ABFM Board Review - Heart Disease Focus 2025 Study Questions & Certified Answers A+ Family Medicine Prep A 65-year-old female who has heart failure with an ejection fraction of 35% is found to have a TSH level of 13.8 U/mL (N 0.3-4.82). Her T3 and T4 levels are normal, and her thyroid gland is normal to palpation. You check her levels again in 2 months and they are unchanged. You advise her that hypothyroidism decreases her metabolic rate, which reduces the stress on her heart hypothyroidism is detrimental to her heart only if she develops hypothyroid symptoms subclinical hypothyroidism has negative effects on heart failure and treatment should be considered treatment of subclinical hypothyroidism would raise her LDL-cholesterol level C Clinical hypothyroidism has long been associated with cardiac dysfunction. It has also been shown that subclinical hypothyroidism (TSH >4 U/mL with normal or borderline low thyroid hormone levels) can cause left ventricular systolic and diastolic dysfunction, which improves with thyroid replacement therapy. Patients with overt or subclinical hypothyroidism should be treated with levothyroxine to improve their cardiovascular function and decrease the potential risk of heart failure. Thyroxine in excess can exacerbate coronary artery disease, and should be started at low