The effect of o,p'-DDD on adrenal steroid replacement therapy requirements.

Two patients with adrenal carcinoma treated with 2,2-bis (2-chlorophenyl-4-chlorophenyl)-1,1-dichloroethane (o,p'-DDD) as adjuvant therapy were studied. Both patients developed hypoadrenalism while on o,p'-DDD and apparently adequate dexamethasone replacement therapy. The hypoadrenalism was overcome by increasing steroid replacement therapy. Dexamethasone levels were measured in the serum by radioimmunoassay and shown to be lowered by o,p'-DDD therapy. A study of the absorption and disappearance of dexamethasone from the circulation in response to a (1 mg oral dose indicated that the steroid was absorbed normally but was cleared more rapidly from the circulation of these two patients than from normal controls. This may be due to a change in the type of metabolites excreted. It is suggested that many of the reported side-effects of o,p'-DDD may be due to hypoadrenalism and may be controlled by greatly increasing the steroid replacement dose. The adequacy of corticosteroid replacement therapy may best be assessed by monitoring the levels of ACTH.