Serum prostate-specific antigen measured in children from birth to age 18 years.

We measured prostate-specific antigen (PSA) in serum from 94 cord- blood samples, from 44 newborns, and from 330 children up to age 18 years, using a highly sensitive "third generation" PSA assay on the IMMULITE (Diagnostic Products Corp.) analyzer. The serum was that remaining after cross-matching for blood transfusion. Most children were hospitalized for special care or surgery. We found detectable concentrations of PSA (> or = 0.003 micrograms/L) in many cord sera and in sera from both male and female neonates. PSA was more frequently detectable in cord and newborn sera from males than from females, but there was considerable overlap in values between the sexes, negating any possible usefulness of PSA for assigning male gender to newborns with ambiguous genitalia. PSA decreased to undetectable concentrations in most prepubertal males and females but became detectable around the age of puberty in males. We speculate that the presence of detectable PSA in cord and newborn sera results from androgenic stimulation of prostatic tissue in males or from stimulation of breast or other tissue by prolactin or progesterone in females.