Hi there! Thank you for your question. Increase heart rate also known as tachycardia is when heart rate exceed 100 beats per minute. This symptom could be caused by many factors. Yes, thyroid problems can also cause fast heart rate. Other factors include :

1. Heart problems such as atrial fibrillation (a condition where the heart beats fast and irregularly.
2. Blood problems such as anaemia. Anaemia is a condition where there is low haemoglobin levels ( a protein responsible to transport oxygen throughout the body)
3. Psychiatric issues such as anxiety and panic attacks
4. Lifestyle and smoking.

Other investigations such as an ECG will be done to rule out other causes.
As for your question, thyroid problems more specifically hyperthyroid can cause increase heart rate. Hyperthyroid is when the thyroid gland (an organ located at the neck) is producing excessive amount of hormones. These hormones are the T3 and T4 hormone.

Thyroid hormones are responsible for your metabolism. This in return will cause the increase heart rate. Other symptoms/signs to suggest hyperthyroidism includes tremor, warm intolerance, loss of hair, muscle weakness, weight loss, hypertension, neck swelling, leg swelling, eye swelling and nail changes (clubbing).

As to confirm hyperthyroid, a thyroid hormone test must be done. This test usually test for 3 hormones, thyroid stimulating hormone (TSH), T3 and T4. Once hyperthyroid is diagnosed, the cause of the hyperthyroidism needs to be established. There are many causes of hyperthyroidism, most are benign but some can be malignant. Further investigations will be done depending the probable cause suspected by the doctor.

This is to ensure more targeted management and to treat the underlying cause. As for the management of the hyperthyroid, drugs, radioactive iodine and surgery are the available treatments.
So to answer your question, yes, a thyroid function should be done as well as other investigations to rule out other causes.

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