Difference Between Underactive and Overactive Thyroid

The thyroid gland, or simply the thyroid, is an endocrine gland in the neck, consisting of two lobes connected by an isthmus. It is found at the front of the neck, below the Adam’s apple. The thyroid gland secretes thyroid hormones, which mainly influence the metabolic rate and protein synthesis.

The hormones also have many other effects including those on development. The thyroid hormones triiodothyronine (T3) and thyroxine (T4) are created from iodine and tyrosine. The thyroid also produces the hormone calcitonin, which plays a role in calcium homeostasis.

Hormonal output from the thyroid is regulated by thyroid-stimulating hormone (TSH) secreted from the anterior pituitary gland, which itself is regulated by thyrotropin-releasing hormone (TRH) produced by the hypothalamus.
The thyroid may be affected by several diseases such as hyperthyroidism and hypothyroidism, among others.

Following is a list of symptoms from an overactive and underactive thyroid. Try not to confuse the similarity of the terms “hypo” and “hyper”, one meaning too little and the other too much, respectively. As help in remembering these, try to think of a hyperactive person, as they are always energetic and active.

Keep in mind that some of the listed symptoms might be the same for both conditions. Also, note that this is neither a medical advice nor a substitute for professional diagnosis.

If you have any of the listed symptoms, you need to get a medical checkup as soon as possible and your doctor can measure the actual levels of thyroid hormones, as well as any other relevant tests you might need.

Hyperthyroidism (overactive thyroid):
Hair loss. Sleeping disorder. Warm, moist palms. Rapid heartbeat. Sweating. Weight loss. Frequent bowel movement. Tremors. Bulging eyes (Graves Disease). Enlarged thyroid (goiter). Soft / splitting nails. Heat intolerance. Irritability. Muscle weakness. Nervousness. Irregular menstrual periods.

Hypothyroidism (underactive thyroid):
Dry, coarse hair. Loss of eyebrow hair. Puffy face. Enlarged thyroid (goiter). Slow heartbeat. Weight gain. Constipation. Nails splitting. Arthritis risk increased. Cold intolerance. Depression / moodiness. Dry skin. Fatigue. Forgetfulness. Infertility. Heavy and painful menstrual periods. Muscle aches. Moodiness.