Age-specific reference intervals for liver function tests in healthy neonates, infants, and young children in Iran

Area of Science:

• Pediatric Biochemistry
• Clinical Chemistry
• Reference Interval Determination

Background:

• Establishing accurate reference intervals (RIs) for liver function tests (LFTs) is essential for pediatric clinical practice.
• Previous RIs for LFTs in Iranian children were unavailable, necessitating this study.
• This research addresses a critical gap in pediatric diagnostic standards in Iran.

Purpose of the Study:

• To determine the reference intervals for key liver function tests in healthy Iranian children.
• To provide age-specific reference data for alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), direct bilirubin, and total bilirubin.
• To enhance the clinical interpretation of LFT results in the pediatric population.

Main Methods:

• A cohort of 344 healthy children aged 3 days to 30 months was recruited.
• Serum levels of ALT, AST, ALP, direct bilirubin, and total bilirubin were quantified.
• Reference intervals were established following the Clinical and Laboratory Standards Institute (CLSI) Ep28-A3 guidelines.

Main Results:

• Significant age-specific variations were observed for ALT, ALP, direct bilirubin, and total bilirubin, but not for AST.
• Infants aged 0 to <5 months showed notably higher ALT and ALP levels compared to older children.
• Direct and total bilirubin levels were markedly elevated in early infancy, decreasing by approximately 50% in subsequent age groups.

Conclusions:

• The established reference intervals provide novel, age-specific data for LFTs in Iranian children.
• These findings are expected to improve the accuracy of clinical interpretations of biochemical tests in neonates and children.
• The data will be valuable for clinical laboratories serving pediatric populations, particularly in Iran and similar regions.