Response to Methopyrapone (Su-4885) and Pyrogen Test in Idiopathic Hypopituitary Dwarfism1

Abstract

The oral methopyrapone (Su-4885) test and the pyrogen stimulation test have been carried out in 13 idiopathic hypopituitary dwarfs. In addition, the response to the pyrogen test was studied in 2 normal children. Ten of the hypopituitary dwarfs showed an abnormal response to the Su-4885 test. The normal children and 12 of the hypopituitary dwarfs showed a significant rise in the plasma concentration of unconjugated 17-hydroxycorticosteroids (17-OHCS) 2 and 4 hr after the injection of the pyrogenic agent. In the majority of cases, the pyrogen injection was followed by a small but definite increase in the excretion of 17-OHCS. Nine of the hypopituitary dwarfs responded adequately to the pyrogen test subsequent to having an abnormal response to the Su-4885 test. The significance of the dichotomy in the response to these 2 tests is discussed. It is concluded that the idiopathic hypopituitary dwarfs have enough functioning pituitary tissue to respond normally to the stress induced by Piromen and possibly other types of acute stress. The lesion responsible for the abnormal Su-4885 test in idiopathic hypopituitarism could be located anywhere within the hypothalamic-pituitary unit.