Diagnosis of thyroid disorders begins with a physical examination by a physician, paying careful attention to a patient’s head and neck. A physician typically also compiles a medical history of the patient, which may include questions about symptoms and whether there is a family history of similar symptoms or thyroid disorders.

Tests that may be performed to help diagnosis thyroid disorders that may affect the heart include:

• Thyroid blood tests. These lab tests measure levels of thyroid hormones as well as thyroid stimulating hormone (TSH), which is produced by the pituitary gland. Testing may be performed to help diagnose some types of thyroid disorders, as well as to monitor patients being treated for thyroid disorders.
  
  
• Thyroid imaging tests. Procedures such as a thyroid scan may be used to identify whether inflammation (thyroiditis) or enlargement (goiter) of the gland exists. They may also identify the presence of thyroid nodules or cancer. A thyroid scan may be performed with or without the use of radioactive iodine.
  
  
• Biopsy. A sample of tissue from the thyroid gland, usually taken with a needle, may be analyzed by a laboratory.
  
  
• Chest x-ray. This painless imaging test can help a physician determine whether a patient has an enlarged heart, which may be a sign of a thyroid disorder.
  
  
• Electrocardiogram (EKG or ECG). If a patient experiences heart-related symptoms, such as palpitations or chest pain, an EKG will likely be performed. The EKG is a recording of the heart’s electrical activity. It may be used to identify heart irregularities, disease or damage by measuring the heart’s rhythms and electrical impulses.

Patients suspected of having a thyroid disorder may be referred to an endocrinologist (physician specializing in disorders of the endocrine system).