THE PITUITARY-THYROID AXIS IN KLINEFELTER's SYNDROME

Smals, A. G. H.; Kloppenborg, P. W. C.; Lequin, R. L.; Beex, L.V.A.M.; Ross, Alec; Benraad, Th. J.

doi:10.1530/acta.0.0840072

Cited by 36 publications

(14 citation statements)

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“…In fact, when serum testosterone levels dropped to minimal val ues TSH secretion remained unchanged. These data are in keeping with those studies in which testosterone administration was un able to affect TSH secretion in patients with Klinefelter's syndrome [2], Conversely, there are also some reports in which, after testos terone administration to hypogonadal men, an increased [14] or blunted [11] pituitary response to TRH was observed. These dis crepancies may depend on different doses and pharmacological types of testosterone employed or on pretreatment testicular func tion of studied patients.…”

Section: Discussionsupporting

confidence: 90%

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Suppression of Testicular Androgenesis by <i>D</i>-Tryptophan-6-Luteinizing Hormone-Releasing Hormone Does Not Affect TSH Secretion in Male Subjects

Barreca¹,

Martorana

Franceschini³

et al. 1986

Horm Res

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Basal and TRH-stimulated TSH secretion was evaluated in six patients suffering from prostatic cancer, before and after antiandrogenic treatment performed using a long-acting LHRH analogue, D-Trp-6-LHRH. Although serum testosterone values dropped to minimal levels after treatment, TSH secretion remained unchanged. Observed results suggest that pharmacological castration does not affect the regulatory mechanisms involved in the control of TSH secretion.

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Section: Discussionsupporting

confidence: 90%

“…In fact, the lower TSH response to TRH in males can be ascribed either to low serum estrogen levels [5] or to high serum androgen levels [11]. Testosterone adminis tration inconsistently induces changes in the pituitary TSH response to TRH stimulation in hypogonadal male patients [2,11,14].…”

Section: Introductionmentioning

confidence: 99%

Suppression of Testicular Androgenesis by <i>D</i>-Tryptophan-6-Luteinizing Hormone-Releasing Hormone Does Not Affect TSH Secretion in Male Subjects

Barreca¹,

Martorana

Franceschini³

et al. 1986

Horm Res

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show abstract

“…This suppression was greater after fluoxymesterone than mesterolone. Similar observations have been made by previous authors (Cheikh et al 1975;Morley et al 1981), although this is not a uniform finding and others have reported no change in the TSH profile (Burman et al 1975), or even a slight but non significant increase in the TSH response to TRH (Smals et al 1977). The latter results could be accounted for by aromatization of testosterone to estradiol.…”

Section: Discussionsupporting

confidence: 88%

“…Increases in testosterone binding globulin (TeBG) have also been documented (Leroith et al 1981c). Several groups have assessed the effect of exogenous testosterone on PRL and TSH secretion in these patients (Burman, Dimond, Noel, Earll, Frantz and Wartofsky 1975;Cheikh, Hamilton, Hsu and Wiswell 1975;Smals, Kloppenborg, Lequin, Beex, Ross and Benraad 1977). In view of the fact that testosterone can be aromatized to estradiol or reduced to dihydrotestosterone (Nolin, Campbell, Nansel and Bogdanove 1977), the interpretation of these results is difficult because it is not possible to conclude which hormone is producing the effect.…”

Section: Introductionmentioning

confidence: 99%

Effect of Non Aromatizable Androgens on LHRH and TRH Responses in Primary Testicular Failure

Im¹,

Ej²,

Yeger³

et al. 1984

Horm Metab Res

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We have assessed the gonadotropin, TSH and PRL responses to the non aromatizable androgens, mesterolone and fluoxymestrone, in 27 patients with primary testicular failure. All patients were given a bolus of LHRH (100 micrograms) and TRH (200 micrograms) at zero time. Nine subjects received a further bolus of TRH at 30 mins. The latter were then given mesterolone 150 mg daily for 6 weeks. The remaining subjects received fluoxymesterone 5 mg daily for 4 weeks and 10 mg daily for 2 weeks. On the last day of the androgen administration, the subjects were re-challenged with LHRH and TRH according to the identical protocol. When compared to controls, the patients had normal circulating levels of testosterone, estradiol, PRL and thyroid hormones. However, basal LH, FSH and TSH levels, as well as gonadotropin responses to LHRH and TSH and PRL responses to TRH, were increased. Mesterolone administration produced no changes in steroids, thyroid hormones, gonadotropins nor PRL. There was, however, a reduction in the integrated and incremental TSH secretion after TRH. Fluoxymesterone administration was accompanied by a reduction in thyroid binding globulin (with associated decreases in T3 and increases in T3 resin uptake). The free T4 index was unaltered, which implies that thyroid function was unchanged. In addition, during fluoxymesterone administration, there was a reduction in testosterone, gonadotropins and LH response to LHRH. Basal TSH did not vary, but there was a reduction in the peak and integrated TSH response to TRH. PRL levels were unaltered during fluoxymesterone treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

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“…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].…”

Section: Discussionmentioning

confidence: 71%

Circannual Variations of Plasma Thyrotropin in Klinefelter’s Syndrome

et al. 1986

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The aim of this study was to explore the occurrence of abnormalities in the circannual thyrotropin (TSH) rhythm in Klinefelter’s syndrome (KS). For 3 years, 69 healthy adult males and 73 patients with KS, usually living in Sardinia, were studied by a cross-sectional design. Plasma samples were taken between 08.00 and 09.00 h and TSH was radioimmunoassayed. First, the mean (± SD) of the data, grouped for each month of the year, was estimated to seek any macroscopic annual variation. Then, a cosine function was fitted to the single serially independent data by the single cosinor method in order to test for any statistically significant rhythm and, if the no-rhythm assumption is rejected, to describe the circannual parameters. Our patients showed circannual mean TSH concentrations lower than controls (p < 0.001) without any statistically significant circannual rhythm, which was instead apparent in normal subjects with the annual crest time in December (95% CL November–February). Our results support the hypothesis that in KS the impaired TSH secretion may be related to abnormalities in the hypothalamic-pituitary coordination of the circannual rhythmicity of this hormone.

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THE PITUITARY-THYROID AXIS IN KLINEFELTER's SYNDROME

Cited by 36 publications

References 0 publications

Suppression of Testicular Androgenesis by <i>D</i>-Tryptophan-6-Luteinizing Hormone-Releasing Hormone Does Not Affect TSH Secretion in Male Subjects

Suppression of Testicular Androgenesis by <i>D</i>-Tryptophan-6-Luteinizing Hormone-Releasing Hormone Does Not Affect TSH Secretion in Male Subjects

Effect of Non Aromatizable Androgens on LHRH and TRH Responses in Primary Testicular Failure

Circannual Variations of Plasma Thyrotropin in Klinefelter’s Syndrome

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