Hypothyroidism - new aspects of an old disease.

Hypothyroidism is divided in primary, caused by failure of thyroid function and secondary (central) due to the failure of adequate thyroid-stimulating hormone (TSH) secretion from the pituitary gland or thyrotrophin-releasing hormone (TRH) from the hypothalamus. Secondary hypothyroidism can be differentiated in pituitary and hypothalamic by the use of TRH test. In some cases, failure of hormone action in peripheral tissues can be recognized. Primary hypothyroidism may be clinical, where free T(4) (FT(4)) is decreased and TSH is increased or subclinical where FT(4) is normal and TSH is increased. In secondary hypothyroidism FT(4) is decreased and TSH is normal or decreased. Primary hypothyroidism is most commonly caused by chronic autoimmune thyroiditis, less common causes being radioiodine treatment and thyroidectomy. Salt iodination, which is performed routinely in many countries, may increase the incidence of overt hypothyroidism. The incidence of clinical hypothyroidism is 0.5-1.9% in women and <1% in men and of subclinical 3-13.6% in women and 0.7-5.7% in men. It is important to differentiate between clinical and subclinical hypothyroidism as in clinical symptoms are serious, even coma may occur, while in subclinical symptoms are less and may even be absent. Subclinical hypothyroidism may be transformed to clinical and as recent research has shown it may have various consequences, such as hyperlipidemia and increased risk for the development of cardiovascular disease, even heart failure, somatic and neuromuscular symptoms, reproductive and other consequences. The administration of novel tyrosine kinase inhibitors for the treatment of neoplastic diseases may induce hypothyroidism. Hypothyroidism is treated by the administration of thyroxine and the prognosis is excellent.

Thyroid function in postmenopausal women with breast cancer on tamoxifen.

In 42 postmenopausal women with breast cancer, aged 48-85 years (mean age 62.4 years) serum thyroid hormone concentrations were measured before and after 6 months of tamoxifen therapy (20 mg daily). In particular triiodothyronine (T3), thyroxine (T4), free triiodothyronine (FT3), free thyroxine (FT4), thyroxine-binding globulin (TBG) and thyroid-stimulating hormone (TSH) concentrations before and 30 minutes after thyrotrophin-releasing hormone (TRH) administration (200 microg i.v.) were measured before and 6 months after tamoxifen therapy. T3 and T4 concentrations increased significantly (p<0.001 and p<0.05, respectively) whereas FT3 and FT4 remained unchanged (p>0.05), TBG increased significantly (p<0.001) and basal TSH concentrations as well as TSH response to TRH injection increased significantly (p<0.05) after tamoxifen therapy. It is concluded that tamoxifen administration changes thyroid hormone concentrations. However free thyroid hormone levels remain unchanged and the patients remain euthyroid after long-term tamoxifen therapy.

Sex hormones in postmenopausal women with breast cancer on tamoxifen.

In 42 postmenopausal women with breast cancer aged 48-85 (mean age 62.4) years, the blood sex hormone levels were measured before and after 6 months of tamoxifen administration (20 mg daily). Follicle-stimulating hormone and luteinizing hormone levels decreased after tamoxifen administration (p < 0.001), but remained in the postmenopausal range, oestradiol levels increased (p < 0.05), sex hormone binding globulin levels increased (p < 0.001), testosterone levels remained stable (p > 0.1), free testosterone levels decreased (p < 0.001), delta4-androstenedione, 17-hydroxyprogesterone, and dehydroepiandrosterone sulfate levels remained unchanged (p > 0.1), and basal prolactin levels and their response to thyrotrophin-releasing hormone injection decreased significantly (p < 0.001) after tamoxifen therapy. It is concluded that tamoxifen has many and diverse effects on sex hormone levels, and its adverse effects do not affect the biological status of the patient, except perhaps for oestradiol, that increases in some cases, whose possible effect must be studied.

Paratesticular tumours in a patient with Nelson's syndrome.

An extremely rare case of a 39-year-old man with Nelson's syndrome and paratesticular tumours is presented. The patient had undergone bilateral adrenalectomy at the age 23 years for Cushing's syndrome. Later he developed skin and mucosal hyperpigmentation. Nelson's syndrome was diagnosed, and he underwent transfrontal hypophysectomy. At age 29, the presence of paratesticular tumours was noted which were excised together with the left testis. The preoperative levels of testosterone, produced by the paratesticular tumours, were extremely high; they fell after surgery.

Bone mineral content of junior competitive weightlifters.

It is suggested that practicing various sports can increase the bone mineral content (BMC). However, we were unable to find any reports indicating BMC changes in weightlifting, a sport which involves both extremities and spine and increases muscle mass as well. Therefore, we thought that it might be of interest to measure BMC in junior competitive weightlifters. On the occasion of a recent Junior World Championship we measured, by single photon absorptiometry, BMC in 59 young competitive male athletes (aged 15 to 20 years) from 14 countries. Several variables were taken into account for each subject, including race, record, age, height and weight. Multiple regression analysis was performed in order to assess the contribution of the above mentioned variables to the variability of both distal and proximal BMC. Finally, athletes' BMCs were compared to matched sex and age normals. Our results suggest that junior competitive weightlifters have an increased BMC, well above the age-matched controls' mean. It seems that the vigorous exercise of weightlifters tends to fade out any race or age-related BMC differences. Finally, weightlifters' BMC seems to be highly correlated with body weight and record.

Bone mineral loss related to menstrual history.

We measured the bone mineral content (BMC) of the forearm in 173 normal postmenopausal women. We also examined the relation between BMC and the chronologic age, the number of years elapsed since menopause, and the total number of menstrual cycles during the reproductive years. BMC had a better linear relation to the total number of menstrual cycles than with the years elapsed since menopause or with chronologic age.