What Are Dynamic Endocrine Tests?
Dynamic endocrine testing refers to a group of specialized stimulation or suppression tests used to evaluate how endocrine glands respond under controlled physiological challenge. Unlike static hormone measurements, which capture a single hormone level at one point in time, dynamic tests assess the functional reserve and regulatory capacity of the hypothalamic-pituitary-adrenal (HPA) axis and other endocrine systems. These tests are essential for diagnosing conditions such as adrenal insufficiency, non-classical congenital adrenal hyperplasia (NCCAH), Cushing's syndrome, and growth hormone disorders.
At District Endocrine, these tests are performed in-office under direct physician supervision — no hospital or infusion center visit required.
ACTH Cosyntropin Stimulation Test
The ACTH cosyntropin stimulation test (also called the corticotropin stimulation test or Synacthen test) is the gold-standard diagnostic test for both adrenal insufficiency and non-classical congenital adrenal hyperplasia (NCCAH) due to 21-hydroxylase deficiency.
How the Test Is Performed
The test is performed in the morning (ideally before 9 AM) to coincide with peak cortisol secretion. For women being evaluated for NCCAH, the test should be performed during the early follicular phase of the menstrual cycle, and patients should not have taken any glucocorticoid medications in the days prior. The protocol involves:
- 1Baseline blood draw (T=0) — Serum cortisol and 17-hydroxyprogesterone (17-OHP) are measured before stimulation.
- 2Cosyntropin injection — 250 mcg of synthetic ACTH (cosyntropin) is administered intravenously or intramuscularly.
- 3Post-stimulation blood draw (T=60 min) — Serum cortisol and 17-OHP are measured 60 minutes after injection.
A cortisol level below 18–20 mcg/dL at 60 minutes suggests adrenal insufficiency. For NCCAH diagnosis, a stimulated 17-OHP level above 30 nmol/L (approximately 1000 ng/dL) is diagnostic of NCCAH due to 21-hydroxylase deficiency (CYP21A2 deficiency), per the Endocrine Society guidelines.
Diagnosing Adrenal Insufficiency
Adrenal insufficiency occurs when the adrenal glands do not produce enough cortisol. It may be primary (Addison's disease — the adrenal glands themselves are damaged), secondary (pituitary failure to secrete ACTH), or tertiary (hypothalamic failure). The cosyntropin stimulation test reliably detects primary and most cases of secondary adrenal insufficiency by challenging the adrenal cortex to produce cortisol in response to ACTH stimulation. An inadequate cortisol response confirms the diagnosis and guides initiation of glucocorticoid replacement therapy.
Diagnosing Non-Classical Congenital Adrenal Hyperplasia (NCCAH)
Non-classical congenital adrenal hyperplasia (NCCAH), also called late-onset CAH, is a mild form of 21-hydroxylase deficiency caused by mutations in the CYP21A2 gene. It is one of the most common autosomal recessive disorders, with a prevalence of approximately 1 in 100–1,000 individuals depending on ethnicity. NCCAH causes an accumulation of 17-hydroxyprogesterone (17-OHP), the substrate of 21-hydroxylase, and excess androgen production.
NCCAH is frequently misdiagnosed as PMOS (PCOS), polycystic ovarian disease, or idiopathic hirsutism because its clinical features overlap significantly: irregular periods, acne, hirsutism, infertility, and elevated androgens. A published 2026 prospective study confirmed that basal 17-OHP measurement alone misses a significant proportion of NCCAH cases, reinforcing the ACTH stimulation test as the definitive diagnostic standard — particularly in women presenting with oligoanovulation and hyperandrogenism.
Other Dynamic Endocrine Tests Offered In-Office
🔑 Key Takeaways
- ACTH cosyntropin stimulation testing is the gold-standard test for adrenal insufficiency and NCCAH (non-classical CAH).
- NCCAH due to 21-hydroxylase (CYP21A2) deficiency is a common, frequently missed cause of hirsutism, irregular periods, and infertility in women.
- Basal 17-OHP alone misses a significant portion of NCCAH cases — the stimulation test is required for definitive diagnosis.
- A stimulated 17-OHP above 30 nmol/L at 60 minutes confirms NCCAH; a cortisol below 18–20 mcg/dL confirms adrenal insufficiency.
- All dynamic tests are performed in-office at District Endocrine — no hospital or infusion center visit needed.
- Dexamethasone suppression testing for Cushing's syndrome and GH suppression testing for acromegaly are also available.
- Results are integrated with your full clinical picture for accurate diagnosis and treatment planning.
Providers Offering Dynamic Endocrine Testing
