Viscosity-based detection: addressing HIL interference and sample integrity

Laboratory experts continue to be divided about the effect of haemolysis, icterus and lipaemia (HIL) on sample integrity and therefore the accuracy of patient results. In one study, 5.5% of samples received in the laboratory are rejected due to pre-analytical problems, and, of these, about a fifth are due to HIL.¹ This proportion may sometimes be even higher. When a replacement sample has to be requested, this can risk the patient outcome and possibly delay treatment. Repeat testing also brings an additional care cost, with the patient remaining longer in the hospital or clinic.

            Supported by manufacturer-led initiatives, detecting HIL interference for clinical chemistry assays has become an accepted part of laboratory practice. The controversy has now spread to coagulation, with as many articles stating that samples with HIL interferences do have an impact as those that say it does not for routine parameters.

When assessing the risk of interference for coagulation, a laboratory needs to differentiate between clotting assays and chromogenic and immunoturbidimetric assays, as well as the different detection systems used in coagulation analysers for clotting assays. In addition, the specific challenge of haemolysed samples and assessing the biological impact need to be considered.