What is the normal range for TSH levels?

The normal range for Thyroid-Stimulating Hormone (TSH) levels is widely accepted to be between 0.4 and 4.0 micro-international units per milliliter (µIU/mL). This range is used by many laboratories and medical guidelines to assess thyroid function and to diagnose potential thyroid disorders.

TSH is produced by the pituitary gland and regulates the production of hormones by the thyroid gland. Levels outside of this range might indicate hypothyroidism or hyperthyroidism, depending on whether they are elevated or low, respectively. Clinicians rely on this range when evaluating patients with symptoms suggestive of thyroid dysfunction or when monitoring patients with known thyroid conditions.

The other ranges provided in the options do not align with the consensus and may lead to misinterpretation of thyroid function tests, which is why the 0.4 to 4.0 µIU/mL range is critical for accurate assessment and diagnosis.