From the Guidelines
Congenital adrenal hyperplasia (CAH) should be diagnosed with serum 17-hydroxyprogesterone (17-OHP) as the primary screening test, along with other essential laboratory tests including ACTH stimulation test, serum electrolytes, plasma renin activity, and serum androgen levels. To diagnose CAH, the following laboratory tests are essential:
- Serum 17-hydroxyprogesterone (17-OHP), which is typically elevated in CAH, as noted in the context of adrenal incidentalomas and the consideration for screening for CAH with 17-hydroxyprogesterone 1
- ACTH stimulation test to confirm the diagnosis by measuring 17-OHP levels before and after ACTH administration
- Serum electrolytes (sodium, potassium) to assess for salt-wasting
- Plasma renin activity, which is often elevated in salt-wasting forms
- Serum androgen levels including testosterone, DHEA, and androstenedione to evaluate the degree of androgen excess
- Genetic testing for CYP21A2 mutations, the gene most commonly affected in CAH Additional helpful tests include:
- Serum cortisol to assess adrenal insufficiency
- Aldosterone levels to evaluate mineralocorticoid production CAH presents with varying severity, from life-threatening salt-wasting crises in newborns to milder forms with virilization in females, precocious puberty in males, or adult-onset symptoms like infertility or hirsutism, highlighting the importance of early diagnosis and appropriate management, as discussed in the context of managing adrenal incidentalomas and considering the potential for congenital adrenal hyperplasia 1. The management of CAH involves lifelong glucocorticoid replacement (typically hydrocortisone) to suppress excess androgen production and, in salt-wasting forms, mineralocorticoid replacement (fludrocortisone) to maintain electrolyte balance, which is crucial for preventing long-term complications and improving quality of life.
From the Research
Definition of Congenital Adrenal Hyperplasia
Congenital adrenal hyperplasia (CAH) is a group of autosomal recessive disorders that encompass enzyme deficiencies in the adrenal steroidogenesis pathway, leading to impaired cortisol biosynthesis 2. It is characterized by androgen excess secondary to impaired steroidogenesis in the adrenal glands 3.
Labs to Order for Diagnosis
The diagnosis of CAH is most commonly made by confirming elevations of:
- 17-hydroxyprogesterone (17-OHP) 4
- Androstenedione (ANST) 4
- 21-deoxycortisol (21-deoxy) is a more specific marker for 21-hydroxylase deficiency and may be used to replace 17-OHP in the future 5 In some cases, measurement of:
- Progesterone (PGSN) 4
- Deoxycorticosterone (DOC) 4 may be necessary for diagnosis.
Types of CAH
There are several types of CAH, including:
- 21-hydroxylase deficiency, which is the most common type 3, 4
- 11β-hydroxylase deficiency 3
- 3β-hydroxysteroid dehydrogenase deficiency 3, 5 Each type has different laboratory findings and may require different treatments.
Newborn Screening
Newborn screening programs that measure 17-OHP are used to detect CAH due to 21-hydroxylase deficiency 5. However, this screening is not without false positives, and 21-deoxy may be a more specific marker for 21-hydroxylase deficiency in the future 5.