Increased gonadotropin levels in newborn premature females treated by phototherapy

A group of 16 premature infants (9 females and 7 males) who were treated with phototherapy because of jaundice were compared in respect of plasma gonadotropin levels to a control group of 10 premature infants (4 girls and 6 boys) who did not require phototherapy. Luteinizing hormone (LH) and follicle stimulating hormone (FSH) were measured by radioimmunoassay. During the third and fourth week of life, gonadotropins increased simultaneously in phototherapy treated females (FSH P < 0.001; LH P < 0.01), reached high values (20 and 80 mU/ml, respectively), stayed elevated during three weeks, then declined quickly to under 10 mU/ml. In the group of treated males no significant rise in FSH and LH was observed. Constant phototherapy and/or the sudden stopping of this treatment in the jaundiced premature newborn female is responsible for a marked and transient elevation of gonadotropins.