Urinary Hypoxanthine as a Measure of Increased ATP Utilization in Late Preterm Infants.

Objective: To examine the effect of neonatal morbidity on ATP breakdown in late preterm infants.

Study design: Urinary hypoxanthine concentration, a marker of ATP breakdown, was measured from 82 late preterm infants on days of life (DOL) 3 to 6 using high-performance liquid chromatography. Infants were grouped according to the following diagnoses: poor nippling alone (n = 8), poor nippling plus hyperbilirubinemia (n = 21), poor nippling plus early respiratory disease (n = 26), and respiratory disease alone (n = 27).

Results: Neonates with respiratory disease alone had significantly higher urinary hypoxanthine over DOL 3 to 6 when compared with neonates with poor nippling (P = .020), poor nippling plus hyperbilirubinemia (P < .001), and poor nippling plus early respiratory disease (P = .017). Neonates with poor nippling who received respiratory support for 2 to 3 days had significantly higher hypoxanthine compared with infants who received respiratory support for 1 day (P = .017) or no days (P = .007).

Conclusions: These findings suggest that respiratory disorders significantly increase ATP degradation in late premature infants.