Hypothyroidism — CCFP MCQ

Instant feedback + full explanation. One question, done properly.

ModerateChronic disease managementHypothyroidismCCFP

A 56-year-old woman presents with a 3-month history of fatigue, constipation, and cold intolerance. Physical examination is unremarkable. Investigations reveal TSH 18 mIU/L (reference 0.5–5.0) and free T4 below the reference range. She denies chest pain and has no known history of coronary disease. What is the most likely diagnosis?

Educational content. Not a substitute for clinical judgement or local policy.

Reveal the answer and explanation

Correct answer: D — Overt hypothyroidism

Explanation lettering: B = shown as A · C = shown as B · D = shown as C · E = shown as D · A = shown as E

Overt hypothyroidism is diagnosed by the combination of elevated serum TSH and low free T4, reflecting primary thyroid gland failure with intact pituitary feedback. This patient's TSH of 18 mIU/L is significantly elevated, and free T4 is frankly low—the hallmark biochemical pattern. Her classic symptoms (fatigue, constipation, cold intolerance) and age are consistent with autoimmune thyroiditis. Subclinical hypothyroidism (distractor A) requires normal T4/T3 but TSH 4–10 mIU/L; she has low free T4, making this overt disease. Euthyroid sick syndrome (D) presents with low TSH, not elevated. Central diabetes insipidus (B) is unrelated to thyroid function. Iron deficiency (C) causes fatigue but does not suppress free T4 or elevate TSH.

Reference: College of Family Physicians of Canada. Central hypothyroidism. Canadian Family Physician 2011;57(6):677. https://www.cfp.ca/content/57/6/677