An Improved Bio-assay for TSH by Modification of the Method of McKenzie

Abstract

The bio-assay method for thyrotrophin (TSH) described by McKenzie has been modified by the application of a design balanced for residual effects. The modified method has an increased sensitivity (0.006 ImU TSH) compared to the method of McKenzie (0.025 ImU) and an average index of precision ([lambda]) of 0.188. Linearity of the dose-response curve has been demonstrated over the range 0.006 to 0.80 ImU. The sensitivity and precision obtained are greater than previously reported for an in vivo bio-assay method for TSH. The method is best suited for the estimation of small quantities of TSH in a limited number of samples and is capable of detecting changes in circulating TSH in the normal rat.