Hypothyroidism (underactive thyroid)

Hypothyroidism is a condition in which your thyroid gland doesn’t produce enough of certain crucial hormones.

Hypothyroidism may not cause noticeable symptoms in the early stages. Over time, untreated hypothyroidism can cause a number of health problems, such as obesity, joint pain, infertility and heart disease.

Accurate thyroid function tests are available to diagnose hypothyroidism. Treatment with synthetic thyroid hormone is usually simple, safe and effective once you and your doctor find the right dose for you.

The signs and symptoms of hypothyroidism vary, depending on the severity of the hormone deficiency. Problems tend to develop slowly, often over a number of years.

At first, you may barely notice the symptoms of hypothyroidism, such as fatigue and weight gain. Or you may simply attribute them to getting older. But as your metabolism continues to slow, you may develop more-obvious problems.
Hypothyroidism signs and symptoms may include:
1. Fatigue
2. Increased sensitivity to cold
3. Constipation
4. Dry skin
5. Weight gain
6. Puffy face
7. Hoarseness
8. Muscle weakness
9. Elevated blood cholesterol level
10. Muscle aches, tenderness and stiffness
11. Pain, stiffness or swelling in your joints
12. Heavier than normal or irregular menstrual periods
13. Thinning hair
14. Slowed heart rate
15. Depression
16. Impaired memory
17. Enlarged thyroid gland (goiter)

Risk factors
Although anyone can develop hypothyroidism, you’re at an increased risk if you:
1. Are a woman
2. Are older than 60
3. Have a family history of thyroid disease
4. Have an autoimmune disease, such as type1 diabetes or celiac disease
5. Have been treated with radioactive iodine or anti-thyroid medications
6. Received radiation to your neck or upper chest
7. Have had thyroid surgery (partial thyroidectomy)
8. Have been pregnant or delivered a baby within the past six months

Untreated hypothyroidism can lead to a number of health problems:
1. Goiter. Constant stimulation of your thyroid to release more hormones may cause the gland to become larger — a condition known as a goiter. Although generally not uncomfortable, a large goiter can affect your appearance and may interfere with swallowing or breathing.
2. Heart problems. Hypothyroidism may also be associated with an increased risk of heart disease and heart failure, primarily because high levels of low-density lipoprotein (LDL) cholesterol — the “bad” cholesterol — can occur in people with an underactive thyroid.
3. Mental health issues. Depression may occur early in hypothyroidism and may become more severe over time. Hypothyroidism can also cause slowed mental functioning.
4. Peripheral neuropathy. Long-term uncontrolled hypothyroidism can cause damage to your peripheral nerves. These are the nerves that carry information from your brain and spinal cord to the rest of your body — for example, your arms and legs. Peripheral neuropathy may cause pain, numbness and tingling in affected areas.
5. Myxedema. This rare, life-threatening condition is the result of long-term, undiagnosed hypothyroidism. Its signs and symptoms include intense cold intolerance and drowsiness followed by profound lethargy and unconsciousness.
6. Myxedema coma. A myxedema coma may be triggered by sedatives, infection or other stress on your body. If you have signs or symptoms of myxedema, you need immediate emergency medical treatment.
7. Infertility. Low levels of thyroid hormone can interfere with ovulation, which impairs fertility. In addition, some of the causes of hypothyroidism — such as autoimmune disorder — can also impair fertility.
8. Birth defects. Babies born to women with untreated thyroid disease may have a higher risk of birth defects compared to babies born to healthy mothers. These children are also more prone to serious intellectual and developmental problems.
9. Physical and Mental Development Problems: Infants with untreated hypothyroidism present at birth are at risk of serious problems with both physical and mental development. But if this condition is diagnosed within the first few months of life, the chances of normal development are excellent.