Table of ContentsView All
View All
Table of Contents
Purpose of Test
Limitations
Risks and Contraindications
Before the Test
What to Bring
During the Test
After the Test
Interpreting Results
As a result of these issues, it is used primarily as a research tool. The test also has limited availability as a diagnostic test for thyroid disease outside the United States.
Laura Porter / Verywell
Thyroid hormone production requires many steps. Your hypothalamus, located in your brain, monitors the conditions of your body and secretesthyrotropin-releasinghormone (TRH) when you need more thyroid hormones. TRH prompts your brain’s pituitary gland to release thyroid-stimulating hormone (TSH).
TSH stimulates the thyroid gland itself to make thyroid hormones, T4 and T3, which increase your body’s metabolism to provide you with energy.
While symptoms that can arise when something goes amiss are generally owed to anunderactive or overactive thyroid,there is arange of possible causes, and theright treatmentdepends on which one applies to you.
(Secondary and tertiary hypothyroidism are both consideredcentral hypothyroidism.)
The TRH stimulation test is primarily considered a tool for differentiating secondary hypothyroidism from tertiary hypothyroidism when T3 and T4 levels are not enough to draw a firm conclusion.
The TRH stimulation test usually triggers a rise in TSH, and the extent of the change may help identify secondary and tertiary hypothyroidism. However, the TSH response to the TRH stimulation test is not reliable, and the results do not usually provide more insight into the cause of thyroid disease than TSH, T4, and T3 levels.
Thyroid Function Tests and Normal Ranges
A rapid increase in thyroid hormone levels is the biggest concern with the TRH stimulation test, as this can cause increases or decreases in blood pressure or pulse, raising the risk of blood clots,stroke, transient ischemic attack (TIA), or seizures.
Other notable potential side effects of the test include:
Contraindications
If you have a pituitary tumor, stimulation with TRH can cause pituitary apoplexy, which is dangerous bleeding of the pituitary gland that may require emergency surgical intervention.
This test can also interfere with thyroid medications, and the side effects can be more severe if you take medications for adrenal disease.
The use of steroids,aspirin (acetylsalicylic acid), or medications used for Parkinson’s disease can alter the results, making interpretation unreliable.
If you are set to have a TRH stimulation test done, this means that you are likely part of a research study, or that your thyroid hormone results are unusual enough for your healthcare providers to request that you have this test.
Your healthcare provider will discuss specific instructions, such as whether you should continue to take your usual medications before, during, and after the test. This depends on whether your blood pressure tends to fluctuate or to run too high or too low.
Timing
You should expect to devote a few hours to this test. You will have blood tests taken 30 and 60 minutes after receiving the injection. Additionally, your medical team may want to observe you for several hours after the test to watch for any medical complications. If you experience any complications, you can expect your recovery time to take hours or even days, as the medical team stabilizes you.
Location
Your test may take place in the hospital or in a healthcare provider’s office.
A TRH stimulation test is done in a medical facility where your vital signs (blood pressure, heartbeat, breathing rate) can be monitored closely.
What to Wear
You may be able to have this test while wearing your regular clothes, or you may be asked to change into an examination gown. Your injection is most likely going to be in a blood vessel in your arm, and your blood will probably be drawn from your arm as well, so it is best to wear clothes with sleeves that are easy to roll up so that your lower to mid-arm can be easily exposed.
Food and Drink
This test is meant to be performed in the morning after overnight fasting from food and drink.
Cost and Health Insurance
The TRH stimulation test is not approved for standard medical use. Given this, and that it is not commonly done, the cost is not easy to predict. If your healthcare provider requested that you have this test due to exceptional circumstances, contact your health insurance provider to confirm the details of payment, whether you will be expected to pay a portion of the cost, and how much that portion is.
If you are having this test as part of a research study, it may be covered as part of the research protocol. Check with your medical team to verify.
When you arrive for the test, you should bring your order form, a form of identification, and documentation of any research protocol that you are part of. If your insurance company has approved the test, you should bring documentation of the approval, as well as your insurance card.
It is best to bring someone who can drive you home after the test.
At your test, you may see your healthcare provider, and you will see a nurse or a phlebotomist (specialist in drawing blood) as well.
Pre-Test
You will need to check in, sign consent forms, and possibly consent to payment. Before the test begins, you may be hooked up to a blood pressure and pulse monitor so that you can be monitored continuously or at 15-minute intervals.
Throughout the Test
A blood draw will usually be taken from a vein in your arm, and possibly from your hand. Because you will have your blood collected more than once, your nurse or phlebotomist may use both your right and left arms.
For each collection, the practitioner will find a vein, wrap an elastic band above the area where your blood will be drawn, clean the area, insert the needle, and collect the blood. You may feel a brief, sharp pain when the needle enters your arm, and you may experience mild discomfort while the needle is in place.
This should take about 30 seconds each time, after which the elastic band and the needle are removed and the area is covered with a bandage or gauze.
Alternatively, you may have atemporary portplaced, which is kept in place for the duration of the test so that you will not need multiple needle sticks. For this, you will have a needle inserted into a vein, just like with a standard blood draw. This needle is attached to a tube, creating an “entry point” that can be used every time a practitioner needs to access your vein.
