A baby is born with ambiguous genitalia. Which of the following statements is true?

Ambiguous genitalia at bih is a medical emergency, not only for psychological reasons for the parents but also because hirsute female infants with congenital adrenal hyperplasia (CAH) may die if undiagnosed. CAH is an autosomally inherited disease of adrenal failure that causes hyponatremia and hyperkalemia because of lack of mineralocoicoids. Although a thorough physical examination is helpful, especially for inguinal testes, other tests that are required include a karyotype, serum electrolytes, and blood or urine assays for progesterone, 17a-hydroxyprogesterone, and androgens such as dehydroepiandrosterone sulfate. Radiologic studies are usually not needed, but a laparotomy is sometimes necessary for ectopic gonadectomy.