Lab marker · High

High Thyroid Stimulating Hormone (TSH): what it means

A Thyroid Stimulating Hormone (TSH) result above the normal range is considered high. Here is what a raised Thyroid Stimulating Hormone (TSH) can point to, and when it is worth discussing with a doctor.

Reference range: 0.4–4.0 mIU/L (most labs); pregnancy and treatment targets differ

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What a high Thyroid Stimulating Hormone (TSH) can mean

  • Primary hypothyroidism — under-active thyroid (Hashimoto's autoimmune thyroiditis is the most common cause in iodine-replete populations).
  • Sub-clinical hypothyroidism — TSH 4–10 with normal free T4, often early Hashimoto's.
  • Recovery from non-thyroidal illness — transient elevation as the body re-balances.
  • Some medications — amiodarone, lithium.

When to discuss with a doctor

TSH outside the 0.4–4.0 mIU/L band — especially if paired with fatigue, weight change, palpitations or mood changes — warrants follow-up labs (free T4, sometimes free T3 and thyroid antibodies) and a clinician visit. In pregnancy, target ranges are tighter (typically <2.5 mIU/L in the first trimester).

Conditions this can relate to

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Mediora.AI is informational - interpretation, not a diagnosis. A single out-of-range value is common and often benign; always discuss decisions with your doctor.