The Effect of High Parathyroid Hormone Concentration on Calcitonin in Patients with Primary Hyperparathyroidism²)

Abstract

Serum calcitonin (CT), parathyroid hormone (PTH), and calcium levels were measured in 23 patients with primary hyperparathyroidism. PTH was determined by a midregion (M-RIA) and a carboxyl-terminal (C-RIA) specific PTH-RIA. Only 2 patients had elevated CT levels. In contrast to the findings in 46 healthy controls, the CT levels did not correlate with calcium levels. Patients who had the highest iPTH values showed a negative correlation between CT and iPTH (M-RIA (n = 7): R = -1.0000, p less than 0.001; C-RIA (n = 13): R = -0.5604, p less than 0.05). The results of the C-RIA were subtracted from those of the M-RIA. In 12 patients with the highest levels of intact PTH (M-RIA - C-RIA), serum PTH concentration was inversely correlated with serum CT concentration (R = -0.7343, p less than 0.01). In the same patients a negative correlation between CT and calcium was found (R = -0.6783, p less than 0.02). These findings suggest that high PTH levels may have a direct suppressive effect on CT concentration and this may be, at least in part, responsible for failure of CT concentrations to rise in many patients with primary hyperparathyroidism.

Could Primary Hyperparathyroidism-Related Hypercalcemia Induce Hypercalcitoninemia?

“…The relationship between CT and hypercalcemia revealed some discrepancies: if an acute increase of serum calcium was clearly demonstrated to stimulate CT secretion, the effect of chronic hypercalcemia on CT secretion remains unclear [2,6,7,8,9,10,11,12]. …”

“…Although most of the authors found normal CT levels [7,8], others have reported basal elevated CT: in about 50% of cases in a series of 28 patients, and in men only from another series of 55 patients [9,10,11]. However, all these studies were done in a small series of patients and used polyclonal CT radioimmunoassays which are not specific of the mature CT monomer, which should explain the reported high CT levels in these series.…”

“…Acute hypercalcemia was shown to increase CT secretion by thyroid C cells, depending on both the calcium concentration and the level of calcium increase, which supports the use of calcium infusion as a stimulating CT secretion test [3,4,5]. On the contrary, the effect of chronic hypercalcemia on CT secretion remained debated: some studies found an increased CT secretion while others did not [6,7,8,9,10,11,12]. However, all these reports were done in small series of patients and have not been reconsidered by using current immunometric CT assays [6,7,8,9,10,11,12].…”

Optimizing the dynamics of bone turnover with genetic algorithm

“…According to Kübler et al. ( 1987 ), the production of CT from the thyroid gland is stimulated by an increase in the number of active “Osteoclasts”, while an increase in the amount of parathyroid hormone (“Para-thyroid hormone”) decreases the secretion of CT. This process is modeled by the term and natural degradation of CT is modeled by .…”