Samuel Refetoff1,2,3, Neal H Scherberg1, Chao Yuan4, William Wu4, Zengru Wu4, Michael J McPhaul4. 1. Department of Medicine, The University of Chicago, Chicago, Illinois. 2. Department of Pediatrics, The University of Chicago, Chicago, Illinois. 3. Department of Committee on Genetics, The University of Chicago, Chicago, Illinois. 4. Endocrine Division, Quest Diagnostics Nichols Institute, San Juan Capistrano, California.
Abstract
Background: Euthyroid individuals with familial dysalbuminemic hyperthyroxinemia (FDH) have often falsely elevated serum free thyroxine (fT4) concentrations determined by different automated immunoassays. Methods: We measured serum fT4 using direct dialysis coupled with tandem mass spectrometry (fT4 DDMS) in individuals with the common albumin gene mutation (ALB R218H) from 14 FDH families and compared them with results obtained by direct immunometric assay (fT4 DIMM) and free thyroxine index (fT4I). Results: While all 14 individuals with FDH had elevated total serum T4, the fT4 measured by DIMM was elevated in 12, by fT4I in 5, and by DDMS in 1. Conclusion: The latter method greatly reduced the discordance of fT4 results relative to thyrotropin in FDH.
Background: Euthyroid individuals with familial dysalbuminemic hyperthyroxinemia (FDH) have often falsely elevated serum free thyroxine (fT4) concentrations determined by different automated immunoassays. Methods: We measured serum fT4 using direct dialysis coupled with tandem mass spectrometry (fT4 DDMS) in individuals with the common albumin gene mutation (ALB R218H) from 14 FDH families and compared them with results obtained by direct immunometric assay (fT4 DIMM) and free thyroxine index (fT4I). Results: While all 14 individuals with FDH had elevated total serum T4, the fT4 measured by DIMM was elevated in 12, by fT4I in 5, and by DDMS in 1. Conclusion: The latter method greatly reduced the discordance of fT4 results relative to thyrotropin in FDH.
Entities:
Keywords:
FDH; albumin; free T4; mass spectrometry; mutation
Authors: Solomon Maximo Greenberg; Alfonso Massimiliano Ferrara; Everton S Nicholas; Alexandra M Dumitrescu; Vivian Cody; Roy E Weiss; Samuel Refetoff Journal: Thyroid Date: 2014-03-21 Impact factor: 6.568
Authors: Theodora Pappa; Alfonso Massimiliano Ferrara; Samuel Refetoff Journal: Best Pract Res Clin Endocrinol Metab Date: 2015-09-30 Impact factor: 4.690