High TSH levels usually mean the thyroid is underactive, which is called hypothyroidism. TSH levels can change due to factors like age, sex, and pregnancy. TSH influences thyroid hormones that control ...

A doctor can test your TSH levels with a blood test to diagnose thyroid disease. Normal TSH levels range from 0.4-4.0 mUI/mL, which indicates proper thyroid function. You can treat abnormal TSH levels ...