Q7.

What is TRH testing?

This testing is to get the blood sample to test the serum TSH basic figure. After inject 500ug of TRH in vein, then get serum again after 30min and 60min to test TSH again. The normal person after 40 year old can increase 2-5 times or at least 6uU/ml. Female is sensitive than male. The reaction of 40 years old male is much slow, 2uU/ml for them is normal. Hypothyroid is not sensitive for such testing. This testing is very helpful to hypothyroid who do not have much increased serum thyroid incretion. 80% Graves who only is incretion related and do not have clinic hypothyroid also do not have reaction to the TRH. The hypothyroidism is sensitive of the TRH reaction. But it is not necessary for them to have the test since the TSH figure can be the index of hypothyroidism. TRH testing can judge the pathological changes of recur hypothyroidism is in pituitary or the below part of thalamencephalon.

Thalamencephalon hypothyroidism presents lingering reaction. But pituitary hypothyroidism reaction will decrease. Estrogen, alkaline and anti-hypothyroid medicine can strengthen the reaction to TRH. But thyroid preparation and L-dopa can restrain the reaction of TRH. Within 2 min after the TRH injection, about half patients can have rose-cheeked, naupathia and emiction. According to what said before, TRH testing is replaced by the high sensitive TSH testing.

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