Hypothyroidism is a syndrome that is caused by an insufficient production of thyroid hormones. Thyroid stimulating hormone (TSH) is increased with primary hypothyroidism, and the main cause is usually Hashimoto's disease. Secondary hypothyroidism is caused by the insufficiency of another gland called the hypothalamus. It occurs because this gland cannot produce thyrotrophic-releasing hormone (TRH). In other cases, the pituitary gland, which produces thyroid releasing hormone (TSH), does not work efficiently. There are many signs and symptoms associated with hypothyroidism.
Hormone Levels
In hypothyroidism, a blood test will reveal that that the serum concentration of TSH is above normal. The serum levels of T3 and T4, which are hormones secreted by the thyroid gland, are below normal.
Slow Metabolism
The thyroid gland controls metabolism, but because it is not working efficiently, the metabolism will slow down. This will lead to a decrease in the heart rate, called bradycardia. Because the arteries of the heart will dilate more, an enlarged heart may be seen in individuals with hypothyroidism. If left untreated, this can lead to heart failure.
Changes of Appearance
Many facial changes may be present in people with hypothyroidism. The facial expression may be dull; the face may become puffy or swell and the eyelids may droop. Swelling may also be seen in the legs. The skin may become dry and coarse and the voice may become hoarse. The hair may also become thick, dry and coarse, and there may be some hair loss. The nails become brittle and break easily. Unexplained weight gain or difficulty in losing weight may also occur due to a decrease in metabolism.
Changes in the Body
Signs of hypothyroidism can be evident in the changes that occur within the body. Weakness in muscles, fatigue and depression are common; muscle cramps and stiffness may also be present. Cold intolerance can also occur in many individuals. Memory loss, difficulty concentrating and confusion may be seen; these may be confused with signs of aging in the elderly. The body may also lose its sensitivity to insulin, which can cause a rise in blood sugar (hyperglycemia). This puts people at risk for the development of diabetes. Because of decreased metabolism, constipation is typical among people with hypothyroidism. Women may experience heavier than normal periods, which can cause iron deficiency.
High Cholesterol
Hypothyroidism can cause blood cholesterol to increase due to the slowing down of the metabolism. This can cause the cholesterol to reach dangerous levels and can lead to heart disease. By controlling hypothyroidism with the proper medication, cholesterol levels may normalize.
Coma
If hypothyroidism is left untreated, signs such as weakness, cold intolerance or hypothermia, and hypoventilation will progress. This can lead to shock and death, and it requires immediate medical help.
References
- "Drug Information Handbook 15th Edition"; Charles F. Lacy, RPh, PharmD, FCSHP, Lora L. Armstrong, RPh, PharmD, BCPS. et al; 2007
- "Basic and Clinical Pharmacology"; Bertram G. Katzung; 2008
- Merck: Hypothyroidism
