TRH Test

Thyrotropin releasing hormone also known as thyrotropin releasing factor or TRF, protirelin or thyroliberin is a hormone which is responsible for stimulating the pituitary gland so that it can secrete Thyroid Stimulating Hormone or TSH, which in turn stimulates the thyroid gland to secrete T3 & T4 thyroid hormones.

TRH test is mostly required in case of thyroid related disorders like secondary hypothyroidism, when the doctor would like to determine the root cause of the disease.

The test

The TRH test generally involves administering a small portion or amount of TRH into the veins of a person.

Once the TRH enters the blood, the TSH level in the body is measured.

Stimulus: TRH (TRH-Ferring ELEA or HRT) intravenous bolus in 2 minutes.

Dosage: Adults: 200 ug.

Children: 9 ug / kg. Weight.

Preconditions for the patient:

The patient should come with an empty stomach for the test and should also take sufficient amount of rest before the test is conducted.

After intravenous injection, the patient should remain in the laboratory for subsequent blood draws to be conducted as prescribed.

If the patient needs to take any medication for hormonal function, it should only be taken after the test is completed.


In normal individuals TSH concentration increases rapidly reaching maximal response between 20 and 30 minutes, then declines slowly returning to baseline within 2 to 3 hours. Overall the average increase in TSH is 15 UUI / ml.

The answer is classified as:

  • Plain: less than 3 UUI / ml.
  • Subnormal: between 3 and 4.7 UUI / ml.
  • Normal: 4.7- to 25 UUI / ml.
  • hyper responsiveness: over 25 UUI / ml

Based on the results of the test, the doctors determine the nature of the disease and the appropriate treatment for the same, which includes dosage of different drugs or medications.