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Clinical consequences of erroneous laboratory results that went unnoticed for 10 days
  1. Tze Ping Loh1,
  2. Lennie Chua Lee2,
  3. Sunil Kumar Sethi1,
  4. Doddabele Srinivasa Deepak2
  1. 1Department of Laboratory Medicine, National University Hospital, Singapore
  2. 2Division of Endocrinology, Department of Medicine, National University Hospital, Singapore
  1. Correspondence to Dr Tze Ping Loh, Department of Laboratory Medicine, National University Hospital, 5 Lower Kent Ridge Road, Singapore 119074; lohtp{at}

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Erroneous laboratory results can adversely affect medical decisions. While the prevalence of laboratory errors has been well documented,1 their consequences, particularly when they go unnoticed, are less well reported. We describe the clinical consequences of a series of falsely elevated laboratory results that went unnoticed for 10 days.

On 20 June 2012, an endocrinologist alerted the laboratory to possible spurious results after noticing extremely high insulin-like growth factor-1 (IGF-1) concentrations in two clinically asymptomatic patients. The ensuing investigations revealed an error in the analyser (Immulite 2000, Siemens, Surrey, UK) that performed five endocrine tests, including IGF-1, and affected all results reported on 11 June. The error eluded the internal quality control (QC) testing performed routinely prior to patient sample analysis.

All erroneous results (n=63) were unknowingly reported. Retesting of all specimens belonging to 49 patients revealed 2.1- to >108-fold reductions in their results (see online supplementary table S1). The ranges of the erroneous results and the correct values (in parentheses), respectively, were: adrenocorticotrophic hormone (ACTH, n=10), 15.3–132 pmol/l (<1.11–36.6); anti-thyroglobulin antibodies, 67– >3000 IU/ml (n=15, <20–830); anti-thyroid peroxidase antibodies, 37– >1000 IU/ml (n=7, <10–876); growth hormone, 2.12–188 µg/l (n=10, 0.35–9.63); IGF-1 603–2263 ng/ml (n=21, 54–292). All ordering physicians were immediately notified of the amended results. The engineers of the manufacturer were immediately brought in to conduct an extensive investigation, which included checking for reagent/probe/tubing contamination, reagent …

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  • Contributors TPL conceived, collected the data and co-wrote the first draft. LCL and DSD managed the patient. DSD co-wrote the first draft. SKS critically reviewed and revised the final draft.

  • Competing interests None.

  • Ethics approval Domain Specific Review Board of the National University Hospital, Singapore.

  • Provenance and peer review Not commissioned; externally peer reviewed.