Low T3 levels indicate a health problem related to the well functioning of the thyroid. There are several specific laboratory tests which can reveal the existence of a hormonal disorder in the body. T3 is the most important hormone produced by the thyroid, which affects almost every tissue in the body. Thus, any abnormality in its levels has an important impact on one’s health. The other hormone produced by the thyroid is called T4 and through denodidation processes in the follicular cells of the thyroid, T3 is synthesized from T4. Even though T3 has much more effects on the human’s body, it is produced in smaller quantities comparing to T4.
In order to get a conclusive diagnosis when suspecting a thyroidal condition, the doctor will recommend a T3 test after the TSH and/or the T4 test revealed abnormalities. Comparing the results of all these hormonal tests, the doctor may certainly establish a diagnosis. The TSH hormone is also called the thyroid stimulating hormone which takes part in the process of T3 production. The normal level of TSH is situated somewhere between 0.3 and 3.0, of the free T3 test somewhere between 100 to 200 ng/dL and the normal range for the free T4 tests runs to 0.7 to 0.2. The normal levels of a total T3 test are 80 to 220 and of a total T4 tests, 4.5-12.5. Usually when the value is more elevated than the upper limit the patient is suspected of hyperthyroidism which means that his thyroid is overactive. However, the diagnosis is established after a comparison on all the results. A low T3 normal T4 level indicates that the patient is not suffering from a condition related to the thyroid. On the other hand, if both T3 and T4 are in a normal range but TSH is higher than the normal limit, the patient is suspected of mild hypothyroidism but if both T3 and T4 are normal and TSH is lower that the limit the suspected condition is hyperthyroidism. On the other hand, a high TSH, low T4 and low or normal T3 are signs of hypothyroidism. Generally a low free T3 is associated with hypothyroidism. In most of the cases the very first sign of a disease related to the thyroid is indicated by the TSH abnormal levels. However, many of the patients experience the symptoms of this type of disease even if the test results come with a normal TSH. Hypothyroidism is taken into consideration even if TSH levels are normal but T3 is lower. Thus, normal TSH low T3 can still indicated a thyroid related problem. Low TSH and high T4 and T3 suggest hyperthyroidism. Also, low levels of TSH, low or normal T4 and low or normal T3 do not indicate a thyroid related problems but in some cases it can mean a rare pituitary condition or hypothyroidism. Anyhow, the tests results may be influenced by certain medication.
Low T3 levels are almost always linked to thyroid related illnesses, mostly hypothyroidism, conditions that are manageable and treatable with specific medication, under the endocrinologists’ observation.