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Not all anti-parietal cell antibody tests are equal for diagnosing pernicious anemia

  • Valentin Lacombe EMAIL logo and Geoffrey Urbanski ORCID logo
Published/Copyright: September 5, 2025
Clinical Chemistry and Laboratory Medicine (CCLM)
From the journal Clinical Chemistry and Laboratory Medicine (CCLM) Volume 64 Issue 1

Abstract

Objectives

Pernicious anemia (PA) is a common cause of vitamin B12 deficiency and requires a robust diagnosis to guide lifelong treatment. Anti-parietal cell antibodies (APCA) are frequently used as a diagnostic marker, but their poor specificity raises concerns about overdiagnosis, particularly in patients lacking the more specific but less sensitive anti-intrinsic factor antibodies (IFA). We compared the diagnostic performance of two APCA detection methods: indirect immunofluorescence (IIF) and immunodot assay.

Methods

We prospectively enrolled patients with B12 deficiency and APCA positivity without IFA. PA diagnosis was adjudicated by blinded expert based on histology and response to oral B12. Patients were classified as true PA (APCA-PA), false positive (APCA-FP), or undetermined. Only APCA-PA and APCA-FP cases were analyzed.

Results

Among 56 included patients, 19 were classified as APCA-PA and compared to 24 APCA-FP. APCA immunodot assay was positive in 19/19 APCA-PA vs. 23/24 APCA-FP (p>0.99), while APCA IIF was positive in 13/19 APCA-PA vs. 2/24 APCA-FP (p<0.001), with higher IIF titers among APCA-PA (p<0.001). Only IIF positivity was significantly associated with PA (68.4 % vs. 8.3 %, p<0.001), with 92 % specificity. This association was confirmed in multivariate analysis (OR 37.1 [95 % CI: 6.1–439.4]). APCA IIF titer was also associated with PA diagnosis (AUC 0.82 [95 % CI: 0.68–0.96]), and titer ≥1:80 further improved specificity to 96 %.

Conclusions

IIF is more specific than immunodot for PA diagnosis, and its result should prevail over immunodot when deciding whether to perform EGD, when EGD is not feasible, and when establishing the diagnosis if biopsies are inconclusive.

Keywords: pernicious anemia; vitamin B12; diagnostic biomarkers; indirect fluorescent antibody technique; immunodot
Corresponding author: Valentin Lacombe, MD, MSc, PhD Student, Service de Médecine interne et polyvalente, Centre Hospitalier du Haut-Anjou, Château-Gontier, France; Université Angers, Equipe MitoLab, Unité MITOVASC, UMR CNRS 6015, Inserm U1083, SFR ICAT, F-49000, Angers, France; and Service de Médecine interne et immunologie clinique, Centre Hospitalier Universitaire d’Angers, Angers, France, E-mail:

Funding source: Centre Hospitalier Universitaire d’Angers

Award Identifier / Grant number: Appel d’offre interne (2020)

  1. Research ethics: This study was approved by the Angers University Hospital Bioethics Committee (2018/63), and was study was conducted in accordance with the Declaration of Helsinki (as revised in 2013).

  2. Informed consent: All participants provided written informed consent.

  3. Author contributions: VL: conceptualization, methodology, investigation, data curation, formal analysis, writing – original draft. GU: conceptualization, methodology, funding acquisition, supervision, formal analysis, writing – review and editing. All authors have accepted responsibility for the entire content of this manuscript and approved its submission.

  4. Use of Large Language Models, AI and Machine Learning Tools: LLM was used solely to improve the clarity and accuracy of the English language in the writing of this manuscript. No LLM or deep learning tool was involved in the generation, analysis, or interpretation of any data presented in the study.

  5. Conflict of interest: The authors state no conflict of interest.

  6. Research funding: This study received funding support from the University Hospital of Angers.

  7. Data availability: The data that support the findings of this study are available from the corresponding author (VL) upon reasonable request.

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Received: 2025-06-03
Accepted: 2025-08-29
Published Online: 2025-09-05
Published in Print: 2026-01-27

© 2025 Walter de Gruyter GmbH, Berlin/Boston

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  2. Editorial
  3. Keeping pace with patient safety by developing and qualifying higher-order reference measurement procedures for laboratory measurement standardization
  4. Review
  5. The role of AI in pre-analytical phase – use cases
  6. Opinion Paper
  7. Total laboratory automation: fit for its intended purposes?
  8. Guidelines and Recommendations
  9. EFLM checklist for the assessment of AI/ML studies in laboratory medicine: enhancing general medical AI frameworks for laboratory-specific applications
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  31. Comparison of seven different enzymatic methods for serum glycated albumin in pregnant women: a multicenter study
  32. Infectious Diseases
  33. Comparative analysis of monocyte distribution width alterations in Escherichia coli sepsis: insights from in vivo and ex vivo models
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  35. Annual Reviewer Acknowledgment
  36. Reviewer Acknowledgment
  37. Letters to the Editor
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  39. Are vitamins A and E results truly traceable and clinically useful? A practical and critical inquiry
  40. Tafasitamab interference in immunofixation electrophoresis
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https://doi.org/10.1515/cclm-2025-0671
Keywords for this article
pernicious anemia; vitamin B12; diagnostic biomarkers; indirect fluorescent antibody technique; immunodot

