Severe acute hypophosphatemia during renal replacement therapy adversely affects outcome of critically ill patients with acute kidney injury

Hypophosphatemia during renal replacement therapy (RRT) is common in critically ill patients with acute kidney injury (AKI). The clinical consequences of RRT-induced phosphate depletion are not well defined in this patient population, and there is no evidence that intravenous sodium phosphate supplementation (PS) prevents the clinical sequelae of acute hypophosphatemia. The purpose of this retrospective analysis of the Acute Renal Support Registry of the University of Munich was to examine the association between severe hypophosphatemia and severity of and recovery from AKI. 289 ICU patients with AKI on intermittent hemodialysis (IHD) were included in the study. One hundred and forty-nine patients received PS during IHD. Outcomes were short-term (at discharge) and long-term (at 1 year) recovery of renal function and mortality. The two patient groups did not differ in demographics, clinical features, renal characteristics, and frequency of hypophosphatemia at initiation of IHD. Without PS, the frequency of hypophosphatemia increased from 20 to 35%. Severe hypophosphatemia was found in 50% of these patients. By comparison, PS was not associated with an increased frequency of hypophosphatemia. Compared with patients with acute phosphate depletion, patients receiving PS developed less oliguria during IHD, had shorter duration of AKI, higher incidence of complete renal recovery at discharge, and a lower risk of de novo chronic kidney disease. Hypophosphatemia was associated with higher all-cause in-hospital mortality and higher risk of long-term mortality. This multicenter study indicates for the first time that hypophosphatemia during IHD adversely affects short- and long-term outcome of critically-ill patients with AKI. The clinical consequences of the acute hypophosphatemic syndrome may be prevented by PS.