Laboratory Findings in Congenital Adrenal Hyperplasia
Primary Diagnostic Markers
- Serum cortisol is low or inappropriately normal for the clinical state, according to the Journal of Internal Medicine 1
- Plasma ACTH is clearly elevated due to lack of negative feedback from cortisol deficiency, as reported by the Journal of Internal Medicine 1
- ACTH stimulation test shows inadequate cortisol response, with peak cortisol <500 nmol/L (or <18 μg/dL) diagnostic of adrenal insufficiency, as stated by the Journal of Internal Medicine and Praxis Medical Insights 1, 2
Electrolyte Abnormalities
- Hyponatremia is present due to aldosterone deficiency, impaired free water clearance from cortisol deficiency, and increased vasopressin/angiotensin II, according to the Journal of Internal Medicine 1
- Hyperkalemia results from aldosterone deficiency, impaired glomerular filtration, and acidosis, as reported by the Journal of Internal Medicine 1
- Metabolic acidosis is common, as stated by the Journal of Internal Medicine 1
- Mild to moderate hypercalcemia occurs in 10-20% of patients at presentation, according to the Journal of Internal Medicine 1
Androgen Markers
- Elevated testosterone (>2.5 nmol/L in females) is characteristic, as reported by the Journal of Neurology, Neurosurgery and Psychiatry 3
- Elevated androstenedione (>10.0 nmol/L) may be present, according to the Journal of Neurology, Neurosurgery and Psychiatry 3
- Elevated DHEAS (age-dependent thresholds: >3800 ng/mL for ages 20-29, >2700 ng/mL for ages 30-39) is observed, as stated by the Journal of Neurology, Neurosurgery and Psychiatry 3
Mineralocorticoid Axis
- Plasma renin activity (PRA) is increased in salt-wasting forms, according to the Journal of Internal Medicine 1
- Serum aldosterone is low despite elevated renin, as reported by the Journal of Internal Medicine 1
Additional Laboratory Findings
- Mild eosinophilia and lymphocytosis may be present, as stated by the Journal of Internal Medicine 1
- Anemia can occur, according to the Journal of Internal Medicine 1
- Increased liver transaminases are sometimes observed, as reported by the Journal of Internal Medicine 1
- Hypoglycemia is more common in children but can occur in adults, potentially causing seizures, according to the Journal of Internal Medicine 1
- TSH levels may be mildly elevated (typically 4-10 IU/L) due to lack of cortisol's inhibitory effect on TSH production, as stated by the Journal of Internal Medicine 1