Normative melatonin excretion: a multinational study

The present study on overnight urinary melatonin was conducted on the most geographically dispersed population to date, over a 1 year period, also cov ering a broad age range (18-62 years). An inverse relationship between mela tonin and age, as well as between melatonin and weight was observed for bot h genders. Females as a whole, had higher melatonin values than males. Furt hermore, the excretion of melatonin exhibited a bimodal distribution, disti nguishing two groups of individuals: low and high melatonin excretors, The cut-off point was set at 0.25 nmol/l for ages up to 40 years and at 0.20 nm ol/l for subjects above this age, Since melatonin may be involved in severa l physiological and pathological processes, it could be of importance to de tect the type of melatonin excretion that prevails in various conditions, u sing a simple noninvasive procedure such as the overnight urinary measureme nt. For that purpose, this large sample could serve as a worldwide referenc e databank across different ages and locations. (C) 1999 Elsevier Science L td. All rights reserved.