11ß-Hydroxylase deficiency accounts for approximately 5% of cases of CAH. The prevalence of this autosomal recessive disorder is 1 in 100,000 births. A deficiency of this enzyme impairs the conversion of deoxycorticosterone to corticosterone and the conversion of 11-deoxycortisol to cortisol. The resultant decrease in cortisol production causes an increase in ACTH secretion (due to a loss of negative feedback). The ACTH stimulates excessive production of the adrenal androgens, deoxycorticosterone and 11-deoxycortisol. The excess androgens will virilise female foetuses as in 21-hydroxylase deficiency. In 11ß-Hydroxylase there is hypertension (high blood pressure), and it is this that distinguishes it from 21-hydroxylase deficiency. This high blood pressure is thought to result from the mineralocorticoid activity of deoxycorticosterone.
A milder late-onset form of 11ß-Hydroxylase deficiency presents later with symptoms of hypertension, hypokalaemia, precocious puberty and in women, hirsutism. The treatment consists of replacement of physiological amounts of glucocorticoids.