From the Research
For suspected congenital adrenal hyperplasia (CAH) in a newborn without screening, I recommend ordering serum 17-hydroxyprogesterone (17-OHP) as the primary diagnostic test, along with electrolytes (sodium, potassium, chloride), blood glucose, plasma renin activity, and serum aldosterone. A comprehensive adrenal steroid panel including 11-deoxycortisol, androstenedione, testosterone, and DHEA-sulfate will help characterize the specific enzyme deficiency, as suggested by 1. Collect blood samples before starting any steroid treatment if the patient is stable. An ACTH stimulation test may be necessary to confirm the diagnosis in borderline cases, as seen in 2. Obtain a karyotype for all infants with ambiguous genitalia. Abdominal/pelvic ultrasound should be performed to evaluate adrenal glands and internal genital structures. Urinalysis for specific gravity and urinary steroid profiling can provide additional diagnostic information. These tests are crucial because CAH, most commonly caused by 21-hydroxylase deficiency, can present with salt-wasting crisis, ambiguous genitalia in females, or may be asymptomatic initially in males, as discussed in 3. Early diagnosis is essential to prevent life-threatening adrenal crisis, especially in salt-wasting forms, and to guide appropriate hormone replacement therapy. It is also important to consider that some cases of CAH may be missed on newborn screening, as noted in 2, and that non-CAH primary adrenal insufficiency may present with similar symptoms, as seen in 4. Furthermore, the use of 21-deoxycortisol as a more specific marker for 21OHD has been suggested, as discussed in 5.
Some key points to consider when ordering labs and diagnostics for suspected CAH in a newborn without screening include:
- The importance of early diagnosis to prevent life-threatening adrenal crisis
- The need for a comprehensive adrenal steroid panel to characterize the specific enzyme deficiency
- The use of ACTH stimulation testing to confirm the diagnosis in borderline cases
- The importance of obtaining a karyotype for all infants with ambiguous genitalia
- The role of abdominal/pelvic ultrasound in evaluating adrenal glands and internal genital structures
- The potential for non-CAH primary adrenal insufficiency to present with similar symptoms
- The potential benefits of using 21-deoxycortisol as a more specific marker for 21OHD.
Overall, a thorough diagnostic workup is essential for suspected CAH in a newborn without screening, and should include a combination of laboratory tests, imaging studies, and clinical evaluation, as supported by 1, 3, 2, 4, 5.