Cosyntropin
Also known as: Cortrosyn, ACTH 1-24, Tetracosactide
Key Facts: Cosyntropin
- Category
- Hormonal
- FDA Status
- FDA Approved
- Clinical Status
- FDA Approved - Diagnostic use
- Administration
- IV or intramuscular
- Typical Dose
- Limited community data available
- Frequency
- See research protocols
- Duration
- Single diagnostic dose
Mechanism of Action
Natural ACTH is 39 amino acids long, but the part that switches on the adrenal cortex sits in the first 24. Cosyntropin keeps exactly that piece. When injected, it binds the melanocortin-2 receptor (MC2R) on adrenal cortex cells, the same docking site real ACTH uses, and triggers a rapid burst of cortisol synthesis and release. The response is fast, with cortisol climbing within 30 minutes. Because it copies the active signal so cleanly, a healthy adrenal gland reacts to it just as it would to the real hormone, which is what makes it a clean diagnostic probe rather than a blunt one.
Research Summary
Cosyntropin is FDA-approved and clinically established. The standard adult dose is 250 micrograms (0.25 mg) given IV or IM, with serum cortisol measured at baseline, 30, and 60 minutes. A normal response is generally a cortisol level reaching at least roughly 18 micrograms per deciliter, though exact cutoffs depend on the assay used (LC-MS/MS methods use somewhat lower thresholds). A blunted rise points to adrenal insufficiency: primary (the adrenal gland itself is failing, as in Addison disease) or, with caveats, secondary or tertiary (the pituitary or hypothalamus is not driving it). It is one of the most validated dynamic endocrine tests in medicine, not a fringe or experimental compound. Worth knowing: this is a diagnostic agent, so the body of research is about test accuracy and interpretation, not about therapeutic benefit.
Dosing Information
Typical Dosingⓘ
Community experience
Limited community data available
See research dosing
See research protocols
Research Dosingⓘ
Scientific studies
Standard diagnostic protocols
Doses from Studies
250 mcg IV/IM (standard)
1 mcg IV (low-dose)
Duration
Single diagnostic dose
Administration
IV or intramuscular
Timing & Administration
Best Time to Take
Morning or as directed
Follow recommended protocol
Food Recommendation
With or without food
Why This Timing?
Timing may vary based on individual response and goals. Consistency is generally more important than specific timing.
Possible Side Effects
Not everyone experiences these effects. Individual responses vary based on dosage, duration, and personal factors.
- ●Hypersensitivity reactions (common)
- ●Injection site reactions
- ●Bradycardia or tachycardia
- ●Blood pressure changes
- ●Headache
- ●Intended for diagnostic use
- ●FDA approved (Cortrosyn)
References
- https://www.ncbi.nlm.nih.gov/books/NBK555940/
- https://pmc.ncbi.nlm.nih.gov/articles/PMC3262370/
- https://www.labcorp.com/test-menu/resources/acth-stimulation-test
Research This Peptide Further
Frequently Asked Questions
What does Cosyntropin do?
Cosyntropin is a synthetic fragment of the body's own stress hormone, ACTH, stripped down to the first 24 amino acids that do the actual work. Doctors do not use it to treat anything. They inject it to ask the adrenal glands a single question: can you make cortisol on demand? It is the backbone of the standard test for adrenal insufficiency.
How does Cosyntropin work?
Natural ACTH is 39 amino acids long, but the part that switches on the adrenal cortex sits in the first 24. Cosyntropin keeps exactly that piece. When injected, it binds the melanocortin-2 receptor (MC2R) on adrenal cortex cells, the same docking site real ACTH uses, and triggers a rapid burst of cortisol synthesis and release. The response is fast, with cortisol climbing within 30 minutes. Because it copies the active signal so cleanly, a healthy adrenal gland reacts to it just as it would to the real hormone, which is what makes it a clean diagnostic probe rather than a blunt one.
Is Cosyntropin FDA approved?
Yes, Cosyntropin is FDA approved. FDA Approved - Diagnostic use
What are the side effects of Cosyntropin?
Reported side effects include: Hypersensitivity reactions (common), Injection site reactions, Bradycardia or tachycardia, Blood pressure changes, Headache. Individual responses vary based on dosage, duration, and personal health factors.
What is the typical dose of Cosyntropin?
Community-reported common dose: Limited community data available (See research protocols). Range: See research dosing. Administration: IV or intramuscular. Community-reported doses. Not medical advice. Consult healthcare provider.
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