A T3 immunoassay test helps to determine whether the thyroid is functioning properly. It is primarily done to diagnose hyperthyroidism. T3 is also done to monitor the progress of a patient with a known thyroid disorder. T3 test is also sometimes conducted along with thyroid antibodies test to diagnose diseases such as Graves' disease, which is an autoimmune disorder that is the most common cause of hypothyroidism. Most of the T3 in the blood is attached to the thyroxine binding globulin. Only less than 1% of the T3 remains unattached. A T3 blood test is used to measure both the bound and the free Triiodothyronine. Increased or decreased T3 test result indicates that there is an imbalance between the body's requirement and supply of the hormone. If a patient is being treated with anti-thyroid medication for hyperthyroidism and the T3 is normal, then it is likely that the medication is controlling the condition. If the T3 is elevated, then the medication is not sufficient and the patient may be experiencing symptoms associated with hyperthyroidism. The normal test value for T3 is 100 to 200 ng/dL (nanograms per deciliter).
The T4 immunoassay test helps measure the amount of Thyroxine or T4 in the blood. A T4 immunoassay test is primarily done in response to an abnormal TSH result. Sometimes T4 is done along with TSH blood test. Thyroid hormone screening is commonly performed in newborns in the US as part of newborn screening programs for congenital hypothyroidism which may cause mental retardation if left untreated. False positive results can occur when testing a newborn for congenital hypothyroidism. Therefore normally the test is repeated a few days after initial testing. If the results continue to be abnormal, then additional testing is done. The normal range of a T4 test for an adult is 5 - 11 ug/dL (nanograms per deciliter).
There are other thyroid tests that indicate a malfunction. One such test is the 'Thyroid antibodies' test. This test is used to measure the presence of antibodies against thyroid tissue. Antibodies mean that the person has autoimmune disease such as Hashimoto's Thyroiditis or Graves' disease ( a condition characterized by an enlarged thyroid gland, weight loss without loss of appetite, sweating, heart palpitations, nervousness and inability to tolerate heat).
Thyroxine-binding globulin (TBG) is another thyroid test which detects the TBG which is an important protein in the blood that carries the thyroid hormones T3 and T4. This is a rare test and not done very commonly. Other diagnostic tests that are used to investigate problems with thyroid gland are the thyroid scan, thyroid ultrasound and thyroid biopsy.
Lack of thyroid hormones causes hypothyroidism. Prolonged hypothyroidism can lead to Myxoedema. Myxoedema is a disorder of the skin and tissue owing to long term hypothyroidism. Hypothyroidism occurs due to surgical removal of thyroid glands, atrophic diseases, etc. Partial myxoedema / myxedema, can affect the lower legs of the person, this condition is referred to as pretibial Myxoedema. Rarely Grave's disease can also lead to pretibial Myxoedema. This condition is very common in women, in particular middle aged women. Myxoedema is also known as Gull's disease. If this condition is left untreated, it can cause Myxoedema coma. Myxoedema can be classified into Myxoedema and operative Myxoedema.
Myxoedema is accompanied by the following symptoms - coarse skin, thickening nose, thickening of the skin, puffiness of the eyes, swollen lips, mental disturbances, muscle pain and lethargy. In advanced cases the thyroid gland shrinks and becomes a fibrous mass. Persons suffering from Myxoedema might also suffer brittle hair, weight gain and constipation.
Blood tests are done to check for T3, T4, and TSH levels in the blood. Thyroid profile result helps in diagnosing the condition. In few cases nuclear imaging of the gland is done to study the gland. Thyroid biopsy is not required to diagnose this condition. Treating hypothyroidism is the treatment for Myxoedema. Hypothyroidism is treated through thyroid hormone replacement therapy. In advanced cases of Myxoedema, treatment gets difficult.
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Collection of Pages - Last revised Date: April 8, 2020