TSH (Thyroid Stimulating Hormone) is produced by the pituitary gland and signals the thyroid to produce thyroid hormones. A TSH test is the primary screening tool for thyroid disorders.
How to read your TSH
High TSH usually means underactive thyroid (hypothyroidism) because the pituitary is shouting louder at a thyroid that is not responding. Low TSH means overactive thyroid (hyperthyroidism).
When to test
Annually if you are on thyroid medication. Every 5 years after age 35 as a screening. Immediately if you develop unexplained fatigue, weight changes, or mood changes. During pregnancy and when trying to conceive.