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An overactive thyroid gland is typically removed if it becomes unresponsive to prescribed hormone suppressants. If left untreated, it can lead to heart attack or stroke. After the removal, patients will experience long-term side effects that will require management over the rest of their lifetimes.


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Hypothyroidism, or a chronically under-active thyroid, is the most common side effect of thyroid removal surgery. During surgery, endocrinologists specifically take out more of the gland than is necessary to prevent it from becoming overactive again. However, in many patients, the gland never grows back to its normal size, causing under-activity for life.

Weight Gain

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Weight gain of up to 20 Ibs. after the surgery is a common side effect. One side effect of hyperthyroidism is a very high metabolism. After surgery, metabolic rate, and the number of calories that should be consumed drops more rapidly than most patients can adjust to, which causes weight gain.


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As thyroid activity drops from an abnormally high level to normal and subnormal levels, patients will often experience depression or low mood as a side effect due to the shift in brain chemical production.

Intolerance to Cold

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Hyperthyroid patients become intolerant to heat as their metabolism raises their body temperature. However, after the thyroid is removed and metabolic rate drops, patients experience cold intolerance as their basal body temperature decreases to around 97.8 degrees F.


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Post-thyroid removal surgery, most patients experience chronic constipation as a side effect. The rate of digestion is controlled by the thyroid, and as thyroid hormone in the blood decreases, so does the speed at which food digests, causing less frequent bowel movements.