Coagulation disorder due to apparent inadvertent heparin administration

A new competitive binding assay, which measures the concentration of heparin rather than its activity, was used to confirm the presence of a high concentration of heparin in blood samples from a patient which showed unexpected gross prolongation of thrombin time (TT) and activated partial thromboplastin time (APTT). Extrapolation of the heparin concentration enabled estimation of the likely time of administration and the probable dose given. It is possible that an error in dosage may have arisen due to the striking resemblance of vials containing different amounts of heparin marketed by different manufacturers. There is a need for the adoption by manufacturers of a standard coding scheme for vials containing different amounts of heparin (as is adhered to in the case of some drugs, e.g. warfarin), in order to pre-empt this possible source of error.