Abstract
Classification of hyperuricemia is important for the selection of appropriate treatment, however, the classification by using 60-minute (60-min)or 24-hour (24-h) urine collection in outpatients is not conventional. The aim of the present study was to compare the classification by using 60-min and 24-h urine collection and the urinary uric acid/urinary creatinine (UUA/UCr) ratio determined by spot urine. Subjects were 9 hypertensive inpatients with hyperuricemia (3 females and 6 males, mean age : 62±15 (SD) years), who did not take diuretics or UA-lowering drugs. Patients underwent 60-min and 24-h urine collection to determine UA metabolism advocated by the guidelines for the treatment of hyperuricemia and gout. We compared the classification of hyperuricemia by 60-min urine collection to that obtained by 24-h urine collection or by the UUA/UCr ratio in spot urine. Based on 60-min urine collection, the decreased UA excretion type was found in 77.8% and 22.2% showed the overproduction type. On the other hand, the decreased UA excretion type and mixed type were found in 88.9 and 22.2%, respectively, by 24-h urine collection. When the cutoff values of 0.5, 0.6, and 0.7 for the UUA/UCr ratio of spot urine were adopted, the decreased UA excretion type was found in 66.7, 88.9 and 100%, respectively. The consistent classification by both 60-min and 24-h methods was obtained in 66.7% of the patients. On the contrary, the consistent classification by both 60-min and spot urine UUA/UCr ratio methods with cutoff values of 0.5, 0.6, and 0.7 were obtained in 66.7, 66.7 and 77.8%, respectively. In conclusion, the UUA/UCr ratio determined by spot urine seems to be useful and conventional in clinical practice to classify hyperuricemia.
