Expert Reviewed By: Dr. Brandon Colby MD
Dysalbuminemic hyperthyroxinemia (FDH) is a rare genetic disorder that affects the thyroid hormone levels in the body. It is characterized by abnormally high levels of free thyroxine (T4) in the blood, which can lead to misdiagnosis and unnecessary treatment. Understanding the underlying causes, diagnostic methods, and the role of genetic testing in FDH can help healthcare professionals and patients make informed decisions about their health.
Understanding Dysalbuminemic Hyperthyroxinemia
FDH is caused by mutations in the albumin gene (ALB), which encodes the primary protein in blood plasma. These mutations alter the structure of albumin, increasing its affinity for thyroid hormones. As a result, the levels of free T4 in the blood appear to be higher than they actually are, leading to a false impression of hyperthyroidism. However, patients with FDH typically do not exhibit any symptoms of thyroid dysfunction, as the levels of bioactive thyroid hormones remain normal.
Several studies have identified different ALB gene mutations responsible for FDH, such as the R222I mutation and the R218S and R218H mutations found in Chinese patients. Understanding the genetic basis of FDH is crucial for accurate diagnosis and appropriate management of the condition.
Diagnosing Dysalbuminemic Hyperthyroxinemia
FDH can be challenging to diagnose, as the elevated free T4 levels may be mistaken for hyperthyroidism. However, the presence of normal thyroid-stimulating hormone (TSH) levels and the absence of hyperthyroid symptoms can provide clues to the true nature of the condition. A case report of a patient with FDH combined with Graves' disease highlights the importance of considering FDH in the differential diagnosis of inappropriate secretion of TSH.
Various immunoassay methods can be used to measure free T4 levels, but their accuracy in the presence of FDH-causing mutations may vary. A study comparing three immunoassay methods in Chinese patients with FDH found significant differences in the measured free T4 levels, underscoring the importance of selecting the appropriate diagnostic method.
Genetic Testing for Dysalbuminemic Hyperthyroxinemia
Confirming the Diagnosis
Genetic testing can play a pivotal role in the diagnosis of FDH. By analyzing the ALB gene for mutations, healthcare professionals can confirm the presence of FDH and differentiate it from other thyroid disorders. This can prevent unnecessary treatments and ensure that patients receive appropriate care for their condition.
Identifying At-Risk Family Members
FDH is an inherited disorder, and genetic testing can help identify family members who may be at risk for the condition. Early detection of FDH in at-risk individuals can facilitate appropriate monitoring and management of thyroid hormone levels, preventing potential complications and improving overall health outcomes.
Understanding the Protein Structure and Function
Genetic testing can also provide valuable insights into the protein structural aspects of FDH. By identifying the specific ALB gene mutations and their effects on albumin structure, researchers can better understand the molecular basis of the disorder and develop targeted therapies to address the underlying cause of the condition.
Informing Drug Interactions
FDH-causing mutations can also impact the binding of albumin to certain drugs, potentially affecting their efficacy and safety. Genetic testing can help healthcare professionals make informed decisions about drug selection and dosage adjustments for patients with FDH, ensuring optimal treatment outcomes.
Conclusion
Dysalbuminemic hyperthyroxinemia is a rare genetic disorder that can be challenging to diagnose and manage. A comprehensive understanding of the condition, including its genetic basis, diagnostic methods, and the role of genetic testing, is essential for accurate diagnosis and appropriate care. By leveraging the power of genetic testing, healthcare professionals can improve the lives of patients with FDH and their families.
About The Expert Reviewer
Dr. Brandon Colby MD is a US physician specializing in the personalized prevention of disease through the use of genomic technologies. He’s an expert in genetic testing, genetic analysis, and precision medicine. Dr. Colby is also the Founder of and the author of Outsmart Your Genes.
Dr. Colby holds an MD from the Mount Sinai School of Medicine, an MBA from Stanford University’s Graduate School of Business, and a degree in Genetics with Honors from the University of Michigan. He is an Affiliate Specialist of the American College of Medical Genetics and Genomics (ACMG), an Associate of the American College of Preventive Medicine (ACPM), and a member of the National Society of Genetic Counselors (NSGC)