[Effects of H2 blockers on blood levels of parathormones and calcitonin in normal subjects].

It has recently been reported that cimetidine (CMT) treatment can reduce parathormone (PTH) levels and that histamine (HA) plays an important role in the physiological modulation of PTH secretion. Thus far, no correlation has been sought with calcitonin (CT) or prolactin (PRL) which are themselves capable of modifying electrolyte and mineral homeostasis. Six healthy subjects were subjected to i.v. boli with H2-blockers (4 with cimetidine (CMT) 200 mg; 2 with ranitidine (RNT) 50 mg) in order to assess their effect on serum Ca, P, CT and PTH and to verify whether the increase in PRL induced by CMT but not by RNT, correlated with PTH and CT changes. Personal data show that neither CMT nor RNT modify basal levels of Ca, P, PTH and CT; the delta % of PRL was significantly higher after CMT than after RNT but no correlation was evident between each pair of hormones. It is concluded that more information is needed about the histamine modulation of PTH secretion.