Overview
TSH is produced by the pituitary gland and regulates the thyroid. Its level is a sensitive indicator of how well the gland is working.
Why it's done
It is ordered for fatigue, weight change, hair loss, cycle disturbances or to monitor thyroid disease.
How to prepare
No special preparation is needed. If you take thyroid medication, confirm the timing with your doctor.
What to expect
A venous blood draw.
Understanding the results
A high TSH often indicates hypothyroidism and a low TSH hyperthyroidism. Free T4 and T3 are often added to clarify. An endocrinologist interprets the result.