Developmental changes in urinary coproporphyrin ratio in premature infants

Abstract

Background: Premature infants have a high concentration of conjugated bilirubin in their blood, although they have a poor glucuronide conjugation of bilirubin. This may be due to developmental changes in the function of adenosine triphosphate binding cassette subfamily C member 2, which is involved in the cellular export of conjugated bilirubin. In the present study, we examined the developmental changes in the urinary coproporphyrin I/(urinary coproporphyrin I+ urinary coproporphyrin III) ratio (UCP (I/ [I + III])), a known biomarker for adenosine triphosphate binding cassette subfamily C member 2 function, in premature infants. Method: Twenty-one premature infants born between 25 and 32 weeks of gestation were included in the study. Urine samples were collected within 24 h of birth, and at 1 week and 3-4 weeks after birth. The samples were analyzed by high-performance liquid chromatography to calculate UCP (I/ [I + III]) to examine its association with postnatal age and corrected gestational age. Subjects were excluded if they had liver dysfunction, cholestasis, urinary tract infection, or chromosomal abnormalities. Results: The average UCP (I/ [I + III]) within 24 h of birth, at 1 week, and at 3-4 weeks after birth was 0.84, 0.61, and 0.65, respectively. The UCP (I/ [I + III]) within 24 h of birth was significantly higher than that measured at 1 week or 3-4 weeks after birth. There was no significant correlation between UCP (I/ [I + III]) and the corrected gestational age. Conclusion: The UCP (I/ [I + III]) was higher within 24 h of birth. It decreased 1 week after birth and remained low without any significant changes for up to 4 weeks after birth.

Gestational age, sex, and time affect urine biomarker concentrations in extremely low gestational age neonates

“…The term postmenstrual age (PMA) is used to define time from conception (GA plus chronological age). The changes in urine biomarkers as a function of PMA in premature neonates have been reported for oxytocin 25 and corpoporyphin, 26 but not for urine candidate AKI biomarkers.…”