What is the reference range for globulin in serum?

• A. 2.3-3.5 g/dL
• B. 1.0-2.0 g/dL
• C. 3.0-4.0 g/dL
• D. 4.0-5.0 g/dL

Answer: (A)

Globulins are the set of non-albumin proteins in serum, including immunoglobulins and various carrier and transport proteins. In adults, the amount of globulins is typically about 2.3 to 3.5 g/dL. This range reflects how much of the total serum protein is made up by these proteins and is commonly used as the reference interval in clinical laboratories.

Total protein is usually around 6–8 g/dL and albumin about 3.5–5 g/dL; globulins make up the remainder, falling near that 2.3–3.5 g/dL window. Lab methods and populations can shift the exact numbers slightly, but 2.3–3.5 g/dL is the standard benchmark.

The other ranges are outside the usual globulin window, so they don’t fit as well with how globulins are quantified in routine chemistry.