With an underactive thyroid, or hypothyroidism, the thyroid does not produce as many hormones as usual. Several symptoms can occur with an underactive thyroid. The MayoClinic.com noted that these symptoms can vary, as they depend on how severe the hormone deficiency is.
The first symptoms of hypothyroidism, such as feeling sluggish or fatigued, may not be very noticeable for patients. The MayoClinic.com stated that as a patient’s metabolism slows further due to the hormone deficiency, she will develop more noticeable symptoms.
Left untreated, the symptoms become more severe over time. In addition to the fatigue and sluggishness, patients may have constipation, muscle weakness and an unexplained weight gain.
Women who have an underactive thyroid may have menstrual periods that are heavier than normal. Patients’ hair and fingernails may become thin and brittle.
Some patients with hypothyroidism may become depressed. Other symptoms of hypothyroidism include having an increased sensitivity to cold, muscle aches and stiffness, muscle weakness, an elevated blood cholesterol level, pale and dry skin, and joint and muscle pain.
As hypothyroidism continues without treatment, patients may develop other symptoms. For example, MedlinePlus noted that patients may develop puffiness in their feet, hands and face.
Patients’ skin may become thicker and their eyebrows may become thinner. Certain senses may become affected.
Late symptoms of hypothyroidism include a decreased sense of smell and taste. Other symptoms include hoarseness and slow speech.
The symptoms of an underactive thyroid can differ in younger patients. For example, in an infant with hypothyroidism, she may have frequent choking and jaundice, which is the yellowing of the whites of the eyes and the skin.
An infant with hypothyroidism may also have a puffy face and a large tongue that protrudes. The MayoClinic.com noted that when hypothyroidism progresses in an infant, it can affect her feeding and developmen.
Untreated cases may result in severe delays in physical and mental capabilities.