ACTH stimulation Test (SST)
The ACTH stimulation test (also called the short Synacthen test or SST) is a quick, safe blood test that checks how well your adrenal glands respond to stress. It is the standard way to diagnose adrenal insufficiency (Addison’s disease) and related conditions. The test involves injecting a small amount of synthetic ACTH and measuring cortisol levels before and after the injection. Most people find it straightforward, and the results help your doctor decide the next steps.
What Is the ACTH Stimulation Test (SST)?
The ACTH stimulation test measures your adrenal glands’ ability to produce cortisol when stimulated by ACTH (adrenocorticotropic hormone). ACTH is normally released by the pituitary gland to signal the adrenals to release cortisol, especially during stress. In this test, a synthetic version of ACTH (called Synacthen or cosyntropin) is injected, and your cortisol response is tracked over time. In Bangladesh, the test is often referred to as the short Synacthen test (SST).
If the adrenal glands are damaged or the pituitary is not sending enough ACTH, the cortisol response will be blunted. This makes the SST a reliable tool for identifying adrenal insufficiency.
Why Might Your Doctor Recommend This Test?
Your doctor may order the ACTH stimulation test if you have symptoms that suggest your adrenal glands are not working properly. Common reasons include:
- Suspected primary adrenal insufficiency (Addison’s disease): Symptoms like chronic fatigue, unexplained weight loss, low blood pressure, darkening of the skin (hyperpigmentation), and salt cravings.
- Suspected secondary adrenal insufficiency: Caused by a pituitary or hypothalamic problem, often due to long-term steroid use, pituitary tumors, or head injury. Symptoms may be similar but without skin darkening.
- Monitoring adrenal function: In people who have been on long-term corticosteroids and are being weaned off, or after pituitary surgery.
- Unexplained electrolyte imbalances: Such as low sodium or high potassium.
Only a qualified endocrinologist can decide if this test is appropriate based on your full history and physical exam.
How to Prepare for the ACTH Stimulation Test
Preparation is simple but important. Here is what you need to know:
- Medication review: Some medications can affect cortisol levels, especially steroids (e.g., prednisolone, dexamethasone, hydrocortisone), estrogen-containing pills, and certain seizure medications. Your doctor will tell you if you need to stop any medication temporarily – never stop or change your medication without your doctor’s explicit instruction.
- Fasting: Usually, no fasting is required. You can eat and drink normally unless your doctor advises otherwise.
- Timing: The test is best done in the morning (around 8–9 AM) when natural cortisol levels are highest.
- Inform your doctor: Tell your doctor about all prescription drugs, over-the-counter medicines, and supplements you take.
The Procedure: What to Expect Step by Step
| Step | Description |
|---|---|
| 1. Baseline blood draw | A small blood sample is taken from a vein in your arm to measure your baseline cortisol level. |
| 2. Injection of synthetic ACTH | A nurse or doctor injects a small dose (usually 250 micrograms) of Synacthen into your vein or muscle. The injection may cause a brief warm or flushing sensation. |
| 3. Timed blood draws | After 30 minutes (and sometimes again at 60 minutes), another blood sample is taken to see how your cortisol level has risen. |
| 4. Completion | You can leave after the last blood draw. The entire test takes about 1–2 hours. You can resume normal activities immediately. |
The test is done as an outpatient procedure – you do not need to stay in hospital. Side effects are rare but may include mild nausea, flushing, or a metallic taste, which resolve quickly.
Understanding Your Results
Your results will show cortisol levels at baseline and after stimulation. In a normal response, cortisol rises significantly (usually to a peak above a lab-specific threshold). If the rise is blunted or absent, it suggests adrenal insufficiency.
Important: Only an endocrinologist should interpret your results. The specific cut-off values vary between laboratories and depend on the assay used. Your doctor will compare your results to the reference range provided by the lab and consider your symptoms and medical history before making a diagnosis. An abnormal result does not automatically mean you have Addison’s disease – further tests (such as ACTH level, renin, aldosterone, or imaging) may be needed.
Risks and Side Effects
The ACTH stimulation test is very safe. The most common side effects are mild and temporary:
- Flushing or warmth – a brief sensation that passes quickly.
- Nausea or metallic taste – rare and short-lived.
- Bruising at the injection site – possible but harmless.
Serious allergic reactions are extremely rare. The main risk is not related to the test itself but to misinterpretation of results if the patient is on medications that affect cortisol levels. That is why proper preparation and an experienced endocrinologist are essential.
