An overview on interference in clinical immunoassays: A cause for concern

Abstract

Immunoassays are rapid, simple, cost-effective, robust and sensitive laboratory techniques that are extensively used in many important areas of clinical medicine such as diagnosis, prevention, treatment and management of diseases. Universally, it is one of the most extensively used in vitro diagnostic testing methods, and its demand has been increasing exponentially over the past four decades. Routinely, these methods can quantify minute amounts of diverse analytes such as hormones, antibodies, proteins and drugs present in highly complex biological fluids, such as serum, urine, sweat, meconium and cerebrospinal fluid. Immunoassays are successful techniques that can detect up to picomolar concentrations using antigen–antibody reactions without the need of prior extraction. Although immunoassays are useful techniques that help physicians to take quick decisions, they too are subjected to interference from both exogenous and endogenous sources, resulting in false-positive and false-negative results. When the immunoassay results do not appear to fit the clinical picture, it becomes a great challenge to a clinical biochemist, alarms clinicians and confounds immunoassay manufacturers. Sometimes, these results can mislead or miss a diagnosis, resulting in unnecessary investigations and mental trauma to the patient and families. Hence, it is very important for one to be aware of the limitations of this immunoassay, to have knowledge about them and to take necessary actions or precautions to get the right result. There is no single procedure that can rule out all interferences. Furthermore, it is difficult for the laboratorians to identify antibody interference with immunoassay, and thus, physicians should be encouraged to communicate specifically with the laboratory about discordance between results and clinical findings. If there is any suspicion of discordance between the clinical and the laboratory data, an attempt should be made to reconcile the difference. Procedures should be put in place when interference is suspected. Constant communication is required between physician and laboratory about unexpected immunoassay results. Manufacturers can also be communicated to identify the presence of interfering antibody.