SAT-207 Evaluation of Kidney Protection Effect by Drinking Water Using Urine Specific Gravity

Abstract

Mechanism of kidney protection effect by drinking water is still unknown. Because ADH secretion by dehydration is considered to be a factor of deteriorating renal function, we aimed to test the hypothesis that people with high urinary osmotic pressure (HUO group) have more rapidly decrease kidney function than low people (LWO group). This was a retrospective observational study of a single facility. From January 2009 to December 2015, we obtained medical records of patients visiting our department of internal medicine. Urine osmotic pressure was substituted by urine specific gravity. HUO group defined that urine specific gravity is 3 times more of above 1.030 with urine protein and glucose negative. Also LUO group define as 3 times more of below 1.005 Those corresponding to both groups, 18 years old and under are excluded. Patient who started dialysis discontinued at the time. We evaluated both groups with background factor by using propensity score and then evaluated by the annual decline rate of estimated GFR (eGFR), the time-to-event analysis for 30% decline of eGFR. A propensity score was calculated by gender, age, time averaged HbA1C level, initial eGFR and using renin- angiotensin-aldosterone system inhibitors drugs. Among 7592 people, 9.2% meet the criteria, 158 people were HUO group, 542 people were LWO group. After matching, 140 people were included in each group, average age 62.0 years old, male 65.7%, average observation period 6.9year, time-average HbA1c 6.4% and initial eGFR 75.6ml / min / 1.73 m2. Although there was a difference, the annual decline rate of eGFR was no significant difference (LUO group : -1.0 ± 3.2 vs HUO group : -1.5 ± 2.7 ml / min / 1.73 m2, p = 0.14). In the time-to-event analysis for 30% decline of eGFR, HUO group demonstrated a little faster renal function decline than LWO group (Fig1. log-rank test p = 0.026). In this study, the effect of kidney protection by drinking water was slight.