Hair Foundation
Hair Loss and Hypothyroidism

Lisa Lambert
January 16, 2009

Hypothyroidism is a common condition that affects about 3-5 % of the population and is found more commonly in women than men. It is a condition that develops when the body does not produce enough thyroid hormone or becomes resistant to thyroid hormone. Since thyroid hormone works throughout the body, there are many possible symptoms that can develop in hypothyroidism including tiredness, cold intolerance, weight gain, constipation, depression, skin changes, dry hair and hair loss. The symptoms can develop slowly over the course of years. If not treated, hypothyroidism can progress to more serious symptoms. However, once diagnosed, hypothyroidism is generally a highly treatable condition resulting in eventual resolution of symptoms.


The thyroid gland, located in the lower part of the neck, produces thyroid hormone. Thyroid hormone circulates throughout the body and regulates metabolism, cellular processes, growth and development. The thyroid hormone is critical in cell division at the hair follicle. Cell division at the hair follicle affects initiation and rate of hair growth and hair loss.

The hypothalamus is the part of the brain that produces a hormone known as thyrotropin releasing hormone (TRH). TRH signals the pituitary gland to produce thyroid-stimulating hormone (TSH). TSH then signals the thyroid gland to produce thyroid hormone. Thyroid hormone then travels throughout the body. If there is enough thyroid hormone, then the thyroid hormone tells the pituitary gland to stop producing as much TSH. If there is not enough thyroid hormone, then the thyroid hormone tells the pituitary to produce more TSH to compensate. Thus, high levels of TSH in the blood is a likely indication of low thyroid hormone (or low effect) in the body.


Hypothyroidism occurs when there is not enough thyroid hormone in the body. The symptoms of hypothyroidism can be confused with several different medical conditions and some people have no symptoms early in the disease, which often makes it difficult to diagnose. Diagnosis is made by a simple blood test of TSH and testing of thyroid hormone levels. In general, a high level of TSH, indicates a low level of thyroid hormone or the presence of hypothyroidism. The laboratory findings can get more complicated and sometimes requires the expertise of a hormone expert (endocrinologist).

Effects on Hair

Hypothyroidism causes various changes in hair and hair loss can be common. While hair loss is common for about half of people with hypothyroidism, a larger percent of people with hypothyroidism see changes in texture, dryness and slowed growth. Research has shown that people with hypothyroidism have slower cell division in hair follicles and, thus, slower hair growth. People with hypothyroidism also produce less sebum from the sweat glands in the scalp leading to dry, brittle hair. Less sebum also puts people more at risk of fungal infections of the hair follicles. Hair loss can spread over the scalp and the loss of the outside third of the eyebrows in not uncommon with hypothyroidism.


The best way to prevent hair loss and damage from hypothyroidism is by early diagnosis and treatment of the underlying cause of the condition. Treatment varies depending on the underlying source of the hypothyroidism. The most common treatment is replacing the low thyroid hormone in the body with oral supplements. Once this lack of thyroid hormone is corrected, hair loss should halt and hair growth resume.