Urinary excretion of carnitine and serum concentrations of carnitine and lipids in patients with hypofunctional endocrine diseases: involvement of adrenocorticoid and thyroid hormones in ACTH-induced augmentation of carnitine and lipids metabolism.

The promoting effect of ACTH on carnitine and lipid metabolism was studied in patients with various endocrine hypofunctions. The results were compared with those of normal subjects. In adrenocortical insufficiency, hypothyroidism and hypopituitarism urinary excretion of carnitine was significantly lower than in normal subjects. On intramuscular injection of synthetic beta1-24 ACTH-Z urninary excretion of carnitine in normal subjects increased sixfold on the day of the injection and returned to the pretreatment level on the third day. Serum concentrations of carnitine and FFA increase in parallel with carnitine excretion, while serum triglyceride was lowered in response to ACTH administration. These responses were totally lacking or substantially suppressed in patients with the above endocrine insufficiencies. In hypothyroid and hypopituitary patients substitution therapy restored the responses to ACTH in the same fashion as those in normal subjects. These findings suggest that the promoting effect of ACTH on carnitine and lipid metabolism requires the presence of intact adrenocortical and thyroid functions.