Radioimmunoassay of Melatonin: Human Serum and Cerebrospinal Fluid

Abstract
Using a newly characterized anti-melatonin serum it was possible to establish human serum concentrations at short time intervals during 24 h. A clear circadian rhythm with peak values during the dark phase was demonstrated in both men and women. Values (pg/ml; mean .+-. SE) were females 02.00 h: 130 .+-. 7, 18.00 h: 45 .+-. 5; males 02.00 h: 140 .+-. 11, 18,00 h: 70 .+-. 5. The estimation (pg/ml; mean .+-. SE) of melatonin in human serum (males: 63 .+-. 22 and females: 100 .+-. 45) and CSF simultaneously taken showed that melatonin is lower in CSF (males: 59 .+-. 33 and females: 57 .+-. 28). Blanks are not subtracted.