Thyroid dysfunction and hair loss
Pro Research Analysisby 
Searched over 200M research papers
Thyroid Dysfunction and Hair Loss: Key Mechanisms and Types of Hair Loss
Thyroid hormones play a crucial role in the growth, development, and maintenance of hair follicles. Both hypothyroidism and hyperthyroidism can lead to hair loss, with the most common types being telogen effluvium, alopecia areata, and androgenetic alopecia. Thyroid dysfunction can disrupt the normal hair growth cycle, leading to increased hair shedding and changes in hair quality and structure 138.
Hypothyroidism, Hyperthyroidism, and Hair Shedding
Both underactive (hypothyroidism) and overactive (hyperthyroidism) thyroid conditions are linked to diffuse hair loss. Hypothyroidism is particularly associated with more severe hair loss compared to hyperthyroidism or normal thyroid function. Patients with hypothyroidism often experience widespread hair shedding, and studies have shown that hair shaft abnormalities, scale changes, and vascular changes are more common in these individuals 149. Hyperthyroidism can also cause hair loss, but the severity is generally less than that seen in hypothyroidism .
Telogen Effluvium and Thyroid Dysfunction
Telogen effluvium (TE) is a common form of hair loss characterized by excessive shedding of resting (telogen) hairs. Thyroid dysfunction, especially hypothyroidism, is a significant cause of TE. Patients with hypothyroidism and TE tend to have more severe hair loss than those with normal thyroid function or hyperthyroidism, highlighting the importance of thyroid testing in patients presenting with TE 19.
Alopecia Areata and Autoimmune Thyroid Disease
Alopecia areata (AA) is an autoimmune condition that causes patchy hair loss. There is a recognized association between AA and autoimmune thyroid diseases, particularly Hashimoto's thyroiditis and hypothyroidism. Some studies suggest that AA may be more severe in patients with thyroid dysfunction or positive thyroid antibodies, although the strength of this association varies and routine thyroid screening in all AA patients remains debated 78. However, not all studies find a significant link between AA and abnormal thyroid function tests .
Diffuse Hair Loss in Women and Thyroid Function
Abnormal thyroid function is found in a significant number of women with diffuse hair loss, especially those with other systemic diseases. Screening for thyroid dysfunction is recommended in adult women presenting with diffuse hair loss, as thyroid abnormalities may be present even in the absence of other symptoms .
Premature Hair Greying and Thyroid Dysfunction
Emerging evidence suggests that thyroid dysfunction may also contribute to premature hair greying (PHG), possibly through mechanisms involving oxidative stress. Higher thyroid-stimulating hormone (TSH) levels have been observed in individuals with PHG compared to healthy controls, indicating a potential link between thyroid status and early loss of hair pigment .
Diagnostic Insights: Dermoscopy and Laboratory Testing
Dermoscopy can reveal specific signs of inflammation and hair shaft abnormalities in hypothyroid patients with hair loss, supporting the role of thyroid dysfunction in hair disorders. Laboratory testing for thyroid function, including TSH, free T4, and thyroid antibodies, is important in the diagnostic workup of patients with unexplained hair loss 249.
Other Contributing Factors
While thyroid dysfunction is a significant cause of hair loss, other factors such as low serum ferritin and vitamin D deficiency can also contribute, especially in women with diffuse hair loss. These should be considered alongside thyroid testing in the evaluation of hair loss .
Conclusion
Thyroid dysfunction, particularly hypothyroidism, is a well-established cause of various types of hair loss, including telogen effluvium and, to a lesser extent, alopecia areata and premature hair greying. Screening for thyroid abnormalities is important in patients with unexplained or severe hair loss, especially in women and those with other autoimmune conditions. However, not all cases of hair loss are linked to thyroid dysfunction, and a comprehensive evaluation including other nutritional and systemic factors is recommended for optimal management 1234+5 MORE.
Sources and full results
Most relevant research papers on this topic