What causes a low Thyroid-Stimulating Hormone (TSH)?

Q: What causes a low Thyroid-Stimulating Hormone (TSH)?

Common causes of a low Thyroid-Stimulating Hormone (TSH): Primary hyperthyroidism (Graves); Excess thyroid hormone replacement; Central hypothyroidism.

Normal range 0.4-4 mIU/L. Specimen: Serum. See the full Thyroid-Stimulating Hormone (TSH) reference page for critical values and nursing considerations.

Below the range

Common causes of a low Thyroid-Stimulating Hormone (TSH)

Primary hyperthyroidism (Graves)
Excess thyroid hormone replacement
Central hypothyroidism

Looking for the other direction? See what causes a high Thyroid-Stimulating Hormone (TSH).

What is the normal range for Thyroid-Stimulating Hormone (TSH)?

The standard teaching reference range for Thyroid-Stimulating Hormone (TSH) is 0.4-4 mIU/L. This value is measured in serum.

Thyroid-Stimulating Hormone (TSH) reference range and specimen details
Specimen	Serum
Conventional range	0.4-4 mIU/L
SI range	0.4-4 mIU/L
Panel	Thyroid Function

Full details, including nursing considerations, on the Thyroid-Stimulating Hormone (TSH) normal range page. Reference ranges vary by laboratory, method, age, sex, and population - always use the range printed on the actual result.

Same panel

More Thyroid Function tests

Free Thyroxine (Free T4)0.8-1.8 ng/dL Free Triiodothyronine (Free T3)2.3-4.2 pg/mL Thyroid Peroxidase Antibody (TPO Ab)< 35 (negative) IU/mL Total Thyroxine (Total T4)5-12 µg/dL Total Triiodothyronine (Total T3)80-200 ng/dL