Derm Dx: A 36-year-old woman with dry skin, shin and ankle lesions and onycholysis

Graves disease is an autoimmune thyroid disorder that occurs more often in women than men. About 20% to 30% of patients have a genetic basis for the disease. Researchers have identified several genes associated with the disorder including: CD40, CTLA-4,...

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Graves disease is an autoimmune thyroid disorder that occurs more often in women than men. About 20% to 30% of patients have a genetic basis for the disease.

Researchers have identified several genes associated with the disorder including: CD40, CTLA-4, thyroglobulins, TSH receptor and PTPN22. Infectious pathogens, including Yersinia entercolitica and Borrelis burgdorferi have also been implicated. Interferon beta-1b, interleukin-4 therapy and thyroid trauma are other environmental factors thought to be involved.

Physical findings associated with Graves disease include pretibial myxedema (about 5% to 10% of patients) and ophthalmopathy, including lid retraction, proptosis, impairment of extraocular motion, visual loss in severe optic nerve involvement and periorbital edema. Opthalmopathy is often worse in patients who have dermatologic involvement.

Patients with Graves disease have a diffusely enlarged, smooth thyroid gland, and may experience edema, acropachy and onycholysis in the extremities.

Psychiatric symptoms may be present and include: restlessness, anxiety, irritability, insomnia and depression.

Diagnosis

Clinicians should screen patients suspected of  Graves disease with a third generation thyrotropin assay for the presence of thyrotropin-receptor antibodies.

Other markers of thyroid autoimmunity include thyrotropin receptor blocking antibodies and anti-sodium iodide symporter antibodies.

Increased radioactive idodine uptake diffusely distributed over the entire thyroid gland on imaging studies, also indicates Graves disease.

Ocular proptosis, or abnormal protrusion of they eyeball occurs in 25% to 30% of patients and is considered a hallmark of the disease.

Treatment

Radioactive iodine and antithyroid medications are two treatment options to block the syntheses of thyroid hormones and correct high thyroid hormone levels. The two medications should not be prescribed together as antithyroid drugs can reduce the efficacy of radioactive pharmaceuticals.

Antithyroid drugs should be discontinued two days to two weeks prior to radioactive iodine therapy.

Clinicians should warn patients that relapse occurs in more than 50% of patients who receive antithyroid drugs. Radioiodine dosage ranges from 5 to 15 mCi and depends on estimated patient thyroid weight and radioiodine uptake. Patients who have larger goiters may require higher dosages.

Radioiodine may exacerbate existing opthalmopathy in patients with Graves disease, but should not influence clinicians’ choice of therapy. Patients with severe opthalmopathy should be treated concurrently with glucocorticoids and orbital radiotherapy or decompression.

As many as 64% of patients with Graves opthalmopathy experience spontaneous improvements in eyesight, whereas 10% to 20% progress gradually for years and another 2% to 5% experience worsening visual impairment.

Improvements in thyroid function tests usually occur within two to three months of treatment initiation, but continued patient follow-up and thyroid monitoring are necessary. Those with hypothyroidism may require lifelong thyroid hormone therapy.

Topical steroids and pulse glucocortiodi therapy may be useful in treating pretibial myxedema. Surgical thyroidectomy is reserved for patients with large goiters, compressive symptoms, those who experience treatment failure with other drugs, and pregnant patients.

Graves is generally managed in outpatient settings, and many patients become hypothyroid and require hormone replacement therapy.

References

1.     Sai-Ching JY et al.  Graves disease. Medscape Reference. Acessed online June 10, 2011.

2.     Freedberg IM, Isin AZ, Wolff K, et al. Fitzpatrick’s Dermatology in General Medicine (5^th ed.). 1999. New York: McGraw-Hill.