The signs and symptoms of thyroid disorders can vary significantly from person to person. They may also vary depending on the type of thyroid disorder present. For example, hypothyroidism commonly includes symptoms such as fatigue, a slow heart rate, weight gain, feeling cold, muscle cramps, heavy menstrual flow and constipation. In contrast, hyperthyroidism may include symptoms such as a fast heart rate, weight loss, increased perspiration, muscle weakness, decreased menstrual flow and increased frequency of bowel movements.

In the case of goiter, thyroid nodules or thyroid cancer, symptoms may include a lump at the front of the neck, swollen lymph nodes, difficulty swallowing or breathing, hoarseness, and pain in the throat or neck. However, in many patients, these thyroid disorders do not cause symptoms. Symptoms of thyroiditis can vary, depending on the type of thyroiditis involved. For example, Hashimoto’s thyroiditis involves symptoms that are similar to hypothyroidism.

Thyroid disorders may affect the heart, causing problems such as high blood pressure and high cholesterol. In some cases, atrial fibrillation may occur. Symptoms of heart involvement associated with thyroid disorders may vary, depending on the type of thyroid disorder present.

The most common cardiac symptoms of hypothyroidism include:

• Bradycardia (slow heart rate). Thyroid hormones help regulate the heart rate. When there is not enough hormone production the heart can beat 10 to 20 beats slower than normal.
  
  
• Shortness of breath during physical exertion. When this symptom occurs in patients with heart disease, it may indicate skeletal muscle weakening or a worsening of heart failure.
  
  
• Diastolic hypertension. Even though hypothyroidism slows a person’s metabolism, it can cause high diastolic blood pressure due to the stiffening of the arteries.
  
  
• Onset or worsening of heart failure. Hypothyroidism can cause individuals with mild heart disease to have heart failure for the first time. In people with well-controlled heart failure, it can cause it to become worse.
  
  
• Worsening of coronary artery disease (CAD). Hypothyroidism can cause patients with angina (cardiac chest pain) to have increased levels of LDL cholesterol and C-reactive proteins. These elements can accelerate underlying CAD.

The most common cardiac symptoms of hyperthyroidism include:

• Tachycardia (fast heart rate). With mild exertion, people with hyperthyroidism can have an increased heart rate at rest and during mild exertion. It can also produce a number of other arrhythmias, including atrial fibrillation and premature ventricular contraction (PVC).
  
  
• Angina. This may occur after hyperthyroidism develops, or if it already exists in patients with heart disease, it may be worsened with hyperthyroidism. Individuals with CAD have a risk of experiencing increased chest pain or a heart attack.
  
  
• Shortness of breath. As with hypothyroidism, difficulty breathing can be a symptom of muscle weakness or a worsening of heart failure.
  
  
• Systolic hypertension. Stronger heart contractions cause the systolic blood pressure to increase, although relaxed blood vessels help reduce diastolic blood pressure.

People who suspect they may have a thyroid disorder should consult their physician. Anyone experiencing the cardiac symptoms mentioned above should seek immediate medical attention.

Some patients have no symptoms of a thyroid disorder. The American Thyroid Association recommends that all people be routinely screened for thyroid dysfunction beginning at the age of 35 and every five years thereafter.