Uric acid above or below normal: causes in athletes and what to do

Elevated uric acid in a test is a frequent finding in strength-sport athletes and people with a large body mass, while a reduced level occurs less often but also has its explanation. The editorial team examines which causes of deviations are most typical for those who train, when it is worth worrying and which steps help return the indicator to a safe range.

Temporary increase after exertion

The most common cause of "unexpectedly high" uric acid in an active person is training the day before the test. During intense work part of the ATP breaks down to hypoxanthine, which is then converted to uric acid. The effect is especially pronounced after sprints, interval sessions, CrossFit workouts and long competitions.

The blood level usually rises over several hours after exertion and can remain higher than baseline the next day. In parallel, lactate formed during work competes with urates for excretion in the renal tubules and for a time inhibits their excretion.

The effect is enhanced by dehydration. A reduction in plasma volume and renal blood flow raises the concentration of all substances excreted by the kidneys. An athlete who, after training in the heat, has not sufficiently restored fluid may get a result that differs noticeably from their usual values.

Therefore, before drawing conclusions, it is worth repeating the test under standard conditions: in the morning on an empty stomach, after normal drinking, without heavy training for at least a day or two. If the repeat result is normal, the first increase was most likely situational.

Persistent increase: nutrition, body mass, medications

If uric acid is persistently elevated, the causes are usually chronic in nature. The first is a diet with a large amount of red meat, offal, seafood, as well as alcohol (especially beer) and sugary fructose-containing drinks. Cohort studies by Choi and co-authors link precisely these products with a higher risk of gout, whereas dairy products had a protective association.

The second cause is a large body mass and insulin resistance. Insulin enhances the reabsorption of urates in the kidneys, so people with abdominal obesity and metabolic syndrome have higher levels. For athletes in heavy weight categories who deliberately maintain a high mass, this is especially relevant.

The third is medications and substances. Thiazide and loop diuretics, low doses of aspirin, cyclosporine, some anti-tuberculosis drugs raise uric acid levels. Diuretics, which athletes sometimes use for weight "cutting" or "dryness" (and which are on the WADA Prohibited List), add dehydration to this effect.

Finally, a high level can be a sign of chronic kidney disease, hypothyroidism, blood diseases with increased cell breakdown, or hereditary features of urate excretion. In some people hyperuricemia has a pronounced genetic component (Dalbeth et al., 2016).

• An excess of meat, seafood, alcohol, fructose.
• High body mass, insulin resistance.
• Diuretics, low doses of aspirin, other medications.
• Sharp fasts and ketogenic diets at the start.
• Diseases of the kidneys, thyroid, blood; heredity.

Consequences of hyperuricemia

The best-known consequence is gout. When the urate concentration exceeds the solubility threshold (about 6.8 mg/dL), sodium urate crystals can form in the joints. A typical attack is sudden severe pain, redness and swelling of a joint, most often the metatarsophalangeal joint of the big toe. Triggers of an attack are dehydration, alcohol, abundant food and joint injury.

The second problem is kidney stones. Urate stones form more often with acidic urine and a low volume of urination, that is, precisely in situations of chronic under-drinking typical of some athletes.

Hyperuricemia is also linked to arterial hypertension, chronic kidney disease and cardiovascular diseases. The causal nature of these links is still being discussed, but in any case a persistently high indicator is a signal to assess overall metabolic health.

At the same time it is important not to exaggerate: most people with asymptomatic hyperuricemia will never have gout, and the ACR guidelines (2020) do not recommend prescribing such people uric-acid-lowering drugs merely because of a figure in a test.

Low uric acid

A reduced uric acid level (hypouricemia) occurs much less often. It is most frequently linked to taking medications: allopurinol or febuxostat, losartan, fenofibrate, high doses of vitamin C. The level also decreases in pregnancy and in some conditions with increased renal excretion.

The cause may be very low intake of purines and protein — for example, with prolonged strict dietary restriction. If other indicators of nutritional status are reduced in parallel, it is worth assessing the energy balance in the context of RED-S syndrome.

For athletes there is a specific rare scenario — hereditary renal hypouricemia, in which the kidneys excrete urates excessively. It is described mainly in people from East Asia and is associated with the risk of acute kidney injury after intense anaerobic exertion, for example sprint running. If a very low level is found without an obvious cause, it is worth discussing this with a nephrologist.

In other cases low uric acid rarely has clinical significance in itself, but since it is a plasma antioxidant, some researchers are studying its link with neurodegenerative diseases. For an athlete's practice this so far has no direct consequences.

What to do with a deviation

With a one-time increase without symptoms, the first step is a repeat test under standard conditions. If the increase is confirmed, a doctor usually assesses creatinine, lipids, glucose, blood pressure and, if necessary, a urine test, to understand the metabolic context.

Non-drug measures recommended by rheumatology guidelines (EULAR 2016, ACR 2020) are limiting alcohol, sugary fructose drinks, an excess of meat and seafood, normalizing body mass, and adequate water intake. For an athlete it is important that dairy products and milk proteins can be kept in the diet.

During periods of weight "cutting" and in hot weather, the risk of a gout attack in susceptible people rises, so hydration should be planned especially carefully. Sharp fasts are also better replaced by a gradual calorie deficit.

If acute pain and swelling of a joint appear, a doctor's consultation is needed: to "tough out" an attack on your own and continue training on the affected joint is a bad idea. The decision on drug lowering of uric acid is made by a rheumatologist, taking into account the frequency of attacks, the presence of tophi and the condition of the kidneys.

Editorial conclusions

Elevated uric acid in athletes is often a consequence of training or dehydration the day before the test, so one should start by checking the collection conditions.

Persistent hyperuricemia is linked to nutrition, body mass, medications and heredity and raises the risk of gout and kidney stones, although it does not always require medication in itself.

Low uric acid is most often explained by medications, and rare renal hypouricemia requires caution with intense anaerobic exertion.

We also recommend reading our materials on what the uric acid test shows, on potassium and sodium in athletes and on creatinine and kidney function.

References

1. FitzGerald JD, Dalbeth N, Mikuls T, et al. 2020 American College of Rheumatology Guideline for the Management of Gout. Arthritis Care Res (Hoboken). 2020;72(6):744–760.
2. Richette P, Doherty M, Pascual E, et al. 2016 updated EULAR evidence-based recommendations for the management of gout. Ann Rheum Dis. 2017;76(1):29–42.
3. Dalbeth N, Merriman TR, Stamp LK. Gout. Lancet. 2016;388(10055):2039–2052.
4. Choi HK, Atkinson K, Karlson EW, Willett W, Curhan G. Purine-rich foods, dairy and protein intake, and the risk of gout in men. N Engl J Med. 2004;350(11):1093–1103.
5. Choi HK, Curhan G. Soft drinks, fructose consumption, and the risk of gout in men: prospective cohort study. BMJ. 2008;336(7639):309–312.
6. World Anti-Doping Agency. The World Anti-Doping Code International Standard: Prohibited List. Montreal: WADA; оновлюється щорічно.