Described in 1932 by Harvey Cushing, an American neurosurgeon, Cushing's syndrome is due to an excess production of CORTISOL. It can thus result from an ADRENAL tumour secreting cortisol, or from a PITUITARY GLAND tumour secreting ACTH (ADRENOCORTICOTROPHIC HORMONE) and stimulating both adrenal cortexes to hypertrophy and secrete excess cortisol. It is sometimes the result of ectopic production of ACTH from non-endocrine tumours in the LUNG and PANCREAS.

The patient gains weight and the obesity tends to have a characteristic distribution over the face, neck, and shoulder and pelvic girdles. Purple striae develop over the abdomen and there is often increased hairiness (hirsutism). The blood pressure is commonly raised and the bone softens as a result of OSTEOPOROSIS. The best test to establish the diagnosis is to measure the amount of cortisol in a 24-hourly specimen of urine. Once the diagnosis has been established, it is then necessary to undertake further tests to determine the cause.