Relationship between serum free thyroid hormone concentrations and target organ responsiveness in thyroid disease...

Relationship between serum free thyroid hormone concentrations and several markers of peripheral tissue response to thyroid status was studied in 24 patients with hyperthyroidism, 17 with euthyroidism with goiter and 10 with primary hypothyroidism before and after the initiation of standard forms of treatment. Before treatment, serum free T4 correlated significantly, either positively or negatively, with the basal metabolic rate (BMR), duration of the achilles tendon reflex (ATR), resting pulse rate (RPR), serum total cholesterol (T-cholesterol), ratio of the pre-ejection period to the left ventricular ejection time (PEP/LVET), serum high density lipoprotein (HDL) and creatine phosphokinase (CPK) in the descending order. Serum free T3 also correlated significantly all the these parameters. After treatment, changes in both serum free T4 and free T3 correlated well with those of the BMR and ATR in the patients with hyperthyroidism, and with those of the ATR, serum CPK and T-cholesterol in the patients with hypothyroidism. These results indicate that these peripheral parameters correlated well with serum free thyroid hormone concentrations in thyroid disease patients. Therefore, these parameters can be used to assess thyroid functions in patients with thyroid hormone resistance.