A cytochemical section-bioassay for thyrotropin

A cytochemical section-bioassay of thyrotropin has been developed which retains the sensitivity of the earlier segment-assay (10(-4) microunits/ml) and allows a considerable increase in the rate at which these within-animal bioassays can be done. The index of precision (n=23) was 0.11 +/- 0.06; intra-assay variation was 1.3%; inter-assay variation was 10.9 +/- 6%. Fiducial limits (p = 0.95) ranged from 65-150% to 78-127%. The system is also capable of detecting thyroid-stimulating immunoglobulins.