Generalized resistance to thyroid hormone
Overview
Thyroid hormone resistance describes a rare syndrome where the thyroid hormone levels are elevated but the thyroid stimulating hormone (TSH) level is not suppressed, or not completely suppressed as would be expected
Symptoms
* Hypothyroidism * Deaf-mutism * Increased thyroid hormone level * Goiter * Tachycardia
Causes
The most common cause of the syndrome are mutations of the β (beta) form of the thyroid hormone receptor, of which over 100 different mutations have been documented. Mutations in MCT8 and SECISBP2 have also been associated with this condition.
Diagnosis
The characteristic blood test results for this disorder can also be found in other disorders (for example TSH-oma (pituitary adenoma), or other pituitary disorders). The diagnosis may involve identifying a mutation of the thyroid receptor, which is present in approximately 85% of cases
Treatment
Treatment varies vastly from person to person but what is common to all are the high doses of thyroid hormone necessary before a patient feels well. First, treatments can be desiccated or synthetic. Then, they can be either T3, T4 or combination T3/T4 drugs. Dr. Lowe has published the most extensive guidelines for properly medicating those with thyroid hormone resistance. Also note, that not all tissues absorb thyroid hormone at the same rate. The heart for example, may absorb at a higher rate than the lungs and muscles. This means, patients may need other drugs to supplement this difference in absorption rate. For many, this includes a beta blocker to reduce stimulation on the heart and allow for a higher hormone dose to better alleviate muscle or lung resistance. It is a balancing act that can only be adjusted by your symptoms and medical tests.