The effect of short-term treatment with recombinant human thyroid-stimulating hormones on leydig cell function in men.
ABSTRACT High levels of thyroid-stimulating hormone (TSH) have been implicated as a cause for precocious puberty associated with severe long-standing juvenile hypothyroidism. Recombinant human thyroid-stimulating hormone (rhTSH) is available for the management of patients with thyroid carcinoma, and after its administration the serum TSH levels are similar to those observed in hypothyroid infants with precocious puberty. Our objective was to investigate whether rhTSH increased testosterone secretion in adult males with differentiated thyroid carcinoma. Thirty-one adult Caucasian men, ages 18-59 years, with differentiated thyroid carcinoma were studied. While continuing on thyroid hormone therapy, patients received 0.9 mg of rhTSH 24 hours apart. Blood samples were obtained before the first rhTSH dose (day 1) and at 24 hours (day 3) and 72 hours (day 5) after the second rhTSH dose. TSH, total testosterone, luteinizing hormone (LH) and follicle-stimulating hormone (FSH) were determined. Serum TSH levels were increased at day 3 (129.2 +/- 5.7 micro U/mL) versus day 1 (0.6 +/- 0.2 micro U/mL) but observed differences in total testosterone, LH and FSH throughout the study were not statistically significant. In conclusion, short-term elevations in serum TSH levels in the range reported in hypothyroid boys with precocious puberty did not increase serum testosterone levels in adult men.
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ABSTRACT: Nine of 15 boys with severe long-standing primary hypothyroidism were found to have macroorchidism. All 15 patients had elevated thyroid-stimulating hormone levels. However, only those patients with testicular enlargement had striking elevations of serum prolactin and gonadotropin values. The response to gonadotropin-releasing hormone in our patients was blunted, in contradistinction to that of children with true precocious puberty. In spite of the elevated levels of luteinizing hormone, the serum testosterone levels were in the prepubertal range, explaining the lack of peripheral manifestations of androgenic effect. Improvement of testosterone secretion followed decreasing prolactin levels with bromocriptine administration, suggesting an inhibitory effect of prolactin on luteinizing hormone action at the Leydig cell. We conclude that testicular enlargement is the result of continuous follicle-stimulating hormone stimulation and that the term "true precocious puberty" is not appropriate in children with hypothyroidism and macroorchidism unless the hypothalamic-pituitary gonadal axis is shown to be at the pubertal stage.Journal of Pediatrics 04/1988; 112(3):397-402. · 4.04 Impact Factor
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ABSTRACT: The role of thyroid hormones in the testis is unclear, although recent evidence indicates they may be important for testicular development. Here we describe a novel method for increasing adult testicular size in the rat by induction of transient hypothyroidism during neonatal life. Rats were treated with a reversible goitrogen, 6-propyl-2-thiouracil from birth to day 25 when treatment was stopped, allowing return to a euthyroid state. At days 90, 135, 160, and 180, wt and DNA content of the testis, epididymis, ventral prostate, seminal vesicle, and those of some nonreproductive organs were determined, as well as serum levels of testosterone (T) and thyroid hormones. Despite decreased body wts in 90-day and older 6-propyl-2-thiouracil-treated rats, testis wt was increased by 40% and 60% at 90 and 135 days, respectively; maximal increase (80%) occurred at 160 days. These wt increases were accompanied by proportional changes in DNA content. Significant enlargements were also seen in other reproductive organs, but they occurred after a time lag and were smaller in magnitude. Interestingly, serum T levels showed no increase at any age. Weight and DNA content of nonreproductive organs, like body wts, were less than controls at all ages but thyroid hormone levels were normal. Thus, transient hypothyroidism in neonatal rats is associated with lasting enlargements in the ultimate size of testis and other reproductive organs in the adult. These changes are not related to excess T levels. The results indicate early critical influences of thyroid hormones on growth and development of the reproductive system and suggest an experimental model for inducing lasting enlargements in testis and reproductive organs. The model may also be useful for studying regulation of reproductive growth and final size.Endocrinology 08/1991; 129(1):237-43. · 4.72 Impact Factor
- Biology of Reproduction 12/1978; 19(4):768-72. · 4.03 Impact Factor