What is Hypouricemia?
A Disease Similar to Exercise-Induced Acute Renal Failure
While there are no symptoms, renal hypouricemia may cause complications due to low uric acid levels, such as exercise-induced acute renal failure and urolithiasis. A disease that shows similar symptoms to exercise-induced acute renal failure is described below.
Exercise-Induced Acute Renal Failure and Rhabdomyolysis
Exercise-induced acute renal failure shows symptoms such as severe upper and lower back pain, nausea, vomiting, or decrease of urine volume after several hours to one day after an intense exercise. Similar symptoms are also observed for rhabdomyolysis. Rhabdomyolysis is a disease in which cell destruction occurs as a result of skeletal muscle damage, leading to elution of substances composing the muscles into the blood. Once these eluted substances reach the kidney, acute renal failure is induced.
Rhabdomyolysis is caused not only by excessive exercise, but also by infection, effects of drugs, or heat stroke. Subjective symptoms of rhabdomyolysis include muscle pain or weakness of the limbs, or change of urine color to dark brown
Rhabdomyolysis increases the flow of an enzyme called creatine kinase (CK) and a protein called myoglobin from the muscles into the blood to a value that is 10 times higher than the normal value. However, exercise-induced acute renal failure induces only a slight increase in these substances if any.
When exercise-induced acute renal failure is developed as a complication of renal hypouricemia, blood uric acid levels temporarily increase to a normal level. As a result, there is a risk that renal hypouricemia may be overlooked when a blood test is conducted during the onset of exercise-induced acute renal failure.
Confirmation of Exercise-induced Acute Renal Failure
Discrimination between exercise-induced acute renal failure and rhabdomyolysis is made based on the presence or absence and the degree of increase of CK or myoglobin in the blood and the transition of levels of myoglobin and uric acid in urine. In addition, the symptoms of exercise-induced acute renal failure are also similar to that of renal calculus. Since exercise-induced acute renal failure tends to show repeated onset, patients might have experienced similar symptoms in the past. Try to remember what you had done a few hours before the onset of the symptoms. Exercise-induced acute renal failure as a complication of renal hypouricemia is considered likely to occur when intense anaerobic exercises such as sprinting or strength training is combined with dehydration or administration of NSAID*.
The prognosis of exercise-induced acute renal failure is generally favorable, and patients can return to normal life with recovery of renal functions after one week to one month of treatment. Although there are some cases that require dialysis, it is only done temporarily.
* NSAID: Nonsteroidal anti-inflammatory drug (drug which has anti-inflammatory, analgesic, or antipyretic action)