Sections View Full Chapter Figures Tables Videos Annotate Full Chapter Figures Tables Videos Supplementary Content +++ KEY FEATURES +++ ESSENTIALS OF DIAGNOSIS ++ Thyroid-stimulating hormone (TSH) levels above normal range (primary hypothyroidism). Low free T4 or low free thyroxin index (FTI) +++ GENERAL CONSIDERATIONS ++ Hypothyroidism is caused by thyroid hormone insufficiency Myxedema refers to profound hypothyroidism resulting in severe hypothermia, hypoventilation, and hypotension with signs of neurologic impairment Hypothyroidism accelerates atherosclerosis, but angina and myocardial infarction are rare until thyroid hormone is replaced because of the reduced metabolic demands of the hypothyroid state Hypothyroidism can be caused by: – Thyroid disease (eg, Hashimoto’s thyroiditis) – Congenital abnormalities – Iodine deficiency – Drugs such as lithium +++ CLINICAL PRESENTATION +++ SYMPTOMS AND SIGNS ++ Weight gain, weakness, lethargy, cold intolerance, dry skin, and coarse hair Amenorrhea or impotence Dyspnea on exertion +++ PHYSICAL EXAM FINDINGS ++ Bradycardia Mild diastolic hypertension Pleural effusions Hypothermia Goiter in some Distant heart sounds Delayed reflexes in the return phase Nonpitting edema (myxedema) +++ DIFFERENTIAL DIAGNOSIS ++ Congestive heart failure due to other causes Other causes of effusions and edema Hyperlipidemia and atherosclerosis without hypothyroidism Amiodarone toxicity +++ DIAGNOSTIC EVALUATION +++ LABORATORY TESTS ++ Elevated TSH, reduced T4, T3, and FTI Hyperlipidemia is common Anemia Elevated antithyroid antibodies in Hashimoto’s disease +++ ELECTROCARDIOGRAPHY ++ Sinus bradycardia Low or flattened T waves Increased PR and QT intervals +++ IMAGING STUDIES ++ Echocardiography: – Pericardial effusion common, but signs of tamponade unusual – Reduced cardiac performance +++ DIAGNOSTIC PROCEDURES ++ Coronary angiography may be necessary +++ TREATMENT +++ CARDIOLOGY REFERRAL ++ Suspected cardiac disease +++ HOSPITALIZATION CRITERIA ++ Heart failure symptoms and signs +++ MEDICATIONS ++ Thyroid hormone replacement, which must be given slowly to older patients or those suspected of having coronary artery disease, to prevent exacerbation of angina and precipitation of myocardial infarction +++ THERAPEUTIC PROCEDURES ++ Coronary revascularization should be considered before thyroid replacement therapy in high-risk patients +++ MONITORING ++ ECG monitoring in hospital as appropriate TSH levels during treatment +++ DIET AND ACTIVITY ++ Low-fat diet Reduced activity until condition improves +++ ONGOING MANAGEMENT +++ HOSPITAL DISCHARGE CRITERIA ++ Resolution of problem +++ FOLLOW-UP ++ As appropriate for condition +++ COMPLICATIONS ++ Heart failure Angina or myocardial infarction during treatment +++... Your Access profile is currently affiliated with [InstitutionA] and is in the process of switching affiliations to [InstitutionB]. Please select how you would like to proceed. Keep the current affiliation with [InstitutionA] and continue with the Access profile sign in process Switch affiliation to [InstitutionB] and continue with the Access profile sign in process Get Free Access Through Your Institution Learn how to see if your library subscribes to McGraw Hill Medical products. Subscribe: Institutional or Individual Sign In Error: Incorrect UserName or Password Username Error: Please enter User Name Password Error: Please enter Password Sign in Forgot Password? Forgot Username? Download the Access App: iOS | Android Sign in via OpenAthens Sign in via Shibboleth You already have access! Please proceed to your institution's subscription. Create a free profile for additional features.