Diagnostic usefulness of the random urine Na/K ratio in cirrhotic patients with ascites: a pilot study

doi:2010.16.1.66

Korean J Hepatol > Volume 16(1); 2010 > Article

The Korean Journal of Hepatology 2010;16(1): 66-74.
doi: https://doi.org/10.3350/kjhep.2010.16.1.66

Diagnostic usefulness of the random urine Na/K ratio in cirrhotic patients with ascites: a pilot study

Jae Eun Park, M.D., Chang Hyeong Lee, M.D., Byung Seok Kim, M.D., Im Hee Shin, Ph.D.1

Department of Internal Medicine and 1Medical Statistics, Catholic University of Daegu School of Medicine, Daegu, Korea

ABSTRACT

Background/Aims
Twenty-four hour urinary sodium excretion (24-h UNa) of greater than 78 mmol/day is important in the management of cirrhotic ascites. Although the random urine sodium-to-potassium ratio (UNa/K) is strongly correlated with 24-h UNa, and approximately 95% of patients with a random UNa/K greater than 1 have 24-h UNa greater than 78mmol, few data have been published on the correlation between 24-h UNa and random UNa/K. We evaluated diagnostic value of morning and afternoon random UNa/K (AM UNa/K and PM UNa/K, respectively) with 24-h UNa. Methods: A total of 42 male patients were enrolled from October 2007 to March 2008. Each patient collected 5 mL of urine twice at random times during 24-h urine collection (at 10-12 a.m. and 3-5 p.m.). ROC curve analysis was performed to evaluate the feasibility of AM and PM UNa/K for differentiating 24-h UNa greater than 78mmol/day. Results: Forty patients with a 24-h urinary creatinine of greater than 15 mg/kg were analyzed. The 24-h UNa, AM UNa/K, and PM UNa/K were 107.9±91.2mmol (mean±SD), 3.44±3.64, and 3.97±4.60, respectively. When compared with 24-h UNa greater than 78 mmol, AUROC values for AM and PM UNa/K were 0.861 (95% CI, 0.715-0.950) and 0.929 (95% CI, 0.802-0.986), respectively (P=0.0001). No difference was found between the AUROC for AM and PM UNa/K (95% CI, -0.161-0.153, P=0.113). UNa/K greater than 1.25 was sensitive and specific for prediction of 24-h UNa greater than 78 mmol. Conclusions: The results suggest that anytime random UNa/K greater than 1.25 is an accurate, cost-effective, and convenient method for replacing 24-h UNa. Large multicentered cohort studies are needed to confirm our results. (Korean J Hepatol 2010; 16:66-74)

KeyWords: Liver cirrhosis; Ascites; Complications; Urine; Sodium