DISCORDANCES BETWEEN HEMATOCRIT AND HEMOGLOBIN

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SESSION TITLE: Wednesday Fellows Case Report Posters SESSION TYPE: Fellow Case Report Posters PRESENTED ON: 10/23/2019 09:45 AM - 10:45 AM INTRODUCTION: Hemoglobin (Hg) and hematocrit (Hct) are independent parameters observed to maintain an approximate 1:3 ratio. The ratio may vary if red blood cells (RBC) are abnormal, or appeared altered due to technical factors. Here, we present a case of Hg-Hct discordance, likely due to cold agglutinins, and describe complications in the management. CASE PRESENTATION: A 65-year-old male, recently diagnosed with Waldenstrom’s Macroglobulinemia (WM), was admitted in January with complaints of dyspnea and blurry vision. Initial labs showed Hg 18.8 g/dL, Hct 24%, elevated total protein (TP), IgM, and serum viscosity. The peripheral smear demonstrated mixed hypochromasia and hyperchromasia, polychromasia, and rouleaux formation. Imaging revealed mediastinal and hilar adenopathy, and splenomegaly with infarcts. He received plasmapheresis (PP) for hyperviscosity syndrome with improvement in his symptoms, TP and IgM. His hospital course was complicated by pneumonia. He improved following a course of antibiotics and repeat PP, and was discharged following initiation of chemo-immunotherapy.Discordance between Hg and Hct was observed. Correction of Hg and Hct from falsely elevated or reduced values, and restoration of the Hg-Hct ratio and mean cell hemoglobin concentration (MCHC), was seen after sample reprocessing at 37 degrees C or saline replacement, suggesting the presence of agglutinins. Progressive decline in the corrected Hg and Hct was also observed, which was partially masked by uncorrected values. RBC transfusion was guided by corrected Hg and Hct values, as uncorrected values met transfusion thresholds for one parameter but not the other. DISCUSSION: Automatic cell counters measure multiple parameters to determine Hg and Hct. For example, Hg is measured by spectrophotometry or light scatter, or calculated from other RBC indices, Hct is calculated from mean cell volume and RBC count or Hg, RBC count is measured by flow cytometry or electrical impedance. Cold agglutinins (CA) are autoantibodies that bind to RBC surface antigens below normal core body temperature, resulting in RBC agglutination. CA can cause hyperviscosity syndrome on exposure to cold, and hemolysis with cold exposure or exacerbating conditions such as trauma or infection. RBC agglutination can interfere with measurement of RBC count and other indices including mean cell volume and MCHC, and therefore measurement of Hg and Hct. Effects of CA depend on the antibody titer and thermal amplitude. The presence of CA can be measured by titer, or suggested by peripheral smear or CBC review at 37 degrees C. Recognition of the Hg-Hct discordance facilitated recognition of CA and underlying hemolysis, and guided appropriate RBC transfusion. CONCLUSIONS: Clinicians should consider CBC results cautiously, and are encouraged to be aware of the method of Hg and Hct determination, and to identify and understand sources of error in diagnostic testing. Reference #1: Ercan, Serif et al. “70-year old female patient with mismatch between hematocrit and hemoglobin values: the effects of cold agglutinin on complete blood count” Biochemia medica vol. 24,3 391-5. 15 Oct. 2014. Reference #2: Yasar NE, Ozgenc A, Bolayirli IM, Adiguzel M, Konukoglu D. Unexpected laboratory results in cold agglutinin disease. Int J Med Biochem. 2018;1:40–3. Reference #3: Berentsen S, Beiske K, Tiønnfjord GE. Diagnosis and treatment of cold agglutinin mediated autoimmune hemolytic anemia. Blood Rev. 2012;26:107–15. DISCLOSURES: No relevant relationships by Obed Adarkwah, source=Web Response No relevant relationships by Mona Alipour, source=Web Response No relevant relationships by Nabil Mesiha, source=Web Response No relevant relationships by Reza Samad, source=Web Response No relevant relationships by jad sargi, source=Web Response No relevant relationships by Akshaykumar Vachhani, source=Web Response