Brief Answer:
Hypothyroid symptoms

Detailed Answer:
The clinical manifestations of hypothyroidism are highly variable, depending upon the age at onset and the duration and severity of thyroid hormone deficiency. Common symptoms of thyroid hormone deficiency include fatigue, cold intolerance, weight gain, constipation, dry skin, muscle aches and menstrual irregularities. Physical examination findings may include neck swelling ('goiter') , slower pulse, rise in blood pressure and a delayed relaxation phase of the deep tendon reflexes.
To elaborate, the symptoms of hypothyroidism vary widely; some people have no symptoms while others have dramatic symptoms or, rarely, life-threatening symptoms. The symptoms of hypothyroidism are notorious for being nonspecific and for mimicking many of the normal changes of aging. Usually, symptoms are milder when hypothyroidism develops gradually. Symptoms, when caused by hypothyroidism, generally are related to the degree of hypothyroidism. Many patients with mild hypothyroidism are identified on screening tests for potential hypothyroid symptoms, but have few or no symptoms that ultimately are attributed to hypothyroidism or respond to treatment of hypothyroidism. In contrast, patients with moderate to severe hypothyroidism are usually symptomatic and improve significantly with thyroid hormone replacement.

General symptoms — Thyroid hormone normally stimulates the metabolism, and most of the symptoms of hypothyroidism reflect slowing of metabolic processes. General symptoms may include fatigue, sluggishness, weight gain, and intolerance of cold temperatures.

Skin — Hypothyroidism can decrease sweating. The skin may become dry and thick. The hair may become coarse or thin, eyebrows may disappear, and nails may become brittle.

Eyes — Hypothyroidism can lead to mild swelling around the eyes. People who develop hypothyroidism after treatment for Graves' disease may retain some of the eye symptoms of Graves' disease, including protrusion of the eyes, the appearance of staring, and impaired movement of the eyes.

Cardiovascular system — Hypothyroidism slows the heart rate and weakens the heart's contractions, decreasing its overall function. Related symptoms may include fatigue and shortness of breath with exercise. These symptoms may be more severe in people who also have heart disease. In addition, hypothyroidism can cause mild high blood pressure and raise blood levels of cholesterol.

Respiratory system — Hypothyroidism weakens the respiratory muscles and decreases lung function. Symptoms can include fatigue, shortness of breath with exercise, and decreased ability to exercise. Hypothyroidism can also lead to swelling of the tongue, hoarse voice, and sleep apnea. Sleep apnea is a condition in which there is intermittent blockage of the airway while sleeping, causing fitful sleep and daytime sleepiness.

Gastrointestinal system — Hypothyroidism slows the actions of the digestive tract, causing constipation. Rarely, the digestive tract may stop moving entirely.

Reproductive system — Women with hypothyroidism often have menstrual cycle irregularities, ranging from absent or infrequent periods to very frequent and heavy periods. The menstrual irregularities can make it difficult to become pregnant, and pregnant women with hypothyroidism have an increased risk for miscarriage during early pregnancy. Treatment of hypothyroidism can decrease these risks.

Myxedema coma — In people with severe hypothyroidism, trauma, infection, exposure to the cold, and certain medications can rarely trigger a life-threatening condition called myxedema coma, which causes a loss of consciousness and hypothermia (low body temperature).

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