G. Galvanini

Substrate-product relation of 1-hydroxylase activity in primary hyperparathyroidism.

The synthesis of the active form of vitamin D, 1,25-dihydroxyvitamin D (1,25-(OH)2D), is thought to be relatively insensitive to the serum concentration of its precursor, 25-hydroxyvitamin D (25-OH-D). We compared the effect of oral administration of 25-OH-D3 (50 micrograms per day for one month) on serum concentrations of calcium, phosphate, parathyroid hormone, 25-OH-D, and 1,25-(OH)2D in five healthy adults and in six patients with primary hyperparathyroidism. In normal adults the mean (+/- S.D.) serum level of 25-OH-D rose from 18 +/- 9 to 136 +/- 47 ng per milliliter; no significant changes were observed in the other serum levels. In contrast, comparable increases in the levels of circulating 25-OH-D in patients with primary hyperparathyroidism caused a consistent slight rise in serum calcium and phosphate levels, a partial suppression of parathyroid hormone, and a sharp increase in the level of 1,25-(OH)2D. During this period a significant positive correlation was found between serum concentrations of 25-OH-D and 1,25-(OH)2D (P less than 0.001). These results provide evidence that in patients with primary hyperparathyroidism, levels of circulating 1,25-(OH)2D may be more dependent on the prevailing serum concentrations of 25-OH-D than they are in normal adults.

Suppressive effect of chronic glucocorticoid treatment on circulating calcitonin in man.

INTRODUCTION Many factors contribute to glucocorticoid-in deced osteopenia.Corticosteroid excess leads to in testinal malabsorption of calcium through a direct inhibition of the intestinal absorptive process(l, 2) or through an impaired vitamin D metabolism (3, 4). A direct action of the corticosteroid on bone tissue has also suggested (5). On the other hand an impaired calcitonin (CT) secretion has been suggested to be a factor in the pathogenesis of some forms of decreased bone mass (6,7) . To explore a possible relationship between CT secretion and steroid induced bone loss we studied the secretion of this hormone before and during long term treatment with eorticosteroids.

Somatostatin inhibition of insulin secretion in insulin-producing tumors.

Abstract Synthetic linear somatostatin infused in two patients with insulin producing tumors lowered slightly basal insulin and a little less basal glucose levels; above all it inhibited insulin release induced by glucose, glucagon, and tolbutamide.

Discriminant analysis in the differential diagnosis of hypercalcaemia.

Linear discriminant analysis, a multivariate statistical procedure, applied to serum calcium, phosphate, alkaline phosphatase, bicarbonate, chloride, creatinine and tubular reabsorption of phosphate, proved to be effective in distinguishing patients with Primary Hyperparathyroidism from other hypercalcaemic patients in eighty‐four retrospective cases. The application of the model to thirty‐four prospective cases enabled us to separate correctly, hyperparathyroid patients from non‐parathyroid hypercalcaemic patients.

Response of Paget’s disease to human calcitonin in patients resistant to porcine calcitonin

Eleven patients with Paget’s disease of bone, treated intermittently for 2–4 years with porcine calcitonin (pCT) and clinically resistant to pCT [no modifications of serum alkaline phosphatase (ALP) and urinary hydroxyproline (uHOP) during pCT administration] were treated with 0.5–0.25 mg/day of human calcitonin (hCT) for 3–6 months. Nine of our patients showed biochemical improvement during the first 2 months of treatment, with reduction in ALP and uHOP. In one patient with slightly increased ALP and uHOP, and in another one during the second treatment course, hCT treatment did not modify the biochemical indices of bone disease. However all patients, including those with biochemical resistance, experienced a remarkable diminution of bone pain, which had not been observed during previous pCT treatment courses. Therefore, hCT appears to be indicated for therapeutic use in patients who are resistant to foreign calcitonins.

Serum thyroid hormone concentrations and weight loss relationships in eight obese women during semistarvation.

Eight obese female patients were studied over a period of 15 days whilst on 300 kcal diet. Serum levels of thyroxine and free thyroxine index were not altered significantly by semistarvation. A TRH test performed before and after the diet showed no appreciable change. Weight loss was initially rapid but later slowed despite good patients compliance. Serum concentrations of T3 and reverse T3 (rT3) early decreased (p<0.01) and increased (p<0.05) respectively, but returned towards control levels even before discontinuation of semistarvation. There was a positive correlation between the percentage decrease in body weight and the percentage increase in serum rT3 (p<0.001), and a negative correlation between decrease in body weight and decrease in serum T3 (p<0.001). Our results do not suggest that the variations in serum triiodothyronines limit the weight loss; it is probable, on the contrary, that the weight loss promotes the observed variations in thyroid hormones by as yet unknown adaptive metabolic forces.

Calcium and parathyroid hormone behaviour after exogenous secretin infusion in man.

The response of serum calcium, PTH, CT and gastrin to an infusion of secretin (3 CU/kg/h) over a period of 90 min was studied in ten healthy males and two female patients with hypoparathyroidism.

FAILURE OF SOMATOSTATIN TO DIAGNOSE ORGANIC HYPERINSULINISM

SUMMARY. In four patients with organic hyperinsulinism (two with surgically proven β‐cell adenomas of the body of the pancreas) a standard tolbutamide test during continuous somatostatin infusion (5 μg/min) was carried out. Tolbutamide‐induced insulin release was completely inhibited by somatostatin as in normal subjects. These results suggest that the inhibition test with somatostatin does not seem to be a better or safer way of diagnosing insulin producing tumours.

Diagnostic value of urinary cyclic AMP measurement in patients with calcium nephrolithiasis.

One hundred patients with recurrent calcium nephrolithiasis were submitted to the Pak test. At fasting state hypercalciuria was found in 27 cases, while a group of 16 further patients became hypercalciuric after oral calcium load. Only measurement of urinary cAMP excretion in both conditions made it possible to diagnose renal hypercalciuria in 9 out of 27 patients in the former group; according to test results 4 patients were expected to have primary hyperparathyroidism, but afterwards the disease was identified in only one case.