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dc.contributor.authorPrinz, Patricia N.en_US
dc.contributor.authorBremner, William J.en_US
dc.contributor.authorVitiello, Michael V.en_US
dc.date.accessioned2008-10-17T20:41:08Z
dc.date.available2008-10-17T20:41:08Z
dc.date.issued1983-06en_US
dc.identifier.citationJ Clin Endocrinol Metab. 1983 Jun;56(6):1278-81en_US
dc.identifier.urihttp://hdl.handle.net/1773/4335
dc.description.abstractPrevious studies concerning the relationship of serum testosterone levels to aging in normal men have yielded apparently inconsistent results. Studies performing blood sampling in the morning have often shown an age-related decrease in testosterone levels, while those using afternoon samples have failed to show such a decrease. These results suggested to us the possibility that the circadian rhythm in serum testosterone levels might be altered with normal aging in men. Hourly blood samples were obtained for 24 h from 1 young (mean age, 52.2 yr) and 12 old (mean age, 17 yr) healthy men. Total testosterone levels were measured by RIA. The circadian rhythm in serum testosterone levels found in normal young men was markedly attenuated or absent in healthy elderly men; the early morning rise in testosterone levels characteristic of young men was not present in old age. Mean testosterone levels for the entire 24-h day were lower in healthy old men than in young men. These results demonstrate a clear decrease in serum testosterone levels in healthy old men compared to those in young men and provide an explanation for the inability to demonstrate an age-related decline in testosterone levels in earlier studies using serum samples obtained in the afternoon.en_US
dc.language.isoen_USen_US
dc.publisherEndocrine Societyen_US
dc.subjectandrologyen_US
dc.subject5-alpha reductase inhibitorsen_US
dc.subjectgonadotropinsen_US
dc.subjectklinefelter's syndromeen_US
dc.subjecttestosteroneen_US
dc.subjectreifenstein's syndromeen_US
dc.subjectmale contraceptionen_US
dc.subjectspermatogenesisen_US
dc.subjectcolchicineen_US
dc.subject.meshHumansen_US
dc.subject.meshComparative Studyen_US
dc.subject.meshMiddle Ageden_US
dc.subject.meshResearch Support, U.S. Gov't, P.H.S.en_US
dc.subject.meshMaleen_US
dc.subject.meshAdulten_US
dc.subject.meshTestosterone, blooden_US
dc.subject.meshResearch Support, U.S. Gov't, Non-P.H.S.en_US
dc.subject.meshAgingen_US
dc.subject.meshCircadian Rhythmen_US
dc.subject.meshAgeden_US
dc.titleLoss of circadian rhythmicity in blood testosterone levels with aging in normal menen_US
dc.typeArticleen_US


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