ADRENOCORTICAL INSUFFICIENCY

Adrenocortical insufficiency, i.e. impaired secretion of adrenocortical hormones, may be primary (adrenal disorders) or secondary, due to pituitary ACTH or hypothalamic CRH deficiency.

Adrenocortical deficiency results from many con- genital/acquired lesions of the hypothalamus, pituitary or adrenals (Table 22.10). Congenital adrenal hyperplasia (Ch 22.5.2) or adrenal hemorrhage in septic/asphyxiated newborns is the commonest cause of primary adrenal insufficiency in infancy, while older cases are usually

TABLE 22.10: Causes of adrenal insufficiency

Secondary (Pituitary/Hypothalamic lesions)

• Congenital

- Isolated CRH/ACTH deficiency (Genetic)

- Pituitary aplasia/hypoplasia

• Acquired

- Intracranial infections/trauma/surgery

- Pituitary/hypothalamic tumors

- Iatrogenic: Sudden steroid withdrawal

Primary (Adrenal defects)

• Congenital

- Adrenal aplasia/hypoplasia

- Isolated cortisol/aldosterone deficiency

- Hormonal synthesis defects: CAH

- Adrenoleukodystrophy

- End-organ resistance: Pseudohypoaldosteronism

• Acquired

- Addison disease: Autoimmune, tuberculosis

- Infection: Waterhouse-Friderichsen syndrome

• Iatrogenic

- Drugs: Ketoconazole, anticonvulsants

- Adrenectomy

due to Addison disease (Ch 22.5.3) or acute adrenal insufficiency in severe infections, e.g. meningococcemia (Waterhouse-Friderichsen syndrome).

Secondary adrenal insufficiency is usually seen after sudden withdrawal of steroids after prolonged therapy, due to suppression of the hypothalamo-pituitary axis.

22.5.2