Calcitonin reserve and the differentiated response to calcitonin in osteoporosis.

The authors followed up the effect of calcium and calcitonin administration on phosphorus-calcium balance and on calcium retention, in correlation with the level of endogenous calcitonin, in 20 patients of perimenopause age (40-50 years), with radiologically confirmed osteoporosis. Calcium retention after loading with calcium gluconate (180 mg in i.v. injections) was determined before and after administration of salmon calcitonin (100 IV in i.m. injections). Two types of responses were noted. In a group of patients calcitonin administration determined a rise of calcium retention at the same time with the improvement of other biochemical parameters as well as a normal calcitonin response. The presence of high levels of circulating calcitonin 24h after loading with exogenous calcitonin demonstrated a slower inactivation rate of the hormone in these patients. The other group showed no positive response to calcitonin. The proposed test is a criterion for the selection of the patients with osteoporosis in view of chronic calcitonin treatment.

Parathormone and calcitonin secretion in endemic goiter.

The investigations performed on 160 females of adult age with goiter and clinical signs of spasmophilia followed up the serum and urinary calcium and magnesium. The calcitonin and parathormone circulating levels were also determined. Although the levels of serum and urinary calcium and magnesium appear normal in adult subjects with simple goiter, decreased levels of the circulating parathormone were confirmed in most cases. The values of circulating calcitonin were within normal limits. The moderate hypoparathyroidism noted is an indication of the possible association of "parathyroid dystrophy" with endemic goiter.

High levels of plasma von Willebrand factor in hyperthyroidism.

Both von Willebrand factor antigen and activity tested as ristocetin cofactor, were found to be increased in the 20 patients with hyperthyroidism, while changes detected on the 10 hypothyroid patients did not significantly differ from the mean values recorded in 19 healthy control subjects. It is considered that the high levels of endothelia-derived plasma von Willebrand factor in hyperthyroidism is the result of a long-standing stimulation of vascular endothelial cells by either a direct effect of thyroid hormones or by an excessive adrenergic activity. The present findings represent an important limitation in interpreting raised levels of plasma von Willebrand factor as a marker of endothelial injury or in terms of a thrombotic tendency.

Calcitonin secretion in rats with inflammation mediated osteopenia.

The authors followed up the occurrence of inflammation-mediated osteopenia (IMO) in young and adult rats weighing 50 g and 150 g, respectively. The calcemia, the amount of bone calcium and the calcitonin content of the thyroid gland were determined. Calcium loss from bones was similar in both groups, irrespective of age. However, in the young animals a significant rise of calcitonin content of the thyroid gland was found (11.08 ng/ml as compared with 3.81 ng/ml in the controls). In adult animals with IMO the level of calcitonin in the thyroid gland showed no change as compared with the controls. Calcitonin reactive hypersecretion in the young animals was not able to prevent the development of IMO, characterized by an important loss of bone calcium.

Late hypothyroidism following subacute thyroiditis.

The authors followed up the incidence of permanent hypothyroidism in 35 patients with subacute thyroiditis (SAT) in their past history. The investigations were made one to four years after the acute episode. Ten of these presented repeated recurrences despite the therapy with glucocorticoids. The investigations included serum determination by RIA of T4, T3, TSH and thyroglobulin as well as of circulating thyroid antibodies. Permanent hypothyroidism subsequent to SAT occurred in two patients. In one of them it occurred following thyroid surgery performed for repeated recurrences. Both patients presented high levels of circulating thyroglobulin antibodies suggesting a possible transition to autoimmune thyroiditis. In the authors' opinion permanent hypothyroidism is likely to develop after SAT only in association with an autoimmune process or after thyroid surgery.

Calcitonin secretion in thyroid insufficiency.

The level of circulating calcitonin was followed up in 30 patients with severe hypothyroidism, diagnosed clinically and by laboratory examinations. Four of the patients under study had goiter. The complex investigation of phosphorus-calcium metabolism, including radioimmunoassay of calcitonin was made under basal conditions and after calcium loading. The results revealed low basal urinary calcium excretion and an increased skeletal uptake of calcium after loading. Calcitonin secretion persisted in 8 of the patients under basal conditions and it increased after calcium loading in another 14 of them, accounting for the increased "skeletal avidity" for calcium. The persistence of calcitonin secretion supports an earlier clinical observation concerning the relative integrity of the skeleton in patients with hypothyroidism. In the hypothyroid patients with goiter the results do not differ from those obtained in the remaining patients.

Cardiac arrhythmias and submaximal exercise test.

Cardiac arrhythmias, investigated in 1000 persons subjects to a submaximal exercise test, showed an incidence of 6%. The most frequent were the ventricular premature beats, related in more than half of the cases to an organic, probably ischemic, heart disease. Left bundle branch block and ventricular tachycardia were rare and indicated an organic heart disease. Several other rare arrhythmias are discussed. In patients with exercise-induced cardiac arrhythmias, an increased ratio of the tension-time index to maximal oxygen consumption indicates an uneconomical and less efficient cardiac work. The increase of the PEP and of the PEP/LEVT ratio during recovery, in the subjects exhibiting exercise-induced ventricular premature beats, also suggests a lowered cardiac efficiency. These findings support the view that cardiac arrhythmias frequently coexist with an organic, especially ischemic, heart disease.