Hyperthyroidism

Hyperthyroidism is a common endocrine disorder. We retrospectively evaluated our 25-year database of 374 patients with hyperthyroidism, reviewing underlying etiologies, treatment strategies and success or failure of various treatments. We also evaluated the role of antibody titers in Graves' disease in predicting ultimate hypothyroidism. Graves' disease was diagnosed in 82% of patients and the remainder had a multinodular toxic goiter or toxic adenoma. 84% of patients were female with a female to male ratio of 5:1. The average age of onset of disease was 48 years (range 11 to 88 years). More than half the patients presented between 30 and 60 years of age (55%). 19% were 30 years of age or younger and 22% were between 60 and 79 years of age. 25% of patients had a clearly defined precipitating stress-event and 38% of patients had a positive family history of thyroid disease. 65% of patients had symptoms for several months to a year. 83% percent of patients had a goiter with an estimated gland weight of 30 to 100 grams. 28% of patients had clinical ophthalmopathy and 11 patients (

More than half of patients had positive anti-microsomal antibody titers. Of the 35 patients with recently measured TSI titers, 25 (71%) had positive titers, and all had Graves' disease. All patients exhibited TSH suppression. Approximately 90% had increased serum T4 levels. 3% (11 patients) had increased T3, and normal T4, consistent with T3 toxicosis. 3% (12 patients) had normal T3 and T4. 78% of patients had homogenous uptake on thyroid scan and the remainder had inhomogenous uptake, or uptake consistent with a toxic adenoma. Mean I^sup 123^ uptake was 47% at 6 hours and 57% at 24 hours. 116 patients received PTU or tapazole for 1 year or longer of whom only 16 patients have had a sustained remission. 20 patients were treated surgically and 8 of these patients were subsequently treated with I^sup 131^. Of those with antibody positivity, 29% became ultimately hypothyroid compared with 14% who had antibody negativity. 304 patients received I^sup 131^ of whom 251 received one therapeutic dose, 47 received 2 doses and 6 received 3 doses. Of those receiving one dose of I^sup 131^, 28% ultimately became hypothyroid and of these 58% were antimicrosomal antibody positive. Of those treated twice, 26% became hypothyroid (66% were antibody positive) and of those treated 3 times, 2 of 6 (33%) became hypothyroid. 73 patients with positive antibody titers developed hypothyroidism after I^sup 131^ while only 33 patients with negative antibody titers developed hypothyroidism.

Our findings support the general experience that Graves' disease is the most common cause of hyperthyroidism, with a female predominance, presenting most often between 30 and 60 years of age. Finally, more than half of the patients had positive antibody titers consistent with a concomitant underlying Hashimotos thyroiditis, in keeping with the general impression of a frequent association between Hashimotos thyroiditis and Graves' disease. The data suggest a greater incidence of I^sup 131^ induced hypothyroidism in patients with positive antibody titers.

MAEVE C. DURKAN, MD, JASMINE JOHN, MD, JOSEPH TUCCI, MD

ROGER WILLIAMS MEDICAL CENTER, BOSTON UNIVERSITY SCHOOL OF MEDICINE, BROWN UNIVERSITY SCHOOL OF MEDICINE

Copyright Rhode Island Medical Society Dec 2004
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