Cost of the ACTH Stimulation Test in Bangladesh
| Service | Approx. BDT Range | Notes |
|---|---|---|
| ACTH stimulation test (SST) – basal + 1 post‑injection sample | ৳2,500 – ৳4,500 | Price depends on lab quality, location, and whether it is a standalone test or part of a panel. |
| ACTH stimulation test with 2 post‑injection samples (30 & 60 min) | ৳3,500 – ৳6,000 | More comprehensive; often recommended for better accuracy. |
| Additional tests (e.g., ACTH level, renin, aldosterone) | Variable | Often added if adrenal insufficiency is suspected; ask your doctor about the full panel. |
Note: Prices are approximate and change over time. Costs vary by city (Dhaka, Chittagong, etc.), the reputation of the lab, and whether the test is done in a hospital or standalone diagnostic center. Always confirm the current rate with the lab or hospital before scheduling.
Find an Endocrinologist in Your Division
If your doctor recommends an ACTH stimulation test, you will need an endocrinologist to order and interpret it. Use the table below to find specialists in your division.
| Division | Find a doctor |
|---|---|
| Dhaka / ঢাকা | Endocrinologist Doctors in Dhaka |
| Chattogram / চট্টগ্রাম | Best Endocrinologist Doctors in Chattogram |
| Khulna / খুলনা | Endocrinologist Specialists in Khulna |
| Rajshahi / রাজশাহী | Endocrinologists in Rajshahi |
| Rangpur / রংপুর | Rangpur Endocrinologist Doctors |
| Sylhet / সিলেট | Endocrinologist Doctors in Sylhet |
| Barishal / বরিশাল | Recommended Endocrinologist Doctors in Barishal |
| Mymensingh / ময়মনসিংহ | Top Endocrinologist Doctors in Mymensingh |
Frequently Asked Questions
Do I need to stop my steroid medicines before the ACTH stimulation test?
Certain steroid medicines can affect the results, but you should never stop them on your own. Suddenly stopping steroids — especially prednisolone or dexamethasone — can cause a dangerous drop in blood pressure or an adrenal crisis. Your doctor will tell you exactly which medicines to hold and for how long. If you have not received clear instructions, ask before the test day.
Does the test have to be done in the morning?
Most centres perform the test in the morning, usually between 8 and 9 am, because natural cortisol levels follow a daily rhythm and are highest at that time. A morning baseline makes the results easier to interpret. However, some protocols allow the test later in the day. Follow the time slot your doctor or laboratory assigns — do not change it on your own.
What is the difference between the short and long Synacthen test?
The short Synacthen test (SST) takes about 30–60 minutes and is the standard first-line check for adrenal insufficiency. The long test uses a slower infusion or repeated doses over several hours or days and is sometimes used to distinguish primary adrenal disease (Addison’s disease) from secondary causes related to the pituitary gland. Your endocrinologist will decide which version is needed based on your history and initial results.
Is the ACTH stimulation test safe during pregnancy or for children?
The test is generally considered safe in both groups, and synthetic ACTH has been used in clinical practice for decades. However, pregnancy can change cortisol levels, and children may need smaller doses. Always inform your doctor if you are pregnant or if the test is for a child, so the dose and interpretation can be adjusted appropriately.
What happens if my results are abnormal?
An abnormal result does not automatically mean you have Addison’s disease. Your doctor will usually repeat the test or order additional blood tests, such as a baseline ACTH level, and may arrange imaging of the adrenal glands. You may be referred to an endocrinologist, who will guide treatment — such as steroid replacement — only after confirming the diagnosis. Do not start any treatment based on a single result.
Key takeaways
The ACTH stimulation test (SST) is a simple, low-risk procedure that provides crucial information about your adrenal health. If you have symptoms suggesting adrenal insufficiency, talk to your doctor about whether this test is right for you. Always have the test ordered and interpreted by a qualified endocrinologist, and never adjust your medications without medical guidance. With proper preparation and follow-up, the SST can help guide effective treatment.
Sources
The following sources are from international journals, government health agencies, or recognized medical organizations:
- ACTH Stimulation Test – Mayo Clinic (mayoclinic.org)
- Cosyntropin (ACTH) Stimulation Test – MedlinePlus (medlineplus.gov)
- ACTH Stimulation Test – Endocrine Society (via PubMed Health) (pubmed.ncbi.nlm.nih.gov)
- World Health Organization — ACTH stimulation Test (SST) (who.int)
- MedlinePlus — ACTH stimulation Test (SST) (medlineplus.gov)
- CDC — ACTH stimulation Test (SST) (cdc.gov)