The normal range for TSH is approximately?

The normal range for TSH is approximately?

• A. 0.1-0.3 mIU/L
• B. 1.0-3.0 mIU/L
• C. Approximately 0.4-4.0 mIU/L
• D. 5.0-6.0 mIU/L

Answer: (C)

TSH level interpretation hinges on the pituitary’s feedback response to circulating thyroid hormones. In adults, the typical reference range is about 0.4 to 4.0 mIU/L. Values below this range point toward hyperthyroidism, while values above point toward hypothyroidism, though exact cutoffs can vary between labs and patient factors. Some labs use a narrower range like 0.5–3.5 or widen it toward 5.0, but the commonly cited general range is 0.4–4.0. Special populations, such as pregnant individuals, have different targets, and assay differences can shift numbers slightly. Ranges like 0.1–0.3 or 5.0–6.0 would be outside normal for a nonpregnant adult.

TSH level interpretation hinges on the pituitary’s feedback response to circulating thyroid hormones. In adults, the typical reference range is about 0.4 to 4.0 mIU/L. Values below this range point toward hyperthyroidism, while values above point toward hypothyroidism, though exact cutoffs can vary between labs and patient factors. Some labs use a narrower range like 0.5–3.5 or widen it toward 5.0, but the commonly cited general range is 0.4–4.0. Special populations, such as pregnant individuals, have different targets, and assay differences can shift numbers slightly. Ranges like 0.1–0.3 or 5.0–6.0 would be outside normal for a nonpregnant adult.