Do thyroid disorders cause hair loss?
Yes! Thyroid malfunction is one of the causes for hair loss.Thyroxine (T4) is the main hormone produced by the thyroid gland; but it is less potent than T3. The thyronines act on nearly every cell in the body, including the hair follicles (HFs). Within the cells, much of T4 is converted into T3 by deiodinase (iodide peroxidase) enzyme, which is also involved in the activation or deactivation of thyroid hormones. Deiodinase and its isoforms are selenium-containing enzymes and selenium deficiency can impact T3 production.
Hypothalamus ›› thyrotropin-releasing hormone ›› pituitary gland ›› thyroid stimulating hormone ›› thyroid gland ›› thyroxine and triiodothyronine.
Hypothyroidism hair loss
Hypothyroidism is a common endocrine disorder in which sufficient thyroxine hormones are not produced. The common symptoms include, slow pulse rate, dry skin, hair loss, cool extremities, weight gain with poor appetite, abnormal sensation, irregular menstrual cycles, delayed puberty and poor hearing. Iodine deficiency is the most common cause of low thyroxine hormones.Another common cause is Hashimoto's thyroiditis or chronic lymphocytic thyroiditis. It is an autoimmune disease in which the endocrine cells are attacked by the patient's immune bodies. The treatment is by hormonal replacement with agents such as levothyroxine or triiodothyronine. In some cases, women, post pregnancy get affected by postpartum thyroiditis causing low thyroid hormone levels.
Hyperthyroidism hair loss
An excess of circulating free thyroxine can cause a number of disorders. The pace of all the cellular processes in the body is speeded up. Some of the symptoms are nervousness, irritability, sweating, palpitation, hand tremors, anxiety, loss of sleep, thinning of the skin, fine brittle hair, loss of the outer third of the eyebrows, scalp hair breakage and loss, increased appetite, weight loss, digestive system hypermotility and muscular weakness.Graves' disease (or Flajani-Basedow-Graves disease) is the major cause of excessive thyroxine production. It is an autoimmune disease affecting the thyroid glands causing their enlargement. Apart from affecting many organs, it causes bone loss by an increased excretion of calcium and phosphorus in the urine and stool. Graves' disease may cause ophthalmopathy with ocular manifestations such as soft tissue inflammation, proptosis and optic nerve compression. The optic nerve involvement may cause loss of vision.
The second most common cause of excess thyroxine production, after Graves' disease, is toxic multinodular goiter. There is excess production of thyroxine hormones from functionally autonomous thyroid nodules which do not require stimulation from TSH. Another cause of excess thyroxine production is toxic thyroid adenoma, a benign tumor of the thyroid gland.
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Reference: 1.Ambooken Betsy, MP Binitha, S Sarita. Zinc Deficiency Associated with Hypothyroidism: An Overlooked Cause of Severe Alopecia. Int J Trichology. 2013 Jan-Mar; 5(1): 40–42. 2.Maya Vincent, Krishnan Yogiraj. A Descriptive Study of Alopecia Patterns and their Relation to Thyroid Dysfunction. Int J Trichology. 2013 Jan-Mar; 5(1): 57–60. 3.Shrivastava SB. Diffuse hair loss in an adult female: approach to diagnosis and management. Indian J Dermatol Venereol Leprol. 2009 Jan-Feb;75(1):20-7; quiz 27-8. 4.van Beek N, Bodó E, Kromminga A, Gáspár E, Meyer K, Zmijewski MA, Slominski A, Wenzel BE, Paus R. Thyroid hormones directly alter human hair follicle functions: anagen prolongation and stimulation of both hair matrix keratinocyte proliferation and hair pigmentation. J Clin Endocrinol Metab. 2008 Nov;93(11):4381-8. |
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