A condition of the thyroid (a small butterfly-shaped gland at the front of the neck), hyperthyroidism occurs when the thyroid produces excessive thyroid hormones, namely T4 and T3. High amounts of these hormones speed up the metabolic rate, causing what is called a “hypermetabolic state.” When the body is in the hypermetabolic state, the heart may present with an abnormally elevated rate, which may be accompanied by elevated blood pressure.
John Macoviak MD MBA , in a clinical study with other researchers using sheep as a model, took measurements of a hormone called serum thyrotropin TSH in 21 coronary artery bypass surgery patients with no thyroid disease diagnosis (group 1), 14 heart transplant recipients with no thyroid disease diagnosis (group 2), as well as 158 random patients hospitalized for nonthyroidal illnesses. Evaluation of the results from the first two groups showed a direct relationship between TSH and free T4 FT4, and patients with prolonged subnormal TSH level (greater than one week) also had subnormal FT4. This strongly suggests the same results in severely ill non-thyroid-condition patients. Subsets of other groups, on the other hand, showed an inverse relationship between TSH and FT3 or FT4. In addition, hyperthyroidism was confirmed in 5 of 6 patients with suppressed TSH. In conclusion, TSH measurement was suggested as a useful tool in confirming mild hyperthyroidism as an addition to other tests.
