Congenital Adrenal Hyperplasia (CAH)

CAH is a group of autosomal recessive disorders affecting cortisol biosynthesis in the adrenal cortex

• Most common: 21-hydroxylase deficiency (→ ~90% of cases)
  • Gene: CYP21A2

Clinical Presentation

Presents in neonatal period

• Girls:
  • Ambiguous genitalia (clitoromegaly, labioscrotal fusion)
• Boys:
  • Normal genitalia → but present 1–2 weeks after birth with:
    • Vomiting
    • Dehydration
    • Hypotension
    • Hyponatremia
    • Hyperkalemia
    • Shock
• ↑ 17-hydroxyprogesterone (screening test)
• Electrolytes: hyponatremia, hyperkalemia
• Elevated ACTH
• Low cortisol
• Genetic testing (CYP21A2 mutations)

Treatment

Acute Crisis:

• IV hydrocortisone
• IV fluids + dextrose
• Correct electrolytes (esp. hyperkalemia)

Maintenance:

• Glucocorticoids (hydrocortisone, prednisone)
• Mineralocorticoids (fludrocortisone) for salt-wasting forms
• Salt supplementation in infants

Surgical:

• Genital reconstruction for females (if needed, delayed until later childhood)

Buzzwords:

• "Female infant with ambiguous genitalia and hypotension"
• "Electrolyte abnormalities: hyponatremia + hyperkalemia"
• "Increased 17-hydroxyprogesterone on newborn screen"

Think of CAH when:

• Neonate has shock and ambiguous genitalia
• Child has early pubarche or growth acceleration
• Adolescent girl with acne, hirsutism, irregular periods