Growth hormone secretion in primary and secondary hyperparathyroidism.

[familial hypocalciuric hypercalcemia]

Primary hyperparathyroidism (PHP ) is associated with impaired GH secretion . Whether this effect is due to hypercalcemia or to increased serum PTH concentration is unclear . However , patients with familial hypocalciuric hypercalcemia (FHH ), who have normal PTH and increased serum calcium concentrations , also have an impaired GH secretion , suggesting that calcium rather than PTH is responsable for this effect on GH secretion . To further investigate this issue , 10 consecutive patients with secondary hyperparathyroidism (SHP ) due to vitamin D deficiency were evaluated by the GH response to GHRH +arginine (Arg ) test . A group of 60 consecutive untreated PHP patients served as controls . Mean GH response to GHRH +Arg test was 15 .8 +/-14 microg /l and 37 .5 +/-16 microg /l (p <0 .001 ) in PHP and in SHP patients , respectively . Forty -two out of 60 (70 %) PHP patients had a suppressed or blunted GH response , whereas all SHP patients had normal GH response . The results of the present study confirm and extend our previous observations that PHP is associated with an impaired GH secretion in the majority of cases , and indicate that SHP patients have no abnormality of GH secretion . Thus , hypercalcemia rather than increased serum PTH is responsible for the abnormality of GH secretion .