FRI0248 Validity of random urinary uric acid-to-creatinine ratio for estimating 24-hour urine uric acid excretion in patients with gout. (12th June 2018)

• Record Type: Journal Article
• Authors: Choi, S.; Moon, S.-J.; Kang, E.-J.; Lee, K.-H.
• Is Part Of: Annals of the rheumatic diseases. Volume 77(2018)Supplement 2
• Page Start: 664
• Page End: 665
• Publication Date: 2018-06-12
• Subjects: Rheumatism -- Periodicals; 616.723005
• DOI: 10.1136/annrheumdis-2018-eular.5005
• Languages: English
• ISSNs: 0003-4967

Abstract

Abstract : Background: Gout is one of a heterogeneous group of diseases related to hyperuricemia. The measurement of 24 hour urinary uric acid excretion is frequently used to evaluate disease status and select drugs that lower uric acid level. However, 24 hour urine collection is inconvenient and frequently unreliable, due to errors in collection. Therefore, a simpler alternative to the 24 hour urine collection is needed. Objectives: We investigated the utility of the random urine uric acid-to-creatinine (UA/CR) ratio in predicting 24 hour urine uric acid excretion in patients with gout. Methods: Ninety patients with gout without any use of uric acid lowering agents were enrolled in this study. The mean age was 50.0±16.7 years old and the male patient was 90.0% (81/90) of all participants. For the evaluation of uric acid excretion and renal function, patients were collected 24 hour urine. Random urine uric acid and creatinine specimens were gained on the same day of 24 hour urine collection. Chronic kidney disease was defined as a creatinine clearance (CCr) level of less than 60 ml/min/1.73m 2 measured in 24 hour urine collection sample. Excretion of more than 600 mg of uric acid in the 24 hour urine sample was defined as uric acid over-excretion. Results: Mean serum uric acid level was 7.73±1.89 mg/dl, and the mean 24 hour uric acid excretion was 666.5±236.2 mg. The random urinary UA/CR ratio showed positive correlation with 24 hour urine uric acid excretion ( γ =0.398, p < 0.001). Correlation between these two variables was also found in the patients with chronic kidney disease ( γ =0.762, p=0.028 In the linear regression analysis, absolute 24 hour urine uric acid excretion was estimated to be 581 x (random urinary UA/Cr)+432 (p < 0.001, adjusted R 2 =0.398). The best cut-off value for the random urinary UA/Cr ratio to distinguish between uric acid over-excretion and normal uric acid excretion was 0.342, with a sensitivity of 74.1%, specificity of 66.7%. The areas under the curves (AUCs) of the random urine UA/CR ratio was 0.763 [95% confidence interval (CI), 0.665–0.861, p < 0.001]. Conclusions: The random urine UA/CR ratio correlated with 24 hour urine uric acid excretions in patients with gout. The best cut-off random urine UA/CR ratio value to discriminate uric acid over-excretion was 0.342, with a sensitivity of 74.1% and a specificity of 66.7%. The random urine UA/CR ratio would be a useful predictor to detect patients with urinary uric acid underexcretion, who could then be treated with uricosuric drugs. Disclosure of Interest: None declared