Physico-chemical studies on the thyroid stimulating hormone immunoradiometric assay

Thyroid stimulating hormone (TSH), which is known as thyrotropin, is an anterior pituitary hormone and a glycoprotein with a molecular weight of about 28,000 Daltons. This hormone increases the secretion of thyroxine and triiodothyronine from the thyroid gland. In the present study, the immunoradiometric (IRMA) technique was used for the estimation of TSH, and also the various thermo-kinetic parameters of the assay were determined including temperature, antibody volume, tracer volume, and incubation time. Many thermo-kinetic parameters were calculated, such as the free energy change of (DeltaG degrees ), the enthalpy change (DeltaH degrees ), and the entropy change (DeltaS degrees ) of the reaction. The results obtained were used to determine the order of the reaction and the optimum conditions to perform the assay. The optimum conditions that were obtained from the present studies were used to perform the assay for patient's samples and the results obtained were compared with that of a commercially used kit; the results indicated the high correlation between the traditional (commercial) method and the studied one.