Familial Dysalbuminemic Hyperthyroxinemia by Albumin Gene Variant (R242H) in a 19-Year-Old Male: A Case Report

Familial dysalbuminemic hyperthyroxinemia (FDH) is the most common inherited cause of high serum total thyroxine (T4) levels in clinically euthyroid individuals. Mutant albumin coding gene (ALB) interferes free T4 assays and leads to discordant thyroid function tests. We describe a 19-year-old male harboring a heterozygous c.725G > A (p.Arg242His) variant using Sanger sequencing for his ALB, which is the second FDH case reported in South Korea. Appropriate genetic testing for subjects suspicious of FDH would prevent unnecessary repeat tests, although the prevalence of FDH is very low in the Asian population.