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We assessed the 24-h behavior of circulating TSH and the dopaminergic control on TSH release in a postmenopausal woman, who had elevated levels of serum thyroid hormones and an inappropriately high concentration of serum TSH, indicating pituitary resistance to thyroid hormone action. The patient was found to have a daily profile of serum TSH similar to that of normal subjects, except for the persistently elevated 24 h levels, suggesting that alterations in thyroid hormone negative feedback control did not affect substantially circadian TSH rhythm. The acute administration of a dopamine antagonist drug (metoclopramide) resulted in a markedly elevated peak of serum TSH, similar both in the morning and in the evening. The chronic administration of a dopamine agonist drug (bromocriptine) reduced basal and TRH-stimulated TSH, restored circadian TSH variations to lower levels, and normalized other thyroid function tests. Although the metoclopramide test results confirmed the existence of an increased dopaminergic inhibitory tone in nonneoplastic inappropriate secretion of TSH, the outcome of bromocriptine treatment indicated that the dopaminergic control over TSH release was not enough in this case of PRTH.

The effects of a TRH-T (protireline tartrate) treatment at a dose of 2 mg/day for 3 weeks on the serum levels of the pituitary-thyroid axis hormones, have been studied in a randomized group of 10 elderly euthyroid hospitalized patients with cerebrovascular disease. At the end of the treatment an 8.3% mean increase of serum T3 level and a 12.5% mean increase of serum FT3 level (p less than 0.02 in both cases) have been observed. At the same time a 34% mean decrease of the basal TSH (p less than 0.05) and a 26% mean decrease of the delta-TSH after TRH-test (p less than 0.025) have been noted. However, the hormone concentrations changes never exceeded the normal values. In a randomized group of 9 hospitalized untreated patients with cerebrovascular disease used as controls (matched for age and sex), no significant changes of studied hormones have been recorded. In the treated patients, one week after the withdrawal of therapy serum levels of thyroid hormones and TSH went back to the levels observed before treatment. TRH-T seems to cause these modest hormone changes by decreasing the number of TRH receptors and the activity of TSH secreting cells. Nevertheless, the presence of the normal feedback in the pituitary-thyroid axis, allows a good tolerance to such a treatment.

Thyroid hormone picture of 28 patients (15 males and 13 females), mean age 56.6 yr (range 45-65 yr), with seriously decompensated type II diabetes mellitus has been studied. In each patient the study was repeated after 3 months of treatment of diabetes. The patients showed significantly lower serum T3 levels and significantly higher serum rT3 levels (P less than 0.001), in comparison with a group of 16 normoglicemic subjects. After 3 months of strict control of diabetes T3 and FT3 significantly increased (P less than 0.01), whereas significant variations of rT3 were not found. Among the whole group of diabetics 5 patients had low levels of serum T4 (P less than 0.01 vs. controls), high levels of serum TSH (P less than 0.001 vs. controls) and an exaggerated responsiveness to exogenous TRH (P less than 0.001 vs. controls). After the 3 months of treatment these patients showed a significant decrease of rT3 (P less than 0.02) and of delta-TSH (P less than 0.01). In the whole group of diabetics significant statistical correlations between glycometabolic and thyroid parameters were not found. The study, on the whole, showed in patients with seriously decompensated type II diabetes, a hormone picture like the low-T3 syndrome, in some cases, however, pituitary TSH secretion suggested the existence of incipient failure of thyroid hormones. A connection between alterations in thyroid hormone picture and glycometabolic imbalance, even statistically labile, is however indicated by improvement of thyroid function when diabetes is carefully controlled.

This work was performed in order to analyze thyroid hormone picture of alcoholic patients with reference to hepatic damage. Forty consecutive patients of male sex, aged 28-64 years, were investigated. They consumed more of 50 g ethanol/day for at least 2 years. According to investigations on hepatic condition, 2 cases had normal liver, 22 cases had steatosis and 16 had cirrhosis. None of patients disclosed a clinical and/or hormonal behaviour pointing to alterations of thyroid function. In alcoholics serum T3 levels resulted significantly lower compared to a control group of 40 healthy males (P less than 0.001), independently of degree of hepatic damage. Instead, serum T4 levels did not result significantly different in the comparison between alcoholics and controls. Serum FT3 and FT4 levels resulted significantly higher (P less than 0.001) only in alcoholics with liver cirrhosis. In comparison with normals, serum rT3 was significantly lower in alcoholics without liver cirrhosis (P less than 0.001), but significantly higher in alcoholics with liver cirrhosis (P less than 0.005). Serum TBG behaved in the same manner. According to euthyroidism in our alcoholic patients basal and TRH-stimulated TSH were normal, however significantly lower when compared to controls (P less than 0.005). On the whole these results suggest the existence of an autonomous ethanol-dependent mechanism that determine decreased serum T3 levels in the alcoholics, in absence of serum T4 variations. In the alcoholic with liver cirrhosis, an increased conversion of T4 in rT3, correlated to hepatic damage, joins to previous mechanism. The tendency to low secretion of pituitary TSH might be dependent of action of alcohol on neuromodulation of TRH secretion.

We have attempted to determine if mild hyperglucagonemia induced by exogenous glucagon infusion induces changes of serum thyroid hormone levels. Eleven healthy subjects, overnight fasting, received glucagon infusion (2 mg/90 min i.v.), whereas 5 healthy subjects (control group) received normal saline infusion. In the subjects infused with exogenous glucagon plasma glucagon concentrations increased from 130 +/- 24 pg/ml to 550 +/- 68 pg/ml at the end of infusion. At the same time no significant changes in serum T3, rT3 and T4 levels were found. A significant increase in serum rT3 levels was found 270 min after glucagon infusion withdrawal, whereas serum T4 levels remained unaltered during the whole period. Normal saline infusion failed to induce any variation in control group, however a late (at 6th hour) mild increase of serum rT3 in these subjects resulted comparable to the same increase of glucagon infused subjects. The results from this study suggest that mild increase in plasma glucagonemia, as found in patients with severe illness, does not induce a short-time significant lowering of serum T3 and a simultaneous rise of serum rT3 in normal subjects.

The aim of the present study was to determine whether the temporary variations in blood thyroid hormone levels secondary to a therapeutic dose administration of L-thyroxine observed in adequately treated hypothyroid patients also occur in spontaneously euthyroid subjects under analogous conditions. Serum levels of T3, T4, FT3, FT4 and TSH were measured over 6 hours following a single oral administration of L-thyroxine (dosage 85 mcg/mq body surface area) in a group of 18 euthyroid volunteers and 8 hypothyroid patients adequately compensated with replacement therapy. In the euthyroid subjects there was a significant increase in T4 and a significant fall in TSH values at 60', while a significant decrease in FT3 and FT4 as compared to initial values was observed at 120'. In the treated hypothyroid patients serum T3 and T4 increased at 120', while FT4 concentrations, already significantly higher at 120', still remained higher than initial levels at 360'. The different behaviour of the hypothyroid patients, in spite of being compensated with therapeutic doses of L-thyroxine, reflects the persistence of a thyroid-metabolic condition substantially different to the physiological feature, which appears to be realized by means of a reduced iodothyronine clearance and a lower sensitivity in TSH feedback.