Total Protein Above or Below the Normal Range: Causes in Athletes and What to Do
Total protein is a routine line on many blood test reports, often appearing alongside liver function tests. Athletes frequently notice a value flagged just above or below the range and wonder whether it reflects their diet, their protein shakes or their training. The answer is usually more mundane — hydration plays a big role — but occasionally an abnormal result is the first clue to liver, kidney, immune or nutritional problems. Our editorial team explains what the number means.
What total protein measures
Serum total protein is the combined concentration of all proteins in the liquid part of the blood. Two groups make up almost all of it: albumin, produced by the liver, and globulins, a diverse family that includes antibodies (immunoglobulins), transport proteins and clotting-related proteins.
In UK laboratories, total protein is reported in grams per litre (g/L). A typical adult reference range is roughly 60–80 g/L, with albumin around 35–50 g/L. Exact limits vary between laboratories, so the range printed on the report should always be used.
The ratio between albumin and globulin is often more informative than the total. Many reports calculate globulin as total protein minus albumin, which helps distinguish between different causes of an abnormal result.
Importantly, serum total protein does not measure how much protein you eat or how much muscle you carry. It reflects production, loss and dilution of blood proteins.
Common reasons for a high result
The most common cause of a mildly raised total protein in athletes is haemoconcentration — blood that is more concentrated than usual. This happens with dehydration, after a sweaty session or a long fast, and even with a tight tourniquet left on too long during blood sampling.
Other causes include:
- chronic inflammation or infection, which raises globulins;
- chronic liver conditions, in which globulins may rise while albumin falls;
- autoimmune diseases such as rheumatoid arthritis or lupus;
- paraproteinaemias, including monoclonal gammopathy and myeloma, where one abnormal immunoglobulin is overproduced.
A high-protein diet or protein supplements do not meaningfully raise serum total protein in healthy people. The body tightly regulates plasma protein levels, and excess dietary protein is used for energy or excreted as urea.
A persistently high globulin fraction, especially in someone over 50 or with bone pain, fatigue or anaemia, warrants further tests such as serum protein electrophoresis, which a GP can arrange.
Common reasons for a low result
Low total protein usually reflects low albumin. Overhydration — drinking large amounts of fluid before a test — can dilute the blood slightly, and pregnancy causes a physiological drop.
Clinically important causes include liver disease (reduced production), kidney disease with protein loss in the urine (nephrotic syndrome), gut conditions that impair absorption or cause protein loss, such as coeliac disease or inflammatory bowel disease, and severe acute illness.
In athletes, prolonged low energy availability deserves particular attention. Severe or long-standing under-fuelling, as seen in Relative Energy Deficiency in Sport (REDs) and eating disorders, can eventually lower albumin and total protein, although these markers often stay normal until malnutrition is advanced. A normal total protein does not rule out under-fuelling.
Anabolic steroids and other liver-stressing substances can impair liver function, which in more serious cases may lower albumin. Users should disclose them to their doctor so results are interpreted accurately.
How doctors investigate an abnormal result
A slightly abnormal total protein with otherwise normal tests and no symptoms is usually repeated under standard conditions before any further work-up. Many borderline results simply normalise.
| Finding | Likely next step |
|---|---|
| Mildly high total protein, normal albumin/globulin balance | Repeat when well hydrated and rested |
| High globulin | CRP, immunoglobulins, serum protein electrophoresis |
| Low albumin | Liver tests, urine protein (ACR/PCR), kidney function |
| Low albumin with GI symptoms | Coeliac serology, faecal calprotectin, specialist referral |
| Low albumin with weight loss | Dietary and energy availability assessment |
The doctor will also consider symptoms such as swelling of the legs or around the eyes, frothy urine, jaundice, chronic diarrhoea, recurrent infections or unexplained weight loss.
Because total protein is non-specific, it is never interpreted in isolation. It is one piece of a larger puzzle that includes history, examination and other blood and urine tests.
Preparing for a blood test and practical steps
To avoid misleading results, arrive for the test normally hydrated — neither after an extreme fast without fluids nor after downing a litre of water. Avoid very hard training in the 24–48 hours beforehand if possible, and note any recent illness.
If your result is low and you suspect under-eating, the solution is not a protein shake alone. Adequate total energy intake, balanced meals and, where appropriate, support from a sports dietitian and doctor address the root cause. Athletes typically need 1.2–2.0 g of protein per kilogram of body mass per day, but this matters for muscle and recovery rather than for the blood test figure.
If your result is high, review hydration first and request a repeat test. Persistent elevation, especially with symptoms, should be followed up rather than ignored.
Keep copies of your results to track trends over time. A value that drifts steadily in one direction is more meaningful than a single borderline flag.
Editorial team's conclusions
Serum total protein is a broad marker influenced strongly by hydration, liver and kidney function, inflammation and severe nutritional deficits. It does not reflect protein intake or muscle mass. In athletes, mild deviations are usually due to fluid status or recent training, but persistent or marked abnormalities — particularly with symptoms — deserve investigation by a doctor.
You may also want to read our guides to C-reactive protein in athletes, interpreting liver enzymes (ALT and AST) after training, and recognising Relative Energy Deficiency in Sport.
References
- Busher JT. Serum albumin and globulin. In: Walker HK, Hall WD, Hurst JW, editors. Clinical Methods: The History, Physical, and Laboratory Examinations. 3rd ed. Boston: Butterworths; 1990. Chapter 101.
- Mountjoy M, Ackerman KE, Bailey DM, et al. 2023 International Olympic Committee's (IOC) consensus statement on Relative Energy Deficiency in Sport (REDs). Br J Sports Med. 2023;57(17):1073–1097.
- Lee EC, Fragala MS, Kavouras SA, et al. Biomarkers in sports and exercise: tracking health, performance, and recovery in athletes. J Strength Cond Res. 2017;31(10):2920–2937.
- Jäger R, Kerksick CM, Campbell BI, et al. International Society of Sports Nutrition position stand: protein and exercise. J Int Soc Sports Nutr. 2017;14:20.
- Kyle RA, Therneau TM, Rajkumar SV, et al. Prevalence of monoclonal gammopathy of undetermined significance. N Engl J Med. 2006;354(13):1362–1369.
