[The effects of synthetic 1-34 fragment of human PTH on kidney and bone receptors in man. Use of the Ellsworth-Howard test]

The authors propose to study parathyroid hormone receptors in humans by means of a test "inspired by the Ellsworth-Howard test" using the active synthetic 1-34 fragment of the hormone PTH-1-34. The use of this test in 44 patients (29 healthy subjects, 7 patients with idiopathic hypercalciuria 5 cases of Paget's disease, 1 patient with idiopathic hypoparathyroidism, 2 cases of basal cell nevus syndrome) who received different doses of this substance intravenously, revealed a marked dose-dependent stimulation of adenyl-cyclase as objectified by an increase in urinary excretion of cyclic AMP (AMPcU). Distal tubular calcium reabsorption was also significantly affected as demonstrated by a decrease in urinary calcium in the first hours following administration of the 1-34 fragment even in the case of idiopathic hypercalciuria. In comparison to the "classical" Ellsworth-Howard test, however, no significant urinary phosphate response was observed during the present test. Similarly, urinary hydroxyproline and phosphate and calcium blood levels remained stable. As the results obtained for the case of hypoparathyroidism demonstrate, this easily performed test is useful for valuating parathormone receptors in kidney by means of two sensitive parameters (AMPcU and the ratio of fractional urinary calcium to urinary creatinine). In addition to its action, synthetic fragment h PTH-1-34 offers the advantage of being totally innocuous.