Objective: Alpha fetoprotein (AFP) is an important tumor marker in childhood. However, AFP levels remain high during the first few months of life, making clinical interpretation difficult in this period. The aim of the present study is to determine normal AFP levels in healthy full-term neonates and infants followed-up at Kocaeli University Hospital, Department of Pediatrics.

Materials and Methods: Healthy full-term neonates born in Kocaeli University Hospital and <12 month-old infants attending the well baby outpatient clinic were enrolled in the study. Blood samples were drawn from the umbilical cord vein at delivery or peripheral vein after delivery. Serum AFP concentration was determined by solid phase, two-site chemiluminescent immunometric commercial diagnostic assay.

Results: Ninety-four neonates with a gestational age of 37-41 weeks and <12 month-old infants (48 male, 46 female) were enrolled. Mean AFP level of cord blood samples was 67.246±52,137 (105-226,000) ng/ml. Serum AFP levels of all 94 babies had a significant negative correlation with the postnatal age (r=-0.877, p<0.001). Results of regression analyses did not support a significant sex dependency (r= -.096, p=0.35).

Conclusion: Normal range of AFP in healthy full-term neonates and infants is very wide. Pediatric oncologists must consider moderately high values carefully in the follow-up period and if the decrease in the follow-up measurement is slower than the expected half-life for that age, the probability of an AFP-producing tumor could be high. This approach would prevent unnecessary interventions depending on false positive AFP results.