30 Protein, Total

Total protein: albumin and globulins, causes of low and high values, when protein electrophoresis is needed.

Total protein is the sum of all proteins in the serum, mainly albumin (about 60 %) and globulins (about 40 %). These proteins keep water inside blood vessels (oncotic pressure), transport hormones, drugs, minerals and fats, form antibodies and take part in clotting and inflammation. Total protein is a broad screening test. Its components, albumin, globulins and their ratio, usually tell more than the total itself.

Blood proteinsNutritionLiver and kidney

Adults60–80 g/L (6–8 g/dL)

Albumin35–50 g/L

Globulinstotal − albumin ≈ 20–35 g/L

Albumin/globulin ratio≈ 1.1–2.0

Figure 1. Total protein zones. Abnormal values are interpreted together with albumin, globulins and, if needed, serum protein electrophoresis.

Low total protein

Too little production: liver cirrhosis, malnutrition, malabsorption (coeliac disease, inflammatory bowel disease)
Losses: nephrotic syndrome (protein in urine), protein-losing enteropathy, severe burns, bleeding
Dilution: intravenous fluids, pregnancy, heart failure with fluid retention

Low protein, especially low albumin, causes swelling (oedema) of the legs and abdomen and slows wound healing.

High total protein

Dehydration — all proteins are concentrated (albumin also high)
Increased globulins — chronic infections (HIV, hepatitis B and C, tuberculosis), autoimmune diseases, chronic liver disease
Paraproteins — multiple myeloma, Waldenström macroglobulinaemia, monoclonal gammopathy of undetermined significance (MGUS)

What to do

An abnormal total protein should be broken down into albumin and globulins. An unexplained high total protein or globulin fraction, especially with anaemia, bone pain, kidney problems or high calcium, needs serum protein electrophoresis to look for a paraprotein.

References

Busher JT. Serum albumin and globulin. In: Walker HK, Hall WD, Hurst JW, eds. Clinical Methods: The History, Physical, and Laboratory Examinations. 3rd ed. Boston: Butterworths; 1990. Chapter 101. ncbi.nlm.nih.gov/books/NBK204
Kwo PY, Cohen SM, Lim JK. ACG clinical guideline: evaluation of abnormal liver chemistries. Am J Gastroenterol. 2017;112(1):18–35. doi:10.1038/ajg.2016.517

This article is for general information and does not replace a consultation with a doctor. Laboratory results must be interpreted by a physician together with symptoms and other tests.

Published on 30 April 2024