McCune-Albright syndrome associated with now-autoimmune type of hyperthyroidism with development of thyrotoxic crisis

We report on a patient having McCune-Albright syndrome (MAS) associated wit h non-autoimmune hyperthyroidism associated with thyrotoxic crisis. Polyost otic fibrous dysplasia developed at age 8, and cafe-au-lait pigmentation wa s noted on the skin. At age 18, he developed hyperthyroidism with multiple adenomatous changes. The hyperthyroidism had been controlled with an antith yroid drug, but the antithyroid medication was discontinued by the patient at age 23. One year later, thyrotoxic crisis developed with fever, convulsi ons and loss of consciousness. Thyroid function tests showed serum concentr ations of free T-4 Of 5.1 ng/dl, and serum TSH of <0.1 <mu>U/ml. Serum thyr oglobulin concentrations were markedly increased (1,280 ng/ml). Three major thyroid-related autoantibodies (TSH receptor antibody, antithyroglobulin, and antimicrosomal antibodies) were not detected in serum. Serum GH concent rations were increased, and not suppressed by the glucose tolerance test, b ut increased paradoxically by TRH. The thyrotoxic crisis was ameliorated by treatment with a beta -adrenergic receptor-blocking agent, glucocoroticoid , iodine, antithyroid drug, and antibiotics. The cause of thyroidal defect in our patient is not considered to be autoimmune hyperthyroidism, but hype rthyroidism due to constitutive activation of G(s)alpha by inhibition of it s GTPase. This paper describes, as far as we know, the first case of MAS as sociated with thyrotoxic crisis. Because hyperthyroidism in this patient re curred quickly after discontinuation of the antithyroid drug, the mode of t reatment for MAS-associated hyperthyroidism appears to be total surgical ab lation or repetitive radioiodine therapy. Copyright (C) 2000 S. Karger AG,B asel.