Use of urinary indexes in renal failure in the newborn
E. N. Ellis and W. C. Arnold
Causes of renal failure and urinary indexes were recorded in 45 neonates
with oliguria and uremia. Twenty (44%) had ischemic renal damage; nine of
these infants recovered and 11 died. Eight infants (18%) had various other
causes of renal insufficiency. Determination of serum BUN or creatinine
concentrations did not differentiate between these groups. Fractional
excretion of sodium (FENa) and renal failure index (RFI) determined on
serum and first-voided urine samples were statistically different between
the neonates with prerenal uremia and the neonates with ischemic renal
damage, although there was overlap between the groups. A neonate with an
FENa less than 2.5% and an RFI less than 2.5 is said to have prerenal
uremia. An FENa greater than 2.5% or an RFI greater than 2.5 in a neonate
suggests ischemic renal disease; however, some neonates with prerenal
uremia may have values in this range.
