Endothelin-1 levels and renal function in newborns of various gestational ages

Abstract.
BACKGROUND: Renal failure is common in the NICU; Acute Kidney Injury (AKI) occurs in 8–24% of admissions. Although AKI is preventable with early diagnosis, no reliable AKI biomarkers exist. Endothelin-1 (ET-1) has been implicated in renal pathogenesis, and elevated urinary ET-1 (uET-1) levels may correlate with progression of renal dysfunction. The study objectives were to determine whether uET-1 levels correlate with renal function parameters and/or fetal growth restriction, and if uET-1 is a potential neonatal AKI biomarker.
METHODS: Sixty-three neonates were enrolled and divided into gestational age (GA) groups by weeks: 1) (24–30 6/7; n  = 24); 2) (31–36 6/7; n  = 26); and 3) (37–42; n  = 13). Additional preterm subgroups for fetal growth restriction analysis included: 1) Appropriate for GA (AGA; n  = 40), and 2) Small for GA (SGA; n  = 10). ET-1 levels, measured using enzyme linked immunosorbent assay, were collected at birth (cord blood) and 24 h ( ± 4) of life (blood/urine).
RESULTS: No correlation was found between uET-1 and blood plasma levels at birth (r  = 0.15; p  > 0.05) or 24 h (r  = 0.17; p  > 0.05). uET-1 negatively correlated with GA (r  = –0.44; p  < 0.001) and GFR (r  = –0.34; p  < 0.01). uET-1 levels did not correlate with creatinine (r  = 0.13; p  > 0.05), BUN (r  = 0.19; p  > 0.05), BUN/Cr ratio (r  = 0.15; p  > 0.05), or urinary output (r  = 0.12; p  > 0.05). In fetal growth restriction subgroup analyses: uET-1 levels negatively correlated with GFR in the PT–AGA subgroup (r  = –0.38; p  = 0.017), but not with PT–SGA (r  = 0.01; p  > 0.05).
CONCLUSION: Plasma and uET-1 levels did not correlate; therefore, renal ET-1 excretion may reflect renal ET-1 production. uET-1 levels correlated negatively with GA and GFR. uET-1 may be a marker of impaired neonatal circulatory regulation and consequent renal injury.