The Medical Relevance Of Diseases Of The Adrenal Cortex: Cushing’s Syndrome (Hypercortisolism)

Disorders of the adrenal cortex may lead to alteration in the levels of the different hormones to different degrees.

Cushing’s Syndrome (Hypercortisolism)

Cushing’s syndrome is caused by persistent oversecretion of glucocorticoids. In addition to increased levels of cortisol in blood, loss of the normal diurnal rhythm is also a prominent feature.

Etiology

ACTH-dependent conditions: 1. Bilateral adrenal hyperplasia: In 70% of these, a small adenoma involving the basophils (Cushing’s disease) or chromophobes is present. Sometimes the abnormality is in the production, and release of CRF from the hypothalamus.

2. Ectopic ACTH secretion: This is seen as a paraneoplastic syndrome in bronchogenic carcinoma, carcinoids, pancreatic carcinoma, nonteratogenic ovarian carcinoma, neuroblastoma and ganglioma.

3. Iatrogenic: Regular therapeutic administration of exogenous ACTH leads to Cushing’s syndrome.

ACTH-independent conditions: 1. Adenomas or carcinomas of the adrenal cortex. The tumour is usually unilateral.

2. Iatrogenic: Use of pharmacological doses of glucocorticoids. Cushing’s syndrome is seen in Indian subjects not infrequently. It has been reported from all parts of India. Pituitary-dependent adrenal hyperplasia and adrenal tumours are more frequent in women in the fourth and fifth decades.

The symptoms depend directly on the overproduction and raised blood levels of glucocorticoids. Almost all features can be attributed to gluconeogenesis, protein catabolism and androgenic effects of cortisol.

General features: The affected subject is plethoric with rounded appearance of the face (moon face). There is characteristic obesity with deposition of fat over the neck, shoulders, abdomen and hips. This is called the “buffalo type” of obesity.

The integument: Hirtuitism develops in many cases and it is particularly troublesome in women. Face, chest and other regions are affected. Acne may develop. The hair-line may recede over the temporal regions (temporal baldness) or even general baldness may result. Skin shows painless striae which develop as reddish streaks over the thighs, gluteal regions, abdomen, axillae and outer aspect of the arms. Striae are formed as a result of rupture of subcutaneous collagenous tissue. In severe cases, the overlying skin may be stretched and thinned out and it tends to rupture and ulcerate. Repair of wounds is considerably delayed. Wound dehiscence is common after surgery. Scar formation is poor. Bruising, purpura and pigmentation are seen in some cases. Some cases show secondary polycythemia.

Hypertension and its complications are common. Muscles are easily fatigable, flabby, and atrophic. Proximal muscles show myopathic changes. Psychiatric symptoms like depression and melancholia may be the presenting features in some. Amenorrhea and clitoromegaly develop in women. Males show loss of libido and impotence. In those with overproduction of estrogenic hormones infertility may occur. Bones show osteoporosis which is more prominent in the axial skeleton. Fractures are common.

Finally, diabetic state develops in the majority of cases. This may be latent in some cases. Diabetic complications may develop. Hypernatremia, hypokalemia and fluid retention may develop. In addition to this general symptomatology, special findings occur depending on the etiological factor.