TY - JOUR
AU - Weinzierl, Elizabeth P
AB - Case Description A 12-year-old female presented to the emergency department with altered mental status. Due to past medical history, a CO-oximetry panel was ordered, which showed methemoglobin (MetHb) of 13.9% (reference interval 0.4–1.5%) from a Radiometer ABL825 and 6.9% from a Radiometer ABL90, but both analyses were flagged with an error flag. A peripheral blood sample from the patient was then analyzed by HPLC (Fig. 1). Fig. 1 Open in new tabDownload slide HPLC chromatogram of the patient’s peripheral blood performed on a Bio-Rad Variant II. In addition to the unremarkable HbA and HbA2 peaks, there is an abnormal peak eluting at 5.10 min in the C window representing 10.5% of the total area, as indicated by the arrow. Fig. 1 Open in new tabDownload slide HPLC chromatogram of the patient’s peripheral blood performed on a Bio-Rad Variant II. In addition to the unremarkable HbA and HbA2 peaks, there is an abnormal peak eluting at 5.10 min in the C window representing 10.5% of the total area, as indicated by the arrow. Questions What are the main causes of methemoglobinemia? How is methemoglobinemia usually detected in the laboratory? What is the probable cause of the CO-oximetry error messages? The answers are below. Answers Methemoglobinemia can be caused by exposure to oxidizing chemicals, hereditary, or idiopathic etiologies (1,). MetHb is detected by CO-oximetry. The patient has hemoglobin M-Saskatoon, which causes chronic methemoglobinemia and was originally diagnosed by DNA sequencing. The Radiometer error messages probably resulted from the different absorbance spectrum of this variant (2,). The different Radiometer analyzers use different wavelengths (256  vs. 128  total wavelengths), which may account for the discrepancies. This variant can be seen by HPLC (2, 3). Author Contributions All authors confirmed they have contributed to the intellectual content of this paper and have met the following 4 requirements: (a) significant contributions to the conception and design, acquisition of data, or analysis and interpretation of data; (b) drafting or revising the article for intellectual content; (c) final approval of the published article; and (d) agreement to be accountable for all aspects of the article thus ensuring that questions related to the accuracy or integrity of any part of the article are appropriately investigated and resolved. Authors’ Disclosures or Potential Conflicts of Interest Upon manuscript submission, all authors completed the author disclosure form. Disclosures and/or potential conflicts of interest: Employment or Leadership V. Leung-Pineda, Children’s Healthcare of Atlanta. Consultant or Advisory Role None declared. Stock Ownership None declared. Honoraria None declared. Research Funding None declared. Expert Testimony None declared. Patents None declared. References 1 Haymond S , Cariappa R, Eby CS, Scott MG. Laboratory assessment of oxygenation in methemoglobinemia . Clin Chem 2005 ; 51 : 434 . Google Scholar Crossref Search ADS PubMed WorldCat 2 Hoyer J , Kroft S. Color atlas of hemoglobin disorders: a compendium based on proficiency testing. College of American Pathologists; 2003 . 3 Garcia-Morin M , Manrique-Martin G, Ropero P, Bardon-Cancho E, Garcia-Roves R, Belendez C, Cela E. Hb M-Saskatoon: an unusual cause of cyanosis in a Spanish child . Pediatr Hematol Oncol J 2019 ; 4 : 23 – 6 . Google Scholar Crossref Search ADS WorldCat © American Association for Clinical Chemistry 2020. All rights reserved. For permissions, please email: journals.permissions@oup.com. This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model)
TI - Is It Really Methemoglobin?
JF - Clinical Chemistry
DO - 10.1093/clinchem/hvaa062
DA - 2020-08-01
UR - https://www.deepdyve.com/lp/oxford-university-press/is-it-really-methemoglobin-AH11Srywg7
SP - 1118
EP - 1119
VL - 66
IS - 8
DP - DeepDyve
ER -