NOCTURNAL THYROTROP IN SURGE IN NORMAL CHILDREN

Abstract

A nocturnal surge in serum thyrotropin ( TSH) occurs in adults between late afternoon and midnight. To determine if a similar TSH surge occurs in children, we studied 32 children, ages 4 to 18 years, who were normal in height and weight. Samples for TSH were drawn through an indwelling catheter hourly for 24 hours in older children or 1500 to 0400 in smaller children. Serum TSH was measured by a 3-site mouse monoclonal IRMA( Serono Diagnostics, Inc.), which has a sensitivity less than 0.3 μU/ml. The nocturnal TSH surge was calculated as the percent increase in the nighttime TSH (3 consecutive values with highest mean) over the daytime TSH (3 consecutive values with lowest mean). The time of peak was the mid-time point of the highest 3 values at night. Values shown are mean ± SE; * p < .001, compared with age 4-8. These data indicate that infants of Kallmann's fathers have the gonadotropin and sex steroid surge shown for normal infants. We conclude that either our infants do not have Kallmann's syndrome, or the neonatal surge remains intact despite protential later loss of gonadotropin release.