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INTRODUCTION

KEY POINTS

  • Dermatologists may be the first to see patients with thyroid-related conditions and should therefore be familiar with the cutaneous manifestations of thyroid dysfunction.

  • The early recognition of hypo- and hyperthyroidism often lies with the dermatologist as both disorders can have a pronounced impact on the skin.

  • The triggering factors of thyroid disease include iodine deficiency and autoimmune diseases such as diabetes, vitiligo, and alopecia.

  • The incidence of thyroid disease is higher in Caucasian populations than in those with darker skin of color. Skin and hair manifestations of thyroid conditions will still present in patients with skin of color; however, they may appear in a more subtle form than in those with fairer skin.

  • Graves disease is the most common hypothyroid disease associated with cutaneous manifestations. Patients with Graves disease may show clinical signs of acropachy or myxedema.

  • The thyroid cancer syndromes include Sipple syndrome, Cowden syndrome, LAMB (lentigines, atrial myxomas, mucocutaneous myxomas, and blue nevi) syndrome, and NAME (nevi, atrial myxomas, myxoid neurofibromas, and ephelides) syndrome. Papillary carcinoma is the most common form of thyroid cancer in North America.

Dermatologists may be among the first medical professionals to be consulted by individuals with hypo- and hyperthyroid disease. This is because the common dermatoses related to thyroid hormone dysfunction and/or thyroid-specific lesions (eg, cysts or malignancies) are often the first symptoms that patients become aware of. Therefore, dermatologists should be familiar with the broad and varied cutaneous manifestations of an underlying systemic thyroid disease in order to make the correct diagnosis.

EPIDEMIOLOGY

Worldwide, the most common cause of primary thyroid disease is a dietary iodine deficiency; however, this is rarely seen in the Western world.1 Several studies have found that, when compared with other patient groups, African Americans have a lower prevalence of thyroid disease.2,3 Autoimmume thyroid disease is associated with other autoimmune diseases, including vitiligo, alopecia, and diabetes mellitus.4,5,6 Hyperthyroidism tends to affect women more than men (at a ratio of 5:1) and has an overall prevalence of 1%.7 Some studies suggest that there may be a lower incidence of hyperthyroidism in African American patients.1 However, research on indigenous Africans in South Africa suggested that these patients presented more frequently with a complicated form of the disease, including cardiac failure, overt myopathy, and infiltrative ophthalmopathy.8 The presentation is often late and severe, and this may reflect potential educational, socioeconomic, and cultural differences between the African and Caucasian populations in Africa, as well as delays in diagnoses.

A recent study demonstrated that the prevalence of subclinical hypothyroidism among pregnant women was fairly high among Indian patients.9 They also had high rates of thyroid peroxidase (TPO) antibody positivity.9 Therefore, screening for hypothyroidism is often included as a routine test to improve maternal and fetal outcomes.

Among Americans, there is a lower rate ...

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