What Are Normal TSH Levels?

Standard normal TSH is 0.4–4.0 mIU/L.

Standard Ranges

  • Adults: 0.4–4.0
  • Pregnancy T1: 0.1–2.5
  • Elderly: may be higher

Optimal vs Normal

  • Some prefer 0.5–2.5
  • TSH rises with age

Factors Affecting TSH

  • Time of day
  • Stress
  • Biotin supplements
  • Medications
Source: American Thyroid Association, NLM MedlinePlus.

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