Artifactually Elevated Serum-Free Thyroxine Levels Measured by Equilibrium Dialysis in a Pregnant Woman with Familial Dysalbuminemic Hyperthyroxinemia
| Autor: | Katsumi Yoshida, Saeko Hoshikawa, Kouki Mori, Sadayoshi Ito, Nobuko Kaise, Yoshinori Nakagawa |
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| Rok vydání: | 2004 |
| Předmět: |
Adult
Proband medicine.medical_specialty Guanine Proline Arginine Globulin Endocrinology Diabetes and Metabolism Radioimmunoassay Cytosine Thyroxine-Binding Proteins chemistry.chemical_compound Endocrinology Pregnancy Internal medicine medicine Humans Equilibrium dialysis Serum Albumin Genes Dominant biology Albumin medicine.disease Pregnancy Complications Hyperthyroxinemia Thyroxine Amino Acid Substitution chemistry Familial dysalbuminemic hyperthyroxinemia Mutation biology.protein Female Hemofiltration Artifacts Dialysis Metabolism Inborn Errors hormones hormone substitutes and hormone antagonists |
| Zdroj: | Thyroid. 14:155-160 |
| ISSN: | 1557-9077 1050-7256 |
| Popis: | Familial dysalbuminemic hyperthyroxinemia (FDH) is a familial autosomal dominant syndrome caused by abnormal albumin with an increased affinity for thyroxine (T4). Two types of mutations in the albumin gene, replacing the normal arginine 218 with a histidine (R218H) or a proline (R218P), have been reported to cause FDH. Here, we report a pregnant Japanese woman with FDH caused by the mutant albumin R218P. She had extremely elevated total T4 levels but normal TSH. While the majority of T4was bound to albumin, T4 binding to thyroxine-binding globulin (TBG) was progressively increased throughout pregnancy. Her infant also had elevated serum T4 but normal thyrotropin (TSH). The presence of a guanine to cytosine transition in the second nucleotide of codon 218 of the albumin gene, resulting in a substitution of proline for the normal arginine (R218P), was revealed in the proband. Serum free thyroxine (FT4) levels were increased when measured with some commercial kits including equilibrium dialysis followed by radioimmunoassay (RIA) but not when determined by RIA after ultrafiltration of sera. These results indicate an increased T4 binding to TBG during pregnancy in the patients with FDH. Furthermore, our results suggest that normal serum FT4 determined by equilibrium dialysis is not an ultimate standard for the diagnosis of FDH in the patients with the mutant albumin R218P. |
| Databáze: | OpenAIRE |
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