Congenital Adrenal Hyperplasia

Congenital adrenal hyperplasia is a group of heritable disorders associated with inability or reduced ability to produce cortisol. Due to cortisol insufficiency, excess of adrenocorticotropic hormone (ACTH) is released from anterior pituitary causing unremitting stimulation of adrenal cortex, causing hyperplasia. In many cases, deficiency of aldosterone also causes hyponatremia and hyperkalemia. Majority of cases are due to 21-hydroxylase deficiency. The classic form is the most common cause of atypical genitalia in 46 XX newborns. Salt losing crisis which occurs early in life in many patients needs urgent treatment with fluids, replacement with hydrocortisone and fludrocortisone, and correction of electrolyte imbalance, so as to prevent a fatal outcome. Long-term therapeutic goals, unlike other forms of adrenal insufficiency, are twofold—replacing the missing adrenal cortex hormones and suppressing the excess androgen levels. Improved strategies in dosing and timing of medications and close follow-up for adequacy of treatment, growth and complications related to the disease and treatment have improved the outcome of patients with this disorder. Clinicians should also consider patients’ quality of life and consult mental health professionals as deemed necessary. Other forms of CAH are uncommon; their incidence varies with country and ethnic background. This chapter describes the pathophysiology, clinical features, and management of 21-hydroxylase deficiency in detail and briefly describes other forms of CAH like CYP11B1 (11β-hydroxylase) deficiency, CYP17A1 deficiency, 3β-HSD2 deficiency, congenital lipoid adrenal hyperplasia, and P450 oxidoreductase deficiency.