TSH

Understanding the marker

TSH is made by the pituitary gland and signals the thyroid to produce hormones. It is often measured first when assessing thyroid function.

Interpret it with symptoms and, when indicated, free T4. Acute illness, medicines and some supplements can affect results. TSH alone is insufficient when pituitary disease is suspected.

What does high TSH mean?

High TSH can mean the pituitary is sending a stronger signal to the thyroid. Free T4, symptoms, any treatment and sometimes a repeat result help determine whether thyroid hormone production is insufficient.

What does low TSH mean?

Low TSH can occur when the thyroid hormone level is high or as an effect of treatment. Free T4, sometimes free T3, and symptoms help determine what the pattern means.