LAUSR

INTRODUCTION The direct antiglobulin test (DAT) or Coombs test is the cornerstone of the diagnosis of autoimmune hemolytic anemia (AIHA). It can be performed by several methods with different sensitivity and specificity and enables the distinction of warm, cold, and mixed forms, which require different therapies. AREAS COVERED The review describes the different DAT methods, including the tube test with monospecific antisera, microcolumn and solid phase methods that are routinely accessible in most laboratories. Additional investigations include the use of cold washes and low ionic salt solutions, the identification of auto-Ab specificity and thermal range, the study of the eluate, and the Donath-Landsteiner test, available in most reference laboratories. Experimental techniques are the dual-DAT, flow cytometry, ELISA, immuno-radiometric assay, and mitogen-stimulated DAT, which may help the diagnosis of DAT-negative AIHAs, a clinical challenge with delayed diagnosis and possible improper therapy. Further diagnostic challenges include the correct interpretation of hemolytic markers, the infectious and thrombotic complications, and the possible underlying conditions (lymphoproliferative disorders, immunodeficiencies, neoplasms, transplants, and drugs). EXPERT OPINION These diagnostic challenges may be overcome by a 'hub' and 'spoke' organization among laboratories, a clinical validation of experimental techniques, and a continuous dialogue between clinicians and immune-hematologic laboratory experts.