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Morning urinary assessment of nocturnal melatonin secretion in older women
Author(s) -
Cook Mary R.,
Graham Charles,
Kavet Robert,
Stevens Richard G.,
Davis Scott,
Kheifets Leeka
Publication year - 2000
Publication title -
journal of pineal research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.881
H-Index - 131
eISSN - 1600-079X
pISSN - 0742-3098
DOI - 10.1034/j.1600-079x.2000.280106.x
Subject(s) - melatonin , morning , urine , endocrinology , medicine , nocturnal , testosterone (patch) , circadian rhythm , physiology
We evaluated the feasibility of using morning urine samples in epidemiological studies aimed at clarifying the relationship between nocturnal melatonin levels and breast cancer risk. Initially, a laboratory‐based study of 29 women (40–70 yr old) was performed to examine the correlation between plasma melatonin levels in hourly nocturnal blood samples and both melatonin and its major enzymatic metabolite, 6‐hydroxymelatonin‐sulfate (6‐OHMS) in morning urine samples. In a companion field study, morning urine samples were collected from 203 healthy women to assess similarities and differences in laboratory versus field measures. Taken together, our results indicate: 1) levels of melatonin and of creatinine‐corrected 6‐OHMS in the first morning void urine are strongly correlated with total nocturnal plasma melatonin output ( P <0.001) and also with peak nocturnal melatonin values ( P <0.001); 2) similar ranges for 6‐OHMS were found in the laboratory and the field; and 3) neither menopausal status nor hormonal replacement therapy altered 6‐OHMS values in morning void urine. The inclusion of morning urine samples in epidemiological studies of cancer could allow cost‐effective, widespread testing of the role played by melatonin in human health and disease.