Question 1

What TSH level is too high?

Accepted Answer

Most labs flag results above about 4.0 to 4.5 mIU/L. Between that and 10 mIU/L, clinicians often repeat the test and check free T4 before deciding on treatment. Above 10 mIU/L, treatment is more often recommended, but the decision depends on symptoms, age, pregnancy plans and other results.

Question 2

Can stress affect TSH?

Accepted Answer

Short-term stress has little direct effect, but serious illness, poor sleep and some medicines can shift TSH for a while. That is why a borderline result is usually repeated once you are well.

Question 3

Is TSH different in pregnancy?

Accepted Answer

Yes. TSH often falls in early pregnancy, and many labs and clinicians use lower, trimester-specific ranges. If you are pregnant or planning to be, ask your clinician which range applies to you.

Question 4

Should I fast before a TSH test?

Accepted Answer

Fasting is usually not needed for TSH alone. Many clinicians prefer a morning test for consistency, and if you take thyroid medication you may be asked to take it after the blood draw.