USEFULNESS OF FRACTIONAL EXCRETION OF SODIUM IN CRITICALLY ILL PRETERM NEWBORNS

The purpose of this prospective study was to measure the fractional ex cretion of sodium (FENa) in critically ill pre-term newborns (PTNB) in order to determine its cut point in the diagnosis of acute renal fail ure (ARF). This study included 52 newborns and was conducted from May, 1994 to May, 1995. Patients were divided in two groups: patients with out ARF in group A (n = 47) and patients with ARF in group B (n = 5). No statistically significant differences were found in birth weight, e xtrauterine life span, serum sodium levels, urine creatinine and urina ry volumes between the two groups, but there was a difference in gesta tional age, urinary sodium concentration and serum creatinine levels. Sensitivity and specificity were determined, and the critical level of FENa was 4% or greater for ARF diagnosis. The average FENa value for Group A was 1.4 +/- 1.4 % with a median of 0.92 %. In Group B, average FENa was 6.9 +/- 2.9 % with a median of 8.5 % (P < 0.001). We conclud e that FENa is a valuable tool for the assessment of renal function in critically-ill PTNB, in spite of all other factors present in this po pulation that could modify its values.