Abstract
Chronic diphenylhydantoin therapy has long been known to be associated with gum hypertrophy; there are scattered descriptions of more generalized tissue proliferation. The present observations were made on a 17 year old boy, one of fraternal twins, who has been on various combinations of diphenylhydantoin, mephobarbital and primidone for the last 5 years because of a seizure disorder. His facies were coarse and acromegaloid, with the suggestion of edema. Hands and feet were normal in size. Height was 68 in. with a linear growth curve since infancy identical with that of his normal twin. Bone age was normal. Serum growth hormone assays done during a glucose tolerance test revealed no abnormal increase of growth hormone. Serum values both of thyroxine by competitive protein binding and of free thyroxine were low (T4CPB = 2.7 μg.% as iodine; FT4 = 0.7 μg.% as iodine). It is tempting to hypothesize that the anticonvulsants have produced an iatrogenic metabolic error of thyroxine metabolism in which the “myxedema” effect predominates. Obviously there has been no hypothyroidism-like effect on linear growth or osseous maturation. It is known that diphenylhydantoin is bound to TBG and may block thyroxine. In addition diphenylhydantoin and certain barbitals may cause adaptation of hydrolase enzymes so as to increase degradation of thyroxine and precursors.
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Gardner, L., Wallach, L. & Gregory, T. COARSE FACIES, ACROMEGALOID FEATURES AND LOW SERUM THYROXINE IN A BOY ON LONG-TERM ANTICONVULSANT THERAPY. Pediatr Res 8, 363 (1974). https://doi.org/10.1203/00006450-197404000-00137
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DOI: https://doi.org/10.1203/00006450-197404000-00137