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Wednesday, 30 June 2021

THE IMPORTANCE OF CLINICAL LABORATORY IN THE EARLY DETECTION OF CRYOAGGLUTININS

Written by Ángel Pérez Arribas | Luz del Mar Rivas Chacón | Carmen Blanco Barros

Figure 1. A peripheral blood smear with presence of red cells agglutination and some segmented neutrophils.

A 66-year-old male case with lung disease and atrial fibrillation, who is admitted due to coronavirus disease 2019 (COVID-19), however the discovery of cold agglutinins in blood smears by the clinical laboratory’s specialists, raises up suspicions of a possible superinfection by Mycoplasma pneumoniae, which was treated with antibiotics.

Patient come to the emergency room due to a week-long dyspnoea with minimal exertion and a dry cough without fever. Given the COVID-19 pandemic situation, an analysis with RT-PCR, biochemistry, blood count, and coagulation is requested. Table 1 shows the most relevant analytical data.
imagen2Table 1. Relevant biochemistry and blood count data at first analysis, required on Cobas 8000 and Sysmex XN1000 autoanalyzers

The high results obtained for some biochemical markers, such as the elevation of LDH, CRP, Ferritin and D-Dimer as well as the decrease in lymphocytes, suggest a possible COVID-19 infection, which is confirmed with positive RT-PCR and then, it is decided to get the patient into the Pneumology Service. In addition, low blood cell and haematocrit levels, as well as high levels of mean corpuscular haemoglobin (MCH), draw attention to the blood count. A peripheral blood smear is performed, where red blood cell agglutination is observed (Figure 1). Subsequently, the blood count is repeated after a sample incubation at 37ºC for half hour, obtaining the results in Table 2. Because of the significant change in the number of red blood cells and, therefore, in all the calculations associated with the red series, the laboratory decides to expand the cold agglutinins study.

imagen3v2Table 2. Hemogram data corrected after incubation at 37ºC, obtained by Sysmex XN1000 autoanalyzer

The result of the study show the presence of cold agglutinins with anti-I specificity at 1/2048. In subsequent tests, a significant decrease in the haemoglobin is observed. The appearance of hematomas, together with the clinical symptoms ofrespiratory infection and the presence of cold agglutinins, end in cover the patient with azithromycin. Cold agglutinins associated with respiratory infection by Mycoplasma pneumoniae has a frequency of 25-35%, as well as a habitual anti-I specificity. In the following weeks, a significant improvement is observed in the anaemia and the patient's respiratory symptoms.

The work of the laboratory should be highlighted, since the interpretation of the hemogram and the blood smear, with the patient's clinic and the other complementary tests, ended in an effectively diagnosed infection by Mycoplasma pneumoniae. It is clear that the proper diagnosis and management of the patient has been possible thanks to the close communication between the laboratory and the other services of the hospital.

REFERENCE
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  2. Moreno LP, Londono D. Hiperleucocitosis asociada a leucostasis pulmonar y cerebral en leucemia mieloide aguda. Acta Med Colomb. 2011; 36 (2):90-92.
  3. Shiber JR, Fines RE. Cerebral hemorrhage due to hyperleucocytosis. Journal of Emergency medicine. 2008; 40(6):674-677.
  4. González AI, Rebolledo AM, Fonseca DL. Paciente con livideces en miembros inferiores y leucemia mieloide aguda. 2007; 15(3):232-234.
 

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