The thyroid gland produces the hormones triiodothyronine (T3) and thyroxine (T4), which help regulate metabolism. Metabolism can affect your weight, body temperature, and energy. An under or overactive thyroid can alter your heart rhythms, which may lead to heart failure.
Hypothyroidism: An underactive thyroid gland slows down the metabolism, which can lead to weight gain and fatigue. Other symptoms of hypothyroidism include:
- Sensitivity to cold
- Change in menstrual periods
- Muscle pain/ weakness
- Joint pain/ stiffness
- Dry skin and hair
- Increased cholesterol levels
- Confusion and memory problems
Hypothyroidism is commonly caused by Hashimoto’s disease, an autoimmune disease in which cells in the thyroid are mistakenly attacked by your body’s immune system. An underactive thyroid can lead to heart problems, mental health problems, nerve damage, infertility, and other complications.
Hyperthyroidism: An overactive thyroid gland produces excessive levels of T3 and T4 hormones. This can produce symptoms such as:
- Weight loss
- Rapid heartbeat (tachycardia)
- Nervousness or anxiety
- Tremor (trembling in the hands and fingers)
- Increased appetite
- Changes in menstrual cycles
- Sensitivity to heat and excessive sweating
- Sleep problems
- Bulging eyes (common in Grave’s disease)
- Hair loss, or thinning of hair
Hyperthyroidism can lead to complications such as heart problems, brittle bones, eye problems (especially common with Grave’s disease), and thyrotoxic crisis. This last condition results in a sudden increase in the severity of your symptoms and delirium. A thyrotoxic crisis is a medical emergency and requires immediate care.