TSH

Thyroid-stimulating hormone

Group
Thyroid
Sample
Blood · morning advised
unit
mIU/L
TSHThyroid-stimulating hormone mIU/L About 0.4–4.0 mIU/L (lab-specific)

Source: Laboratory reference ranges; American Thyroid Association

What does it measure?

The pituitary hormone that drives the thyroid. TSH rises when thyroid hormones fall and falls when they rise.

Relationship to nutrition

TSH reflects thyroid function and medication dose more than diet. Adequate iodine (iodised salt, dairy, fish), selenium and iron matter. Taking thyroid medication with coffee, calcium or iron can reduce absorption.

Before the test

  • If you take thyroid medication, ask your doctor when to take it on test day.
  • Biotin supplements can affect some assays; you may be asked to stop them a few days before.

This page is general information. Reference ranges vary by laboratory, age, sex and pregnancy; the range on your report is the one that applies. Diagnosis and treatment are carried out by your doctor. No values are entered on this page and no data is sent to the server.