A unique case of red blood cell agglutination reaction on glass surface in otherwise normal sample

Autoimmune hemolytic anemias (AIHAs) are not very common, and autoimmunity is an important cause of hemolytic anemia, especially in female population. Some primary AIHAs are cold or warm agglutinin mediated anemia. Autoimmune reaction leads to macrophage activation as well as conversion of normal RBCs into spherocytes leading to their destruction and causing hemolysis leading to anemia. Rarely autoimmune phenomena can lead to agglutination however Cold agglutinin disease or Warm agglutinin disease have specific tests which are diagnostic for them