Background Hypouricemia is defined as a serum uric acid concentration of less than 2.0 mg/dL and is characterized by increased uric acid clearance or decreased uric acid production. Causes of hypouricemia may be a renal uric acid transporter gene defect or be related to medical diseases or medications that enhance uric acid excretion [1, 2]. A study conducted in Korea reported that among a total of 909 subjects, 30 (3.3%) had hypouricemia, and the SLC22A12 mutation was identified in 11 out of 30 patients with hypouricemia . However, few studies of factors affecting hypouricemia have been conducted on Koreans.
Objectives We therefore aimed to investigate the prevalence and possible causes of hypouricemia in the Korean population and to compare our findings to published results of other populations.
Methods We retrospectively examined serum uric acid levels from 29,672 subjects who visited outpatient clinics (n=23,228) or were admitted to a tertiary care hospital (n=6,444) between January 2012 and December 2012. These subjects had their uric acid values measured at least once during the one-year period. All individuals with hypouricemia (serum uric acid <2.0 mg/dL, n=424) were reviewed with respect to medical drug history and concomitant diseases identified previously as being associated with hypouricemia.
Results The prevalence of hypouricemia among inpatients was 4.6% (299/6,444) and that among outpatients was 0.5% (125/23,228), for an overall prevalence of 1.4% (424/29,672). The possible causes associated with hypouricemia were solid or hematologic malignancies (n=86), diabetes mellitus (n=56), and therapeutic drugs (n=29). The medications were allopurinol (n=11), angiotesin II receptor blockers (n=10), salicylates (n=6), febuxostat (n=1), and warfarin (n=1). In remaining 226 individuals, the cause of hypouricemia was not identified. Overall, the prevalence and causes of hypouricemia were similar to those among the European population.
Conclusions Hypouricemia is relatively common in the Korean population. The possible causes associated with hypouricemia are related to underlying diseases and medications, and idiopathic hypouricemia such as hereditary renal hypouricemia does not appear to be rare. Although we cannot definitely conclude because fractional excretion of uric acid was not measured, genetic testing is considered necessary for patients with no known causal diseases or medications.
Bairaktari ET, Kakafika AI, Pritsivelis N, Hatzidimou KG, Tsianos EV, Seferiadis KI, et al. Hypouricemia in individuals admitted to an inpatient hospital-based facility. Am J Kidney Dis 2003;41:1225-32.
Bugdayci G, Balaban Y, Sahin O. Causes of hypouricemia among outpatients. Labmedicine 2008;39:550-52.
Lee JH, Choi HJ, Lee BH, Kang HK, Chin HJ, Yoon HJ, et al. Prevalence of hypouricemia and SLC22A12 mutations in healthy Korean subjects. Nephrology 2008;13:661-6.
Acknowledgements This work was supported by the research fund of Hanyang University (HY-2012-MC).
Disclosure of Interest None declared
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