Major method-specific differences in the measurement of intact parathyroid hormone: studies in patients with and without chronic renal failure

Abstract

The instability of synthetic hPTH over extended storage periods may affect primary standard material. The consistent inter-assay differences and the over-recovery observed in external quality assessment programmes for the Immulite assay may have best been explained by differences in calibration and the relative cross-reactivities and/or kinetics of the two assay systems for specific parathyroid fragments.