What is the normal range for TSH, and what does a high TSH indicate?

What is the normal range for TSH, and what does a high TSH indicate?

• A. 1–5 mIU/L; elevated suggests hypothyroidism
• B. 0.4–4.0 mIU/L; elevated suggests hypothyroidism.
• C. 0.1–0.5 mIU/L; elevated suggests diabetes.
• D. 2–6 mIU/L; elevated suggests anemia

Answer: (B)

TSH is the pituitary signal that tells the thyroid to make hormones. The typical normal range is about 0.4–4.0 mIU/L. A high TSH means the thyroid isn’t making enough hormones, so the pituitary raises TSH to stimulate it—this points to hypothyroidism. If TSH is high with normal free T4, that’s subclinical hypothyroidism; if free T4 is low, it’s overt hypothyroidism. The other options give ranges that aren’t the standard reference, and they incorrectly tie high TSH to conditions like diabetes or anemia, which aren’t related to TSH.

TSH is the pituitary signal that tells the thyroid to make hormones. The typical normal range is about 0.4–4.0 mIU/L. A high TSH means the thyroid isn’t making enough hormones, so the pituitary raises TSH to stimulate it—this points to hypothyroidism. If TSH is high with normal free T4, that’s subclinical hypothyroidism; if free T4 is low, it’s overt hypothyroidism. The other options give ranges that aren’t the standard reference, and they incorrectly tie high TSH to conditions like diabetes or anemia, which aren’t related to TSH.