Cutaneous Manifestations of Hyperthyroidism

Abstract

The key to diagnosing hyperthyroidism from a dermatologic perspective is based on having a high index of suspicion that excess thyroid hormone is responsible for the patient's signs and symptoms. As there are no definitive cutaneous manifestations of hyperthyroidism, a careful review of systems may yield important clinical clues to the diagnosis: Is the patient intolerant of heat? Has there been weight loss? Has the patient experienced any palpitations? Have the bowel habits changed? The unique challenge lies in when systemic symptoms are absent or vague, and the skin manifestations are subtle. Should one routinely check a thyroid-stimuating hormone (TSH) level when the only dermatologic finding is onycholysis? Should one obtain a TSH level before administering botulinum toxin for axillary hyperhidrosis with an otherwise unremarkable review of systems? Should you check thyroid function studies for patients presenting with alopecia areata? There are no definitive answers to these questions. Obviously, the yield will be higher in those patients who have several signs and symptoms referable to a hyperthyroid state. It is my opinion that for isolated findings, such as onycholysis or palmoplantar hyperhidrosis, with an unremarkable review of systems, screening for hyperthyroidism is not mandatory. On the other hand, I believe that it is appropriate to check a TSH level in a woman presenting with alopecia, even if there are no associated constitutional symptoms. When patients present with other autoimmune diseases (i.e., chronic idi-opathic urticaria, dermatitis herpetiformis, lichen sclerosus, etc.) in which there is an increased risk for autoimmune thyroid disease, I think it is reasonable to check for thyroid autoantibodies (anti-thryroglobulin, antithyroid peroxidase), especially if there is a positive family history for autoimmune diseases (notably diabetes mellitus or autoimmune thyroid disease). If positive, these patients may be at a greater risk for the development of autoimmune thyroid disease and should be screened periodically (every 3–5 years) with a TSH assay unless clinical circumstances dictate otherwise. In this era of evidence-based medicine, diagnosing hyperthyroidism is still founded on clinical acumen. Fortunately, a clinician's suspicions are easily confirmed or refuted by straightforward laboratory testing. Maintaining an appropriate index of suspicion for hyperthyroidism will allow patients to be diagnosed and treated expediently, thereby greatly increasing their quality of life