370
- What are the characteristic features of CAH due to 11β-hydoxylase
defi ciency?
11 β-hydoxylase defi ciency is the second most common cause of CAH with an
incidence of 1 in 100,000. Girls with 11β-hydoxylase defi ciency manifest with
genital ambiguity at birth without salt-wasting crisis. Hypertension, the cardi-
nal differentiating feature of 11β-hydoxylase defi ciency from 21α-hydroxylase
defi ciency, is not present in the neonatal period. It usually manifests between 3
and 4 years of age as distal renal tubules are resistant to the action of mineralo-
corticoids in early childhood. Boys with 11β-hydoxylase defi ciency present at
2–4 years of age with premature pubarche, penile enlargement (GIPP), and
hypertension. The levels of serum 17(OH)P are elevated; however, the 17(OH)
P values are much lower than those found in classical CAH due to
21 α-hydroxylase defi ciency. The diagnosis of 11β-hydoxylase defi ciency can
be confi rmed by the estimation of 11-deoxycortisol, which is invariably ele-
vated, and by genetic analysis (Fig. 10.17 ).- Can patients with 11β - hydoxylase defi ciency have salt - wasting crisis?
Although 11β-hydoxylase defi ciency is characteristically associated with
hypertension, some children with 11β-hydoxylase defi ciency may have
salt- wasting crisis during infancy. The exact mechanism remains elusive; how-
ever, the proposed mechanisms include accumulation of natriuretic metabolites
of pregnenolone like 16-hydroxy pregnenolone (which counteract the
mineralocorticoid effect of DOCA) and end-organ resistance to mineralocorti-
coids. Interestingly, salt-wasting crisis can occur after initiation of glucocorticoidabFig. 10.17 ( a ) Acne and upper lip hair in a 4-year-old boy with CAH due to 11β-hydoxylase
defi ciency. ( b ) Pubic hair Tanner stage P2, testicular volume 2 ml with disproportionate penile
enlargement suggestive of gonadotropin-independent precocious puberty. Child had hypertension
which responded to glucocorticoids
10 Congenital Adrenal Hyperplasia