Melatonin Plasma Levels and Circadiam Rhythms in Children

Abstract

Melatonin, the best-known pineal hormone can be determined by RIA for fewer than 5 years. There are scanty data in children only, though this age group may be of greatest interest because of speculated connections between the pineal organ and puberty. A specific plasma melatonin RIA (Stockholm antibody) was used following extraction with methylene chloride (67 %). The antigen-antibody complex was precipitated with ammonium sulfate. Intra- and inter-assay-variations were 8.9 and 11.2 %, respectively. 60 children (28 female and 32 male) with a mean age of 10 years (range: 0.8 - 18.3) had low plasma melatonin levels at day time (x = 13.0, range = 0 - 33, SD = 9.3 ng/1). At night time (0.00 - 4.00 h) melatonin increased significantly (p < 0.01) up to 200 ng/1 (x = 130). There were no sex differences. 24 hour variations were seen when melatonin was determined every two hours in pathologic conditions: dexamethasone seems to suppress peak levels in the night in Cushing-syndrome and CAH. In a 2 months old child with seizures melatonin was decreased as well as in a boy treated with ACTH because of Lennoxsyndrome, a girl with craniopharyngeoma, and a patient with pinealoma. 3 girls suffering from precocious puberty showed circadian melatonin rhythms with high night peak levels. This study was supported by DFG, SFB 34 Endocrinology