Endocrine Abstracts

Introduction: We report a case of severe thyrotoxic cardiomyopathy, a potentially life threatening complication of thyrotoxicosis.

Case report: A female, age 47, usually fit and well, presented to the GP with 4 week history of feeling generally unwell, intermittent palpitations and right leg swelling. Ultrasound ruled out a DVT. She developed shortness of breath, heat intolerance, tremor, weight loss, generalized body swelling. She noticed change in her voice and neck swelling.

On admission she had tremor, goitre, hypertension (BP 194/88 mmHg), tachycardia (HR 116). U&E and LFT were normal except for raised ALP of 196 IU/l. TFT showed TSH <0.01 mU/l, FT₄ 84.1 pmol/l, TPO antibodies 405 IU/ml.

She was started on carbimazole 20 mg OD, propranolol 40 mg OD, hydrocortisone and furosemide. After endocrine review, carbimazole was increased to 60 mg OD, furosemide doubled to 80 mg OD and steroid was discontinued. Echocardiogram confirmed severe cardiomyopathy and pulmonary hypertension. Cardiology reviewed to rule out other causes of congestive heart failure. She responded to treatment and repeat TFT 7 days later showed TSH <0.02 mU/l, FT₄ 23.8 pmol/l, FT₃ 4.2 pmol/l.

Discussion: Thyrotoxicosis effects peripheral circulation (increased circulatory volume, reduced pre-load, pulmonary hypertension) and has direct cardiac effects including arrhythmias, alteration of myocardial contractility, left ventricular hypertrophy and cardiomyopathy.

Cardiac failure may be rate related, secondary to volume overload or left ventricular impairment. Prevalence varies from 12 to 68%. Although usually associated with underlying heart disease, it can occur in young people even in the absence of heart disease.

Dilated cardiomyopathy is reported in 1%. The mechanisms are poorly understood. It can be irreversible in up to 1/3 of patients. Risk factors include older age, male sex and duration of thyrotoxicosis. Initial management with β-blockers for rate control, diuretics and anti-thyroid medication should be followed by definitive management of thyrotoxicosis.

As a potentially reversible cause of cardiomyopathy, hyperthyroidism should be excluded in all patients.