TSH Stimulation by TRH (Thyrotropin Releasing Hormone) Test
Short Name: TRH Stimulation Test
Also known as: TSH Stimulation Test, TRH Stimulation Test, Thyrotropin Releasing Hormone Stimulation Test, TRH Test
TSH Stimulation by TRH (Thyrotropin Releasing Hormone) Test test available at DNA Labs India for ₹1,287. Uses Chemiluminescent Immunoassay (CLIA) on Serum samples. Results in Reports are generated daily and are usually available within 24 hours after the laboratory receives the last timed specimen.. Free home collection in 300+ cities across India.
🩺 Medically Reviewed By
Dr Ramarao Paidisetty
Consultant Biochemist · Reg: 21504
Last reviewed: September 7, 2026
Overview
This test is used to determine whether a low TSH/low thyroid hormone state is caused by pituitary or hypothalamic disease. It measures the TSH response to exogenous TRH, providing functional information about pituitary TSH reserve that cannot be obtained from basal thyroid function tests alone.
- Test Code
- 3709
- CPT Code
- 80438
- ICD Code
- E03.9
- Price
- ₹1,287
- Sample Type
- Serum
- Result Time
- Reports are generated daily and are usually available within 24 hours after the laboratory receives the last timed specimen.
- Fasting Required
- Yes (8 hours)
- Method
- Chemiluminescent Immunoassay (CLIA)
Sample Collection
Overnight fasting is mandatory. Please inform your treating physician about all current medications, especially thyroid hormone replacement, glucocorticoids, and oral contraceptives. The TRH injection is not supplied by DNA Labs India; it must be arranged by the treating physician before the test.
Method: Venipuncture
Laboratory Analysis
A fasting baseline blood sample is collected first. TRH is then administered as an IV bolus over 30 seconds. Additional blood samples are collected at 30 minutes and 60 minutes after the injection. You may experience transient flushing, nausea, or a strange taste, but these symptoms usually resolve quickly.
Report Delivery
You may resume normal eating and activities after sample collection. The intravenous site may remain slightly tender; apply pressure if needed. Your treating endocrinologist will interpret the results and guide further management.
Timeline: Reports are generated daily and are usually available within 24 hours after the laboratory receives the last timed specimen.
Patient Instructions
About This Test
Who Should Get This Test
This test is used to determine whether a low TSH/low thyroid hormone state is caused by pituitary or hypothalamic disease. It measures the TSH response to exogenous TRH, providing functional information about pituitary TSH reserve that cannot be obtained from basal thyroid function tests alone.
How to Prepare
- Overnight fasting is mandatory; plain water may be taken.
- TRH injection must be arranged by the treating physician; the laboratory does not supply it.
- Draw fasting baseline specimen, then administer TRH as IV bolus 7 µg/kg body weight (maximum 500 µg) over 30 seconds.
- Draw additional specimens at 30 minutes and 60 minutes.
- All containers must be clearly marked with the exact time of collection.
- Submit all timed specimens with a single test request form.
- Ship specimens refrigerated or frozen as per sample stability guidelines.
Doctor's Notes
Reviewed by Dr Ramarao Paidisetty — MBBS, MD (Biochemistry) · Reg. No. 21504
"In selected cases with suspected central hypothyroidism, this dynamic test helps identify whether the defect is in the pituitary or the hypothalamus. It should be interpreted alongside basal free T4, TSH, and pituitary imaging."
Last medically reviewed: September 7, 2026
Test Parameters & Specifications
Sample Stability
- Unlabelled or incorrectly labelled timed specimens.
- Missing timed samples where the dynamic pattern cannot be interpreted.
- Haemolysed or lipemic samples.
- Non-fasting specimen when fasting was required.
- Samples not transported within stability guidelines.
Understanding Your Results
High baseline TSH with exaggerated and prolonged TSH response to TRH.
Suggests thyroid gland failure with intact pituitary-hypothalamic axis.
Low or normal TSH with blunted or absent TSH rise at 30 and 60 minutes.
Suggests pituitary disease or reduced pituitary TSH reserve.
Low TSH with delayed TSH peak at 60 minutes.
Suggests hypothalamic TRH deficiency.
TSH rises appropriately after TRH, peaks around 30 minutes, and falls by 60 minutes.
Indicates normal functional integrity of the pituitary thyrotrophs.
If you have an abnormal TSH response or persistent symptoms such as fatigue, weight changes, depression, or menstrual irregularities, consult an endocrinologist for further evaluation and management.
Limitations
- ⚠TRH injection may not be readily available and is not supplied by DNA Labs India.
- ⚠Not routinely indicated as a first-line thyroid function test.
- ⚠Results must be interpreted with clinical findings and pituitary imaging, as an absent response does not identify the anatomical lesion.
- ⚠Reference values vary between assays and laboratories.
- ⚠Blunted TSH response may also occur in depression, renal failure, prolonged fasting, and other non-thyroidal conditions.
Risks & Considerations
- ●Mild pain, redness, or bruising at the venipuncture site.
- ●Transient flushing, nausea, or metallic taste after TRH injection.
- ●Urinary urgency shortly after TRH injection.
- ●Rarely, hypotension or allergic reaction.
Interfering Factors
- ●Thyroid hormone replacement and anti-thyroid drugs can alter TSH response.
- ●Glucocorticoids, dopamine, and somatostatin analogues may blunt TSH rise.
- ●Pregnancy and oestrogen therapy affect TSH values.
- ●Acute or chronic non-thyroidal illness can cause abnormal TSH response.
- ●Amiodarone, lithium, and iodine-containing contrast agents can interfere with the thyroid axis.
Compare With Similar Tests
| Test | TSH Stimulation by TRH (Thyrotropin Releasing Hormone) Test | ||
|---|---|---|---|
| Comparison | TSH Stimulation by TRH (Thyrotropin Releasing Hormone) Test |
Frequently Asked Questions
What is the TSH Stimulation by TRH test?
Why is the TRH injection given?
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Do I need to fast before this test?
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Is the TRH stimulation test safe?
Does DNA Labs India supply the TRH injection?
Can I take my regular thyroid medicines before the test?
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