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Alpha 1-fetoprotein (AFP) reference values in infants up to 2 years of age
M E Blohm1, D Vesterling-Hörner, G Calaminus
1Department of Paediatric Haematology and Oncology, Children's Hospital, Heinrich Heine University Medical Centre, Düsseldorf, Germany.
Insights
Serum alpha-fetoprotein (AFP) levels are significantly higher in newborns, declining rapidly in the first month. Infant AFP levels remain elevated until age two, not reaching adult ranges.
Area of Science:
- Pediatrics
- Biochemistry
- Neonatology
Background:
- Serum alpha-fetoprotein (AFP) is a crucial biomarker with established reference ranges in adults.
- Understanding AFP kinetics in infants is essential for accurate interpretation of clinical findings and disease diagnosis.
Purpose of the Study:
- To establish normative serum AFP reference values for infants up to two years of age.
- To identify factors influencing AFP levels during early development.
Main Methods:
- Analysis of 524 infant serum samples collected at the University Hospital Düsseldorf.
- Exclusion of samples from infants with known factors associated with AFP elevation.
- Statistical analysis to determine mean levels, decline rates, and 95.5% intervals.
Main Results:
- At birth, mean AFP levels were 41,687 ng/ml in term infants and 158,125 ng/ml in premature infants.
- AFP levels halved approximately every 5.1 days in term infants during the first four weeks.
- Between 180 and 720 days, AFP levels up to 87 ng/ml were within the 95.5% interval, with a mean of 8 ng/ml.
Conclusions:
- Infant serum AFP levels exhibit a distinct pattern, characterized by high initial values and a significant postnatal decline.
- Established reference ranges are crucial for differentiating physiological AFP changes from pathological elevations in infants.
- Infants do not attain adult AFP levels by two years of age, highlighting the need for age-specific interpretation.
Abstract:
The aim of this study was to establish reference values and factors associated with serum AFP elevation in infants. Five hundred twenty-four samples collected from infants up to the age of 2 years at the University Hospital Düsseldorf (Germany) were analyzed. At birth mean serum AFP levels were 41,687 ng/ml in 256 term babies and 158,125 ng/ml in 90 premature babies born before the 37th gestational week, excluding samples from children with factors known to be associated with AFP elevation. In the first 4 weeks of life, AFP levels decreased by 50% in 5.1 days in term babies. Between day 180 and 720 of life, AFP levels up to 87 ng/ml were within the 95.5% interval (assumed logarithmic normal distribution) with a mean of 8 ng/ml without a further decline. By the age of 2 years the infants of this study had not reached adult serum AFP levels (0-6 ng/ml).