Isolated ACTH deficiency.

Isolated ACTH deficiency is a rare disorder. We report four cases of this disease which presented to the Department of Endocrinology at Leeds General Infirmary over a one-year period. The diagnostic clinical and biochemical features of each case are discussed and the pertinent literature is reviewed. The clinical investigations vary somewhat between cases as the four patients presented in markedly different ways. Well validated dynamic endocrine investigations were employed including glucagon stimulation test (GST) and the corticotrophin releasing hormone (CRH) test (using 100 micrograms of human CRH with samples for ACTH and cortisol). Two patients probably had CRH deficiency and two had ACTH deficiency. All the cases are instructive, illustrating different features of this heterogeneous condition. We conclude that the diagnosis of this condition may be difficult due to the varied clinical presentation. We suggest that it is commoner than previously thought and that the precision of diagnosis can be improved using the CRH test.