Many of the symptoms of hypothyroidism also occur with a number of other conditions and problems.

Primary hypothyroidism affects the whole body and may cause a variety of symptoms. The body's normal rate of functioning slows, leading to mental and physical sluggishness. Symptoms may vary from mild to severe. The most severe form is called myxedema coma and is a medical emergency.

Early symptoms:

• Cold intolerance
• Constipation
• Depression
• Fatigue
• Muscle or joint pain
• Paleness
• Thin, brittle fingernails
• Thin, brittle hair
• Weakness
• Weight gain

Late symptoms:

• Decreased sense of taste and smell
• Dry flaky skin
• Hoarseness
• Menstrual disorders
• Puffy face, hands, and feet
• Slow speech
• Thickening of the skin
• Thinning of eyebrows

Physical examination may reveal a smaller than normal gland. However, sometimes the gland is normal in size or even enlarged (goiter). Other signs include:

• Coarse facial features
• Firm swelling of the arms and legs
• Loss of the edges of the eyebrows
• Low blood pressure
• Low temperature
• Pale, yellow, and dry skin
• Slow heart rate
• Slow muscle relaxation when reflexes are tested
• Thin, brittle hair

A chest x-ray sometimes shows an enlarged heart.

Laboratory tests to determine thyroid function include:

• Free T4 or free thyroxine index (low)
• Free T4 test (low)
• Serum thyroid stimulating hormone (TSH) (high)

Other problems found on lab tests may include:

• Anemia on a complete blood count (CBC)
• Increased cholesterol levels
• Increased liver enzymes
• Increased serum prolactin
• Low serum sodium