J Korean Med Sci.  2020 Apr;35(13):e95. 10.3346/jkms.2020.35.e95.

The Utility of the Random Urine Uric Acid-to-Creatinine Ratio for Patients with Gout Who Need Uricosuric Agents: Retrospective Cross-Sectional Study

• Choi ST
• Song JS
• Kim SJ
• Kim CH
• Moon SJ

• KMID: 2509602
• DOI: http://doi.org/10.3346/jkms.2020.35.e95

Abstract

Background
The 24-hour uric acid excretion measurement is important in assessing disease status and helping to select the appropriate uric acid-lowering agent for patients with gout, however, it is inconvenient. The authors investigated the efficacy of the random urine uric acid-to-creatinine (UA/CR) ratio to screen the patients who under-secreted 24-hour urine uric acid.
Methods
This was a retrospective cross-sectional study. Ninety patients with gout, without undergoing uric acid-lowering treatment were enrolled. Twenty-four-hour urine and random urine samples were obtained on the same day. Six hundred mg of uric acid in the 24-hour urine sample was used as a standard for distinguishing between over and under-excretion groups.
Results
The random urinary UA/CR ratio showed positive correlation with 24-hour urine uric acid excretion (γ = 0.398, P < 0.001). All the patients with the random UA/CR less than 0.2 excreted less than 600 mg uric acid in 24-hour urine collection. When the random urine UA/CR ratio < 0.2 was regarded as a positive result, the positive predictive value, negative predictive value, sensitivity, and specificity in the uric acid under-excretion were 100% (8 of 8), 64.6% (53 of 82), 21.6% (8 of 37), and 100% (53 of 53), respectively.
Conclusion
There is a moderate positive correlation between the random urinary UA/CR ratio and 24-hour urine uric acid excretion, so that UA/CR ratio may not be a good predictor of 24-hour urine uric acid excretion. However, the random urine UA/CR ratio 0.2 can be a useful predictor to screen the gouty patients who need to be treated with uricosuric drugs.

Keyword

Urine; Uric Acid; Creatinine; Gout; Uricosuric Agents

Figure

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  Fig. 1 Receiver operation characteristic curves for the random urine uric acid-to-creatinine ratio to discriminate 24-hour urine uric acid excretion > 600 mg.

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  Fig. 2 The correlations between 24-hour urine uric acid excretion and the random urine UA/CR.UA/CR = uric acid-to-creatinine ratio.

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