RT Journal Article SR Electronic T1 When laboratory tests can mislead even when they appear plausible JF Clinical Medicine JO Clin Med FD Royal College of Physicians SP 329 OP 332 DO 10.7861/clinmedicine.17-4-329 VO 17 IS 4 A1 Adel AA Ismail YR 2017 UL http://www.rcpjournals.org/content/17/4/329.abstract AB A laboratory test has three phases, pre-analytical, analytical and post-analytical. The purpose of this review is to highlight an issue concerning the analytical phase of one of the most widely deployed groups of in vitro diagnostic tests using a common technology – namely immunoassay.Immunoassay entails an inherently high error rate and, therefore, has the potential for inaccurate and misleading results susceptible to misinterpretation and/or diagnostic misapplication by clinicians. An approach based on Bayesian inference (without mathematics or equations) – illustrated by examples – is presented; this may help clinicians in discerning potentially erroneous results even when they appear plausible and not unreasonable.Essentially, false positive results are most likely to occur when the disease prevalence/incidence is low. False negative results become more prominent when the prevalence/incidence of disease increases. When concern is raised, available follow-up laboratory tests should be initiated to establish with confidence the diagnostic reliability or unreliability of such results.