Developmental changes in urinary coproporphyrin ratio in premature infants
Yusei Nakata1,2, Hitoshi Okada2, Susumu Itoh2
1Department of Pediatrics, Kochi Health Science Center, Kochi-City, Kochi, Japan.
Insights
The urinary coproporphyrin ratio (UCP(I/[I+III])) is higher in premature infants at birth, decreasing within the first week. This biomarker reflects the function of the ABC C2 transporter in conjugated bilirubin export.
Area of Science:
- Neonatal Physiology
- Biochemistry
- Clinical Chemistry
Background:
- Premature infants exhibit elevated conjugated bilirubin due to immature glucuronidation.
- Adenosine triphosphate binding cassette subfamily C member 2 (ABCC2) plays a role in bilirubin excretion.
- The urinary coproporphyrin I/(I+III) ratio (UCP(I/[I+III])) serves as a biomarker for ABCC2 function.
Purpose of the Study:
- To investigate developmental changes in UCP(I/[I+III]) in premature infants.
- To assess the association between UCP(I/[I+III]) and postnatal and corrected gestational age.
Main Methods:
- Study included 21 premature infants (25–32 weeks gestation).
- Urine samples collected within 24 hours, 1 week, and 3–4 weeks post-birth.
- High-performance liquid chromatography used to calculate UCP(I/[I+III]); exclusions for liver dysfunction, cholestasis, UTI, or chromosomal abnormalities.
Main Results:
- Average UCP(I/[I+III]) was 0.84 at birth, 0.61 at 1 week, and 0.65 at 3–4 weeks.
- UCP(I/[I+III]) was significantly higher within 24 hours of birth compared to later time points.
- No significant correlation found between UCP(I/[I+III]) and corrected gestational age.
Conclusions:
- UCP(I/[I+III]) levels are elevated in premature neonates immediately after birth.
- A significant decrease in UCP(I/[I+III]) occurs by 1 week of age.
- UCP(I/[I+III]) remains low and stable up to 4 weeks post-birth, indicating early functional changes in ABCC2.
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.
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