The effect of normal saline on renal function and electrolytes in women with preeclampsia

Due to a nationwide shortage of Ringer's lactate, normal saline became the intravenous fluid of choice at our institution in May 2018. Recent studies have shown that the administration of normal saline in critically ill patients may have adverse renal effects.

Our objective was to evaluate the renal function effects; if any, of normal saline administered to women with preeclampsia receiving magnesium sulfate.

This is a prospective observational study of women identified with preeclampsia with severe features, requiring magnesium sulfate prophylaxis. The amount of normal saline administered was calculated and a basic metabolic panel was surveyed 12 h after initiation of magnesium sulfate prophylaxis. Laboratory analytes were examined according to the volume of intravenous normal saline received, including a comparison to those women who did not receive normal saline, to determine the impact of parameters after 12 h of magnesium sulfate prophylaxis.

From May 2018 to November 2018, a total of 233 patients receiving magnesium sulfate were identified, 184 of which had received intravenous normal saline. No differences were identified at 12 h in serum chloride or creatinine between those patients who received intravenous normal saline and those who did not. This finding persisted when serum chloride and creatinine were analyzed across quartiles of normal saline received. Interestingly, serum calcium was found to decrease with increasing serum magnesium (p < .001). This association was also dependent upon the amount of intravenous fluids received (p < .001) when controlling for serum magnesium.

Renal function indices were preserved despite the introduction of normal saline with oxytocin into routine practice. No dose-response relationship was identified when serum chloride and creatinine were analyzed across quartiles of normal saline received. Interestingly, serum calcium levels were noted to decline with both the amount of intravenous fluid received as well as with increasing serum magnesium levels.