Dexamethasone Suppression Test for Cortisol: Booking, Price, and Results
About Dexamethasone Suppression Test for Cortisol: Booking, Price, and Results
| Field | Value |
|---|---|
| Also Known As | DST, Cortisol suppression test, Overnight dexamethasone suppression test, Low-dose dexamethasone suppression test (LDDST), High-dose dexamethasone suppression test (HDDST) |
| Sample Type | Venous blood (serum) or 24-hour urine |
| Fasting Required | No fasting required; however, dexamethasone must be taken at a specified time (usually 11 p.m. the night before) |
| Report Time | 1 to 3 days |
| Recommended For | Individuals with suspected cortisol excess; not well-standardised in children |
| Price | Starting at ₹1500 |
What Is a Dexamethasone Suppression Test for Cortisol?
The dexamethasone suppression test for cortisol checks how the body responds to a synthetic steroid called dexamethasone. Normally, dexamethasone signals the body to reduce cortisol production. This test shows whether that suppression happens correctly. Also known as the DST or cortisol suppression test, it is usually ordered by a doctor when there are signs of excess cortisol in the body. A blood sample is drawn from a vein in the arm.
What Does a Dexamethasone Suppression Test for Cortisol Measure?
This test evaluates key aspects of how the body handles cortisol after dexamethasone is taken. The parameters below are drawn from verified clinical data.
| Parameter | What It Shows |
|---|---|
| Serum cortisol (after dexamethasone, overnight method) | Whether the adrenal glands correctly reduce cortisol output after receiving a suppressive signal |
| Urinary-free cortisol (standard method, day 3) | The amount of cortisol excreted in urine over 24 hours |
Why Is a Dexamethasone Suppression Test for Cortisol Done?
Doctors order this test when a patient shows signs that their cortisol levels may be too high. Below are the common reasons it is requested.
Common Symptoms That May Require This Test
The following symptoms often prompt a doctor to request a dexamethasone suppression test for cortisol:
- Unexplained weight gain, especially around the abdomen
- High blood pressure without a clear cause
- Easy bruising or slow wound healing
- Purple stretch marks on the skin
- A rounded, puffy face (sometimes called moon face)
- Excessive hair growth in women (hirsutism)
- Unexplained muscle weakness
Conditions This Test Can Help Detect
A DST can help identify several conditions related to abnormal cortisol production:
- Cushing syndrome, a condition caused by persistently high cortisol levels.
- ACTH-dependent Cushing syndrome, where a pituitary gland or other tumour drives excess cortisol.
- ACTH-independent Cushing syndrome, where an adrenal gland abnormality causes excess cortisol.
How to Prepare and What to Expect
The dexamethasone suppression test procedure is straightforward, but a few steps must be followed precisely for accurate results.
Do You Need to Fast?
No, fasting is not required for this test. However, the timing of your dexamethasone dose and sample collection is critical and must be followed exactly as instructed by your doctor.
Practical Tips Before Your Test
Before your dexamethasone suppression test preparation, keep the following in mind:
- Tell your doctor about every medication you are currently taking, including over-the-counter drugs and supplements.
- Women taking oral contraceptive pills should speak to their doctor, as these may need to be stopped at least 6 weeks before the test to avoid inaccurate results.
- Avoid alcohol in the days leading up to the test.
- Try to manage stress levels before sample collection, as high stress can affect cortisol readings.
- Wear a loose-fitting top or short sleeves to make the blood draw easier.
Step-by-Step Procedure
Here is what to expect in the overnight dexamethasone suppression test procedure:
- At 11:00 p.m. on the night before your test, take the prescribed dose of dexamethasone exactly as instructed by your doctor. Typically, 1 mg is used for the low-dose test, while 8 mg is used for the high-dose test.
- The overnight low-dose method is the most common version of this test. Taking dexamethasone with milk or an antacid can help avoid stomach discomfort.
- The next morning at around 8 a.m., visit the laboratory or receive a home collection visit from a phlebotomist.
- A trained professional will draw a small amount of blood from a vein in your arm using a sterile needle. This takes only a few minutes.
- The blood sample is separated and prepared for analysis in the laboratory.
- Cortisol levels in the sample are measured and compared against the expected suppression threshold.
Another standard method for the dexamethasone suppression test uses a urine sample:
- Urine samples are collected over 3 consecutive days using 24-hour urine collection containers to measure cortisol levels.
- On the second day of the test, dexamethasone is started at the prescribed dose (either 0.5 mg for the low-dose test or 2 mg for the high-dose test) and taken orally every 6 hours. The specific dose used depends on the type of test ordered by your doctor.
- The medication is continued for a total duration of 48 hours.
- It is important to take each dose exactly on schedule and follow all collection instructions carefully for accurate test results.
Factors That Can Affect Accuracy
Several factors can interfere with the dexamethasone suppression test for cortisol results:
- Medications such as anti-seizure drugs, rifampicin, corticosteroids, oestrogen, and certain antifungals.
