Seasonal influence on the renal function in hospitalized elderly patients

Background: Elderly adults are more vulnerable to heat-induced illness because of dysfunctional thermoregulatory mechanisms, chronic dehydration, medications, and diseases involving the systems that regulate body temperature. We hypothesized that extensive loss of fluids in a hot and dry climate in the summer months may lead to impaired renal function in elderly patients. The aim of the study was to determine the impact of the season of admission on renal function and the development of acute kidney injury in elderly patients. Methods: A retrospective observational cohort study on all patients older than 65 with creatinine level ≤ 2.0 mg/dL who were hospitalized twice (in the summer and in winter) in 2010-2011. The outcome was incidence of acute kidney injury. Results: The study cohort included 1107 consecutive patients hospitalized in the summer and in the winter months. The biochemical parameters of impaired renal function were more prominent in the summer as compared to the winter months in the whole cohort of patients and especially in patients with hypertension, diabetes mellitus and heart failure, and in patients treated with thiazide diuretics, ACE-inhibitors and ARBs. The most common reason for hospitalization in patients developing AKI in the summer was febrile disease and sepsis and in the winter heart, failure. Conclusions: Extensive fluids loss in a hot and dry climate in the summer months leads to mild impaired renal function in elderly patients. However, this influence is not clinically significant probably due to compensatory mechanisms for the preservation of renal function.