Parathyroid hormone is normal in renal stone patients with idiopathic hypercalciuria and high fasting urinary calcium.

In a group of patients with idiopathic hypercalciuria and an increased fasting urinary calcium excretion we re-examined the question: does secondary hyperparathy-roididsm exist? Eight out of 51 patients with calcium renal stones had a high calcium excretion in both fasting and in 24 h urines. The carboxyl-terminal immunoreactive PTH (iPTH) values in these patients were 16 +/- 5 ngeq/ml (M +/- SD), no higher than the iPTH values in the other groups, e.g. normocalciuric patients had an iPTH of 23 +/- 8 ngeq/ml. The existence of secondary hyperparathyroidism in a subgroup of stone patients with increased fasting urinary calcium excretion is questionable.