results. [1]
Globulin is often calculated from two measured values
On many routine panels, globulin is estimated as total protein minus albumin, then used in the A/G ratio. The ratio therefore summarizes its components; it does not independently identify which globulin proteins are present. [2]
Questions you might have
Can a low ratio have more than one explanation?
Yes. Low albumin, high globulins, or both can lower it. The original values are needed to distinguish these patterns. [1]
Does the ratio identify which globulin changed?
No. It combines the globulin portion into one number and does not separate individual proteins. [1]
What comes next?
Start by reviewing which component changed. Your clinician may check urine protein, liver findings, or individual protein groups if there is a persistent unexplained abnormality. Do not treat the ratio with extra dietary protein unless an actual nutritional issue has been established. [1]
Which part of the ratio is changing, and would checking specific proteins help?
The reference interval and units on your report are part of understanding your result. Understand units, reference intervals, and treatment targets.
Sources & references
Medical references & original research
Books we consulted
References that informed our explanations of the test and its context.
- Pagana KD, Pagana TJ, Pagana TN. Mosby’s Diagnostic and Laboratory Test Reference. 14th ed. Elsevier; 2019.
Practical-section sources accessed: .
For general health education. Interpreting your result and deciding on tests or treatment requires your health context and a qualified clinician.