You may experience the same brief, sharp pain and/or mild discomfort when the catheter is inserted, but the infusion alone is not painful. When done, the infusion site will be covered with a bandage.
It is the TRH infusion that can cause side effects, which can begin immediately, or at any time within the first few days after the test. If you experience dizziness, headaches, palpitations, shortness of breath, or vision changes, you should report them to the medical team right away.
Two more blood samples will be taken to measure your TSH level 30 minutes after your TRH injection, and again 60 minutes after the injection.
Post-Test
You may feel some side effects after your test. The response to this test is not easy to predict with certainty.
You may have delayed effects of thyroid hormone overstimulation lasting for days. And, after experiencing an increased thyroid response, you may actually have a resulting suppression of your thyroid hormones. These effects can begin days after the test and may last for a few more.
If you experience insomnia, hyper-alertness, unusual hunger, lack of energy, or adry mouth, you can expect them to gradually improve and then resolve within a week.
When to Seek Urgent CareIf you experience dizziness, palpitations, vision changes, chest pain, vomiting, severe headaches, or convulsions, get urgent medical attention right away.
When to Seek Urgent Care
If you experience dizziness, palpitations, vision changes, chest pain, vomiting, severe headaches, or convulsions, get urgent medical attention right away.
The results of the blood test may be available within a few hours after your test, or they may take a few days to be returned if your blood sample needs to be sent to another lab.
The key feature of the TRH stimulation test is the change in TSH level after the TRH injection.
An inappropriately low or normal TSH with low T4 and T3 suggests central hypothyroidism, while high TSH with low T4 and T3 suggests primary hypothyroidism.
It is important to consider standard thyroid test values when interpreting these results. Because TSH, T4, and T3 levels can provide adequate insight into the cause of hypothyroidism in the majority of cases, the TRH stimulation test does not typically add a great deal of useful information.
If you need to have your test repeated, you should wait at least one week for the effects of the injection to wear off. Generally, repeating the test is rarely indicated, and it should only be repeated if your diagnosis remains unclear.
If you are taking part in a research study, the protocol may require repeating the test. Consider this in advance before committing to be a participant.
A Word From Verywell
Given the lack of availability of the TRH stimulation test, its limited value, and the fact that it is not FDA approved, it is unlikely that you will need to have this test. However, if you are going to, it is best to familiarize yourself with all of the risks and side effects so you can make the most educated decision.
8 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
Pirahanchi Y, Jialal I.Physiology, thyroid stimulating hormone (TSH). Treasure Island, FL. StatPearls Publishing.
Endocrineweb.Thyroid gland: Overview.
Merck Manual Professional Version.Hypothyroidism (myxedema).
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Drugs.com.Thyrotropin releasing hormone TRH.
Wang HF, Huang CC, Chen YF, Ho DM, Lin HD.Pituitary apoplexy after thyrotropin-releasing hormone stimulation test in a patient with pituitary macroadenoma.J Chin Med Assoc. 2007;70(9):392–395. doi:10.1016/S1726-4901(08)70026-1
Gupta V, Lee M.Central hypothyroidism.Indian J Endocrinol Metab. 2011 Jul;15(Suppl 2):S99-S106. doi:10.4103/2230-8210.83337
Altıncık A, Demir K, Çatlı G, Abacı A, Böber E.The Role of Thyrotropin-Releasing Hormone Stimulation Test in Management of Hyperthyrotropinemia in Infants.J Clin Res Pediatr Endocrinol. 2015 Sep;7(3):211-6. doi: 10.4274/jcrpe.1985.Pijnacker T, Knies M, Galac S, Sanders K, Mol JA, Kooistra HS.TRH-induced secretion of adrenocorticotropin and cortisol in dogs with pituitary-dependent hypercortisolism.Vet Q. 2018 Dec;38(1):72-78. doi: 10.1080/01652176.2018.1521537.Rijks J, Penders B, Dorenbos E, Straetemans S, Gerver WJ, Vreugdenhil A.Pituitary response to thyrotropin releasing hormone in children with overweight and obesity. Sci Rep. 2016 Aug 3;6:31032. doi: 10.1038/srep31032.
Altıncık A, Demir K, Çatlı G, Abacı A, Böber E.The Role of Thyrotropin-Releasing Hormone Stimulation Test in Management of Hyperthyrotropinemia in Infants.J Clin Res Pediatr Endocrinol. 2015 Sep;7(3):211-6. doi: 10.4274/jcrpe.1985.
Pijnacker T, Knies M, Galac S, Sanders K, Mol JA, Kooistra HS.TRH-induced secretion of adrenocorticotropin and cortisol in dogs with pituitary-dependent hypercortisolism.Vet Q. 2018 Dec;38(1):72-78. doi: 10.1080/01652176.2018.1521537.
Rijks J, Penders B, Dorenbos E, Straetemans S, Gerver WJ, Vreugdenhil A.Pituitary response to thyrotropin releasing hormone in children with overweight and obesity. Sci Rep. 2016 Aug 3;6:31032. doi: 10.1038/srep31032.
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