Circannual Variations of Plasma Testosterone, Luteinizing Hormone, Follicle-Stimulating Hormone and Prolactin in Klinefelter’s Syndrome

Abstract

To clarify the influence of primary testicular failure upon circannual hormone rhythmicity we have been studying, by cross-sectional design, 93 adult patients with Klinefelter’s syndrome (KS) and 64 adult healthy males to look for evidence of circannual rhythms in testosterone (T), LH, FSH and PRL plasma concentrations. Plasma samples were taken from 08.00 to 09.00 h and all hormones were measured by radioimmunoassay. The data were assessed by the single cosinor method in order to obtain evidence for any significant rhythm and to estimate its parameters mesor, amplitude and acrophase. In the controls, annual rhythms were validated for the secretion of T (annual crest time in September), LH (annual crest time in February) and FSH (annual crest time in January), whereas PRL did not show a significant annual rhythm. In KS, significant circannual rhythms were validated for the secretion of T (annual crest time in April) and FSH (annual crest time in September), but not for LH and PRL secretion. Our results suggest that in KS the circannual hormone rhythmicity may be influenced by seminiferous tubule dysgenesis.

Circannual Variations of Plasma Thyrotropin in Klinefelter’s Syndrome

“…Our results demonstrate the occurrence of a circannual TSH rhythm in healthy men with characteris tics similar to those reported for other populations in the above mentioned papers. In KS, an impaired TSH secretion has been found and it has been referred to primary involve ment of the thyroid [3,13,18] or to an abnormality in the hypothalamic-pituitary regulation [5][6][7]16], In our patients, the annual mean of TSH values, lower than in the controls, seems to confirm a blunted TSH release in KS [6. 16].…”

“…In Klinefelter's syndrome (KS) TSH secretion has been found altered by several authors, without special stim ulation and after a TRH stimulus [4-7, 13, 16, 18]. More over, changes of circannual hormone rhythmicity have been recently found in this syndrome [3]. The aim of this study was to clarify the influence of primary gonadal fail ure upon circannual TSH rhythmicity.…”

Chrono-Endocrinology in Clinical Practice: A Journey from Pathophysiological to Therapeutic Aspects

“…Seasonal variations in these hormones are particularly important for sexuality and fertility, also in humans [97]. A circannual rhythm of pituitary and gonadal hormones, already present in the prepubertal age, is consolidated in the adults and presents a secretory acrophase of LH in January (Wintertime in North Hemisphere) in both sexes and of testosterone in late summer/autumn in men [66,97,98]. The occurrence in adult men of circannual LH and testosterone rhythms without overlapping phases but in antiphase (shift of approximately six months = 180 • ), seems to indicate that the driving role of these rhythms is played by the testis and that testosterone variations regulate by negative feed-back the pituitary infradian LH rhythm [66,99].…”

“…A circannual rhythm of pituitary and gonadal hormones, already present in the prepubertal age, is consolidated in the adults and presents a secretory acrophase of LH in January (Wintertime in North Hemisphere) in both sexes and of testosterone in late summer/autumn in men [66,97,98]. The occurrence in adult men of circannual LH and testosterone rhythms without overlapping phases but in antiphase (shift of approximately six months = 180 • ), seems to indicate that the driving role of these rhythms is played by the testis and that testosterone variations regulate by negative feed-back the pituitary infradian LH rhythm [66,99]. This seems to be confirmed by the persistence of a circannual testosterone rhythm in people with hypogonadotropic hypogonadism, and with Klinefelter's syndrome, even if at lower secretory levels and with a phase shift [97][98][99].…”

“…The occurrence in adult men of circannual LH and testosterone rhythms without overlapping phases but in antiphase (shift of approximately six months = 180 • ), seems to indicate that the driving role of these rhythms is played by the testis and that testosterone variations regulate by negative feed-back the pituitary infradian LH rhythm [66,99]. This seems to be confirmed by the persistence of a circannual testosterone rhythm in people with hypogonadotropic hypogonadism, and with Klinefelter's syndrome, even if at lower secretory levels and with a phase shift [97][98][99]. The independence of serum testosterone seasonality from infradian LH fluctuations has been confirmed by a more recent study and attributed by the authors to the changes in environmental temperature and daylight duration [100].…”