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Circadian aspects of serum prolactin and TSH lowering by bromocriptine in patients with prostatic hypertrophy
Author(s) -
Tarquini Brunetto,
Halberg Franz,
Seal Ulysses S.,
Benvenuti Maria,
Cagi Mario
Publication year - 1981
Publication title -
the prostate
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.295
H-Index - 123
eISSN - 1097-0045
pISSN - 0270-4137
DOI - 10.1002/pros.2990020305
Subject(s) - bromocriptine , endocrinology , medicine , prolactin , circadian rhythm , ultradian rhythm , infradian rhythm , morning , bedtime , evening , hormone , physics , astronomy
Bromocriptine mesylate lowers the serum concentration of prolactin and TSH in patients with prostatic hypertrophy as a function of drug administration time. The effect of a 2.5‐mg dose in lowering these two hormones in presumably similar patients is statistically highly significant and relatively large at unusual test times (in the evening); at other, conventional test or administration times (early morning or midday), it is smaller, questionable, or not demonstrable with the dose and conditions used. Dosing without timing may lead to reduced effect or lack of effect, ambiguity and controversy, and lack of timing may account for the circumstance that an effect of bromocriptine upon TSH in human serum was not previously established. Rigorous assessment of the effect of bromocriptine mesylate upon circulating TSH and prolactin requires consideration of the entire spectrum of rhythms, ultradian and infradian as well as circannual. The circadian approach here analyzed represents a step toward that goal and indicates that the circadian frequency is a critical determinant of this response. Manipulation of TSH concentration in serum, in turn, is of interest in view of the demonstrated alteration of the circannual TSH rhythm in patients with prostatic cancer.