Evaluating the performance of urine conductivity as screening for early stage chronic kidney disease.

BACKGROUND: This study aimed to determine if urine conductivity (Cond) is better for screening early stage chronic kidney disease (CKD) instead of the currently routinely used parameters of urine creatinine (UCr), urine osmolality (Osmo), urine specific gravity (SpGr), and urine protein (UP). METHODS: One hundred and forty participants (86 male, 54 female) with eGFR > 60 were grouped as either early stage CKD (kidney damage longer than 3 months with either structural or functional abnormalities [n = 72]) or the control group (without CKD and without kidney damage or functional abnormalities [n = 681]). Sensitivty (Sn) and specificity (Sp) of UP and the ROC curves were calculated. The area under the curve (AUC) with 95% confidence interval (CI) was used to compare Cond, UCr, Osmo, and SpGr. Pearson's correlation was used to analyze the correlation between Cond and UCr, Osmo, and SpGr in the early stage CKD group. RESULTS: The Sn and Sp of UP were 22.2% and 92.6%, respectively. By ROC analysis, Cond had the largest AUC (0.752, 95% CI: 0.672-0.832), with 52.9% Sn and 86.1% Sp. Pearson's correlation showed that the coefficient (p < 0.01) of Cond to UCr, Osmo, and SpG were 0.696, 0.907, and 0.820, respectively. CONCLUSIONS: Cond has better screening ability than UP for early stage CKD and may be a potential surrogate parameter for Osmo, SpGr and UCr.