Cortisol Suppression by Dexamethasone Overnight High Dose Test
Short Name: High Dose Dexamethasone Suppression Test
Also known as: High Dose Dexamethasone Suppression Test, Overnight High Dose DST, Dexamethasone Suppression Test
Cortisol Suppression by Dexamethasone Overnight High Dose Test test available at DNA Labs India for ₹1,287. Uses Chemiluminescent Immunoassay on Serum samples. Results in Reports are typically available on the same day or within 24 hours after sample collection.. Free home collection in 300+ cities across India.
🩺 Medically Reviewed By
Dr Pasupathy Arumugam
Consultant Pathologist · Reg: 21521
Last reviewed: September 7, 2026
Overview
The primary purpose of this test is to diagnose Cushing's syndrome by assessing the suppressibility of cortisol production. It helps differentiate between various causes of hypercortisolism, such as pituitary adenomas, adrenal tumors, or ectopic ACTH production, guiding further diagnostic and treatment decisions.
- Test Code
- 355
- Price
- ₹1,287
- Sample Type
- Serum
- Result Time
- Reports are typically available on the same day or within 24 hours after sample collection.
- Fasting Required
- Yes (10 hours)
- Method
- Chemiluminescent Immunoassay
Sample Collection
Fast overnight for at least 10 hours before the baseline blood sample at 8 am. Avoid strenuous activity and stress.
Method: Venipuncture
Laboratory Analysis
A healthcare professional will collect blood via venipuncture from a vein in the arm, ensuring proper labeling of samples with time and date.
Report Delivery
Apply pressure to the puncture site to prevent bleeding. Resume normal activities, but avoid heavy lifting for a few hours.
Timeline: Reports are typically available on the same day or within 24 hours after sample collection.
Patient Instructions
About This Test
Who Should Get This Test
The primary purpose of this test is to diagnose Cushing's syndrome by assessing the suppressibility of cortisol production. It helps differentiate between various causes of hypercortisolism, such as pituitary adenomas, adrenal tumors, or ectopic ACTH production, guiding further diagnostic and treatment decisions.
How to Prepare
- Fast overnight before baseline sample collection at 8 am
- Take 4 mg dexamethasone tablet orally at 11 pm as prescribed
- Provide second blood sample at 8 am next morning without fasting
- Mark both containers with time and date drawn
- Ship samples refrigerated or frozen using provided packaging
Doctor's Notes
Reviewed by Dr Pasupathy Arumugam — MBBS, MD (Pathology) · Reg. No. 21521
"This test is crucial for diagnosing Cushing's syndrome and assessing cortisol regulation, helping in early detection and management of adrenal disorders."
Last medically reviewed: September 7, 2026
Test Parameters & Specifications
Sample Stability
- Hemolyzed or lipemic samples
- Improper labeling or missing time/date
- Insufficient sample volume (<1 mL)
- Incorrect container type or damaged tubes
- Samples not shipped refrigerated or frozen as required
Understanding Your Results
Normal response, suggests no Cushing's syndrome; cortisol regulation is intact.
Abnormal response, indicative of Cushing's syndrome; further testing like ACTH measurement or imaging is recommended.
Consult an endocrinologist if you experience persistent symptoms of high cortisol or if test results are abnormal for timely diagnosis and management.
Limitations
- ⚠Does not specify the exact cause of Cushing's syndrome
- ⚠Requires precise timing of dexamethasone administration and sample collection
- ⚠False positives may occur in conditions like depression or alcoholism
- ⚠Not suitable for patients on ongoing steroid therapy
- ⚠May require confirmatory tests for definitive diagnosis
Risks & Considerations
- ●Minor bruising or pain at the blood draw site
- ●Rare risk of infection or dizziness
- ●Potential side effects from dexamethasone such as nausea or headache
Interfering Factors
- ●Use of steroid therapy or other medications
- ●Stressful conditions or sleep deprivation
- ●Recent surgery, illness, or trauma
- ●Pregnancy or hormonal contraceptives
- ●Alcohol consumption or smoking
Frequently Asked Questions
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