Diagnostic Approach for Unintentional Weight Loss, Palpitations, and Heat Intolerance

Initial Evaluation

The American Heart Association recommends performing a 12-lead ECG to assess for tachycardia, arrhythmias, or other cardiac abnormalities that may be related to thyroid dysfunction or other causes in patients with unintentional weight loss, palpitations, and heat intolerance 1
The American College of Cardiology suggests checking vital signs with particular attention to heart rate, blood pressure, and temperature to evaluate for tachycardia and hypertension in patients presenting with these symptoms 2
A physical examination should focus on thyroid gland assessment, cardiac examination, skin assessment, eye examination, and tremor assessment, as recommended by the Journal for ImmunoTherapy of Cancer 3

The American College of Cardiology recommends a 48-hour ambulatory ECG monitoring for persistent palpitations to identify potential arrhythmias 1
Echocardiography may be considered to exclude structural heart disease if palpitations are frequent or sustained, as suggested by the American College of Cardiology 1
For less frequent episodes, an event recorder or implantable loop recorder may be considered if symptoms persist without diagnosis, according to the American College of Cardiology 1

The American Heart Association recommends screening for substance use that could cause similar symptoms, such as stimulants or drugs, in patients with unintentional weight loss, palpitations, and heat intolerance 2
Evaluation for pheochromocytoma with 24-hour urinary fractionated metanephrines or plasma metanephrines may be considered if hypertension is present, as suggested by the American Heart Association 2
The American College of Cardiology recommends management of cardiac arrhythmias according to guidelines for the specific arrhythmia identified, with consideration of vagal maneuvers, beta-blockers, or referral for electrophysiology evaluation for supraventricular tachycardia 4
The Journal of the American College of Cardiology suggests considering beta-blockers for symptom control while awaiting definitive treatment for hyperthyroidism 5

Referral to endocrinology is recommended if hyperthyroidism is confirmed for specialized management, as suggested by the Journal for ImmunoTherapy of Cancer 3
Referral to cardiology/electrophysiology is recommended if complex arrhythmias are detected, palpitations are associated with syncope or pre-syncope, or structural heart disease is identified, according to the American College of Cardiology 1