Correlation of 24-hour urine sodium, potassium and calcium measurements with spot urine

Abstract

In this study, we analyzed the correlation of sodium(Na), potassium(K) and calcium(Ca) amounts with spot urine(SU) and 24-hour urine(24-HU) collected as 8-hour portions. 21 hypertensive patients and 21 normotensive individuals were enrolled in the study. Na, K and Ca were studied in three sequential 8-hour urine samples and with the sum of three, 24-HU samples of the cases. Sodium/creatinine, potassium/creatinine, and calcium/creatinine were studied in fasting SU and serum Na, K and creatinine were studied. A significant correlation was found between the SU sodium/creatinine ratio and the Na amount in each 8-hour urine collections, and the Na amount in the 24-hour urine in hypertensive patients, the control group, and when all patients were evaluated together. When all group were evaluated together for Ca, a significant correlation was determined between the SU calcium/ creatinine ratio and the Ca amount in all three 8-hour urine collections. The Na amount in the 24-HU may be estimated both with the SU Na/creatinine ratio and the 8-hour urine collection; SU does not have clinical significance for potassium. However, it may be estimated with 8-hour urine collections; SU may help roughly for calcium, and the collected urine gives higher correlation coefficients.