Familial dysalbuminemic hyperthyroxinemia

Editor-In-Chief: Prab R Tumpati, MD
Obesity, Sleep & Internal medicine
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Familial dysalbuminemic hyperthyroxinemia
Synonyms	FDH
Pronounce	N/A
Specialty	N/A
Symptoms	Elevated thyroxine (T4) levels, normal thyroid-stimulating hormone (TSH) levels
Complications	Misdiagnosis of hyperthyroidism
Onset	Congenital
Duration	Lifelong
Types	N/A
Causes	Genetic mutation in the albumin gene
Risks	Family history of FDH
Diagnosis	Blood tests showing elevated T4, normal TSH, and genetic testing
Differential diagnosis	Hyperthyroidism, euthyroid sick syndrome
Prevention	N/A
Treatment	None required, as it is a benign condition
Medication	N/A
Prognosis	N/A
Frequency	Rare
Deaths	N/A

Familial dysalbuminemic hyperthyroxinemia (FDH) is a rare genetic disorder characterized by elevated levels of total thyroxine (T4) in the blood due to an abnormal binding of thyroxine to serum albumin. This condition is often misdiagnosed as hyperthyroidism, but patients with FDH are typically euthyroid, meaning they have normal thyroid function.

Pathophysiology

FDH is caused by a mutation in the albumin gene, which leads to an altered albumin protein with increased affinity for thyroxine. This results in higher levels of total T4 in the bloodstream, while free T4 levels remain normal. The mutation is inherited in an autosomal dominant pattern, meaning only one copy of the mutated gene is sufficient to cause the disorder.

Diagnosis

Diagnosis of FDH involves blood tests that show elevated total T4 levels with normal free T4 and thyroid-stimulating hormone (TSH) levels. Genetic testing can confirm the presence of the albumin mutation. It is important to differentiate FDH from other causes of hyperthyroxinemia to avoid unnecessary treatment for hyperthyroidism.

Clinical Significance

FDH is clinically significant because it can lead to misdiagnosis and inappropriate treatment. Patients with FDH do not require treatment for hyperthyroidism, as their thyroid function is normal. Awareness of this condition is important for healthcare providers to prevent unnecessary interventions.

Management

No specific treatment is required for FDH, as it does not cause symptoms or complications. Management involves reassurance and education of the patient and their family about the benign nature of the condition.

Also see

• Thyroxine
• Hyperthyroidism
• Thyroid function tests
• Serum albumin