- Obesity, uncontrolled stress, diabetes or depression.
- Alcohol use in the period before the test.
- Poor absorption of dexamethasone due to gut problems.
- Incorrect timing of the dexamethasone dose or the sample collection.
Understanding Your Dexamethasone Suppression Test for Cortisol Results
Results from this test must always be reviewed with a doctor who is familiar with your full health history. The table below shows the reference ranges used for interpretation.
| Parameter | Normal Range | Unit |
|---|---|---|
| Serum cortisol (overnight low-dose) | Less than 1.8 | mcg/dL |
| High-dose overnight suppression | Greater than 50% decrease from baseline | % suppression |
| Urinary-free cortisol (standard low-dose, day 3) | Less than 10 | mcg/day |
| Urinary-free cortisol (standard high-dose, day 3) | Greater than 90% decrease in urinary-free cortisol | % suppression |
These ranges are general guidelines. Your doctor will interpret your results based on your age, health history, and other factors. Always consult a qualified healthcare professional for personalised medical advice.
Results During Special Conditions
Certain situations can affect how results are read:
- Oestrogen-containing medications and pregnancy raise a protein called cortisol-binding globulin, which can produce misleading results on this test.
- Conditions such as severe obesity, depression, alcohol use disorder, kidney failure, and uncontrolled diabetes are also known to cause falsely elevated cortisol readings.
- Some medications, including phenytoin, carbamazepine, and rifampicin, speed up the breakdown of dexamethasone in the body, which can make cortisol appear unsuppressed even when it should be.
How to Maintain Healthy Levels
These general wellness habits may support balanced cortisol levels over time:
- Aim for 7 to 8 hours of sleep each night and keep a regular sleep routine.
- Manage daily stress through physical activity, breathing exercises, or other relaxation methods.
- Avoid excessive alcohol and maintain a healthy weight through a balanced diet.
Lupin Diagnostics Dexamethasone Suppression Test for Cortisol Price and Home Collection
The dexamethasone suppression test for cortisol is available at Lupin Diagnostics starting at approximately ₹1500, with home sample collection offered across major cities.
| City | Approximate Price (₹) |
|---|---|
| Mumbai | ₹1500 |
| Bhopal | ₹1500 |
| Bengaluru | ₹1500 |
| Hyderabad | ₹1500 |
| Chennai | ₹1500 |
| Kolkata | ₹1500 |
| Pune | ₹1500 |
| Guwahati | ₹1500 |
Prices are indicative and may vary by location. Please confirm the current price at the time of booking.
How to Book
- Select the test on the Lupin Diagnostics website.
- Choose your city and preferred time slot.
- Opt for home sample collection by a certified phlebotomist, or visit your nearest Lupin Diagnostics centre.
- Receive your report via email or WhatsApp within the stipulated turnaround time.
Home Collection
Lupin Diagnostics offers home sample collection for the dexamethasone suppression test across cities, so you can have a trained phlebotomist visit at your preferred time. All samples are processed in NABL-accredited laboratories, and your digital report is delivered securely via email or WhatsApp.
Frequently Asked Questions
The DST checks whether your body appropriately lowers cortisol production after taking a synthetic steroid called dexamethasone. It is mainly used to screen for Cushing syndrome, a condition caused by persistently high cortisol levels. The test can also help determine whether excess cortisol originates from the adrenal glands, the pituitary gland, or another source.
Dexamethasone suppression test preparation is simple. At 11 p.m. the night before, take the prescribed 1 mg dexamethasone tablet, ideally with milk or an antacid to minimise stomach upset. The next morning at around 8 a.m., attend the laboratory or await your home collection visit. No fasting is needed.
Several medicines can affect dexamethasone suppression test for cortisol results, including anti-seizure drugs, antibiotics, corticosteroids, oestrogen-based medications, oral contraceptives, and diuretics. Always give your doctor a complete list of everything you are taking well before the test date.
If cortisol stays above the normal threshold, the result is considered abnormal. This may point to Cushing syndrome or another condition causing excess cortisol production. Further tests are usually needed before a firm diagnosis can be made, so consult your doctor for the next steps.
The dexamethasone suppression test is considered safe. Dexamethasone is taken only once, so side effects are unlikely. The blood draw carries a small chance of minor bruising or discomfort at the needle site, which typically settles quickly.
Yes. Conditions such as uncontrolled stress, severe obesity, alcohol use disorder, kidney failure, and uncontrolled diabetes can keep cortisol levels elevated, producing a result that looks abnormal even when Cushing syndrome is not present. Your doctor will factor in your overall health when interpreting the result.
An endocrinologist, a doctor who specialises in hormone disorders, is best placed to interpret dexamethasone suppression test for cortisol results. Diagnosing Cushing syndrome involves assessing symptoms, medical history, and often additional hormone tests or imaging alongside the DST.
Dexamethasone Suppression Test for Cortisol: Booking, Price, and Results
