Infant liver biochemistry is different than current laboratory accepted norms

The purpose is to study liver biochemistry in a well-defined cohort of term infants. The methods include healthy term infants (n = 619) provided blood samples at 3 and 6 months of age when participating to the DIABIMMUNE study. The infants were followed up at clinical study visits 3, 6, 12, 18, 24, and 36 months the participation rate being 88.6% at the end of follow-up, while none disclosed any signs of a liver disease. The serum levels of serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), gamma-glutamyl transferase (GGT), total bilirubin (BIL), and conjugated bilirubin (BIL-conj) were determined using Siemens Atellica CH 930 analyzers. The results are at 3 months of age, the upper 90% CI for ALT, AST, ALP, GGT, BIL, and BIL-conj were higher than the current upper reference limits in our accredited hospital laboratory. At 6 months, the upper 90% CIs for ALT had declined but was still higher than the cut-offs for a raised value. The upper 90% CI for AST remained as high as at 3 months, whereas ALP, BIL-conj, and GGT had decreased close to the current cut-offs. The type of feeding was associated with the levels of liver biochemistry. Exclusively or partially breastfed infants showed higher ALT, AST, BIL, and BIL-conj values at 3 months than formula-fed. Breastfed infants had higher AST, Bil, and Bil-conj values also at 6 months.  Conclusion: We encourage setting appropriate reference ranges for liver biochemistry for the first year of life and to note the type of feeding. What is Known: • Healthy infants may show higher values of liver biochemistry during their first year of life than in later life. • It has been speculated that type of feeding may play a role in liver biochemistry levels among infants. What is New: • In a cohort of healthy infants, several analytes of liver biochemistry were higher than the currently used upper reference limits at 3 and 6 months of age, and exclusively or partially breastfed infants showed higher values than formula-fed. • The findings address the importance of setting appropriate reference ranges for liver biochemistry for the first year of life.