Articles in the same Issue

  1. Frontmatter
  2. Editorial
  3. Keeping pace with patient safety by developing and qualifying higher-order reference measurement procedures for laboratory measurement standardization
  4. Review
  5. The role of AI in pre-analytical phase – use cases
  6. Opinion Paper
  7. Total laboratory automation: fit for its intended purposes?
  8. Guidelines and Recommendations
  9. EFLM checklist for the assessment of AI/ML studies in laboratory medicine: enhancing general medical AI frameworks for laboratory-specific applications
  10. Candidate Reference Measurement Procedures and Materials
  11. An isotope dilution-liquid chromatography-tandem mass spectrometry-based candidate reference measurement procedure for the quantification of cortisol in human serum and plasma
  12. Isotope dilution-liquid chromatography-tandem mass spectrometry-based candidate reference measurement procedures for the quantification of 24(R),25-dihydroxyvitamin D2 and 24(R),25-dihydroxyvitamin D3 in human serum and plasma
  13. An isotope dilution-liquid chromatography-tandem mass spectrometry-based candidate reference measurement procedure for the quantification of cortisone in human serum and plasma
  14. Candidate reference measurement procedure based on isotope dilution-two dimensional-liquid chromatography-tandem mass spectrometry for the quantification of androstenedione in human serum and plasma
  15. An isotope dilution-liquid chromatography-tandem mass spectrometry-based candidate reference measurement procedure for the quantification of 17β-estradiol in human serum and plasma
  16. Isotope dilution-liquid chromatography-tandem mass spectrometry-based candidate reference measurement procedures for the quantification of total and free phenytoin in human serum and plasma
  17. An isotope dilution-liquid chromatography-tandem mass spectrometry based candidate reference measurement procedure for the simultaneous quantification of 25-hydroxyvitamin D3 and 25-hydroxyvitamin D2 in human serum and plasma
  18. General Clinical Chemistry and Laboratory Medicine
  19. Quality assurance using patient split samples: recommendations for primary healthcare laboratories
  20. Age distorts the interpretation of FIB-4
  21. Not all anti-parietal cell antibody tests are equal for diagnosing pernicious anemia
  22. Impact of renal and hepatic function on dihydropyrimidine dehydrogenase phenotype assessed by enzyme activity in peripheral blood mononuclear cells and uracilemia
  23. Fecal leukocyte esterase levels predict endoscopic severity as an alternative biomarker in inflammatory bowel disease
  24. Cancer Diagnostics
  25. CA-125 glycovariant assays enhance diagnostic sensitivity in the detection of epithelial ovarian cancer
  26. Cardiovascular Diseases
  27. Defining the analytical characteristics of a novel high-sensitivity point-of-care troponin I assay in its intended clinical environment
  28. An automatic chemiluminescence immunoassay for a novel biomarker NT-IGFBP-4: analytical performance and clinical relevance in heart failure
  29. Analysis of total cholesterol results measured in the initial period of the Croatian screening program for familial hypercholesterolemia: a pilot study
  30. Diabetes
  31. Comparison of seven different enzymatic methods for serum glycated albumin in pregnant women: a multicenter study
  32. Infectious Diseases
  33. Comparative analysis of monocyte distribution width alterations in Escherichia coli sepsis: insights from in vivo and ex vivo models
  34. Proadrenomedullin for prediction of early and mid-term mortality in patients hospitalized for community-acquired pneumonia
  35. Annual Reviewer Acknowledgment
  36. Reviewer Acknowledgment
  37. Letters to the Editor
  38. Biological variation of serum Golgi protein 73 concentrations
  39. Are vitamins A and E results truly traceable and clinically useful? A practical and critical inquiry
  40. Tafasitamab interference in immunofixation electrophoresis
  41. Improvement in the turnaround time of PTH(1–84) as part of the intraoperative PTH monitoring for parathyroidectomy
  42. Rethinking the use of “one-way ANOVA” in CLSI EP15-A3 – a call for terminological precision and methodological clarity
  43. Toxic beauty: acute kidney injury triggered by hair-straightening treatment
  44. Congress Abstracts
  45. 57th National Congress of the Italian Society of Clinical Biochemistry and Clinical Molecular Biology (SIBioC – Laboratory Medicine)
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