Thyrotoxic periodic paralysis in Mexican mestizo patients: A clinical, biochemical and HLA-serological study

Background: Thyrotoxic periodic paralysis (TPP) is characterized by episode s of neuromuscular weakness occurring in the context of hypokalemia and hyp erthyroidism and has been predominantly described in Oriental populations. Whereas it is uncommon in Caucasians and Blacks, TPP does occur in individu als of Native American descent. The objective was to analyze the clinical, biochemical, and HLA characteristics of a group of Mexican mestizo patients with TPP, Methods. The sample was comprised of 14 men with TPP diagnosed since Januar y 1990, based on one or more episodes of flaccid paralysis, accompanied by hypokalemia and occurring in the context of clinical and biochemical hypert hyroidism, Eight were available for HLA testing. Results. Hyperthyroidism was diagnosed before the development of periodic p aralysis in five of the patients, whereas in six it occurred afterward. The severity of paralysis did not correlate with the degree of either hypokale mia or hyperthyroidism. An increased frequency of HLA-DR3 was found in Grav es' patients without paralysis but not in those with paralysis, as compared to the general population. Conclusions. TPP is more common than previously thought in Mexicans, in who m it behaves as in other Native American groups. The lack of HLA-DR3 associ ation in Graves' patients with TPP is interesting, but at the moment has no pathophysiological implications. (C) 1999 IMSS, Published by Elsevier Scie nce Inc.