Summary about Disease
Thyroid hormone resistance (THR) is a rare condition in which the body's tissues do not respond normally to thyroid hormone. Despite normal or elevated levels of thyroid hormone in the blood, individuals with THR may exhibit a variety of symptoms, ranging from hypothyroidism to hyperthyroidism, or may even be asymptomatic. The underlying cause is typically a genetic mutation in the thyroid hormone receptor gene (THRB).
Symptoms
Symptoms vary widely depending on the degree of resistance and the specific tissues affected. Some common symptoms include:
Hypothyroid-like symptoms: Fatigue, weight gain, constipation, cold intolerance, dry skin, slow heart rate, goiter.
Hyperthyroid-like symptoms: Anxiety, rapid heart rate, palpitations, heat intolerance, excessive sweating, tremor.
Other symptoms: Attention deficit hyperactivity disorder (ADHD), learning disabilities, short stature, delayed bone age. Many individuals with THR are asymptomatic.
Causes
The primary cause of thyroid hormone resistance is a genetic mutation in the THRB gene, which encodes the thyroid hormone receptor beta. These mutations impair the ability of the receptor to bind to thyroid hormone and regulate gene expression. In rare cases, resistance can develop without an identifiable mutation.
Medicine Used
Treatment strategies vary depending on the individual's symptoms and hormone levels.
L-thyroxine (T4): Higher-than-normal doses of L-thyroxine may be prescribed to overcome the resistance and achieve a euthyroid state in some tissues.
Triiodothyronine (T3): In some cases, T3 may be used in combination with T4.
Beta-blockers: Beta-blockers may be prescribed to manage hyperthyroid symptoms such as rapid heart rate and anxiety.
Other medications: Other medications may be used to address specific symptoms such as ADHD or constipation.
D-triiodothyronine (D-T3): Is an experimental medicine that might be prescribed.
Is Communicable
No, thyroid hormone resistance is not communicable. It is primarily a genetic condition.
Precautions
Genetic counseling is recommended for individuals with THR who are planning to have children.
Individuals with THR should be monitored regularly by an endocrinologist to adjust treatment as needed.
Inform all healthcare providers about the diagnosis of THR.
How long does an outbreak last?
Thyroid hormone resistance is not an outbreak-related disease. It is a chronic condition present from birth.
How is it diagnosed?
Diagnosis typically involves:
Thyroid function tests: Elevated levels of T3 and T4 with normal or slightly elevated TSH.
Clinical evaluation: Assessment of symptoms and family history.
Genetic testing: Sequencing of the THRB gene to identify mutations.
Exclusion of other conditions: Ruling out other causes of thyroid dysfunction.
Timeline of Symptoms
Symptoms can manifest at any age, from infancy to adulthood. Some individuals may be diagnosed in childhood due to developmental delays or ADHD, while others may be diagnosed later in life due to symptoms such as fatigue or anxiety. Some may never experience any symptoms.
Important Considerations
The severity of THR varies widely.
Treatment should be individualized based on the patient's symptoms and hormone levels.
Long-term monitoring is essential to manage the condition effectively.
Patients should be educated about their condition and actively participate in their care.
Research is ongoing to better understand the pathophysiology and treatment of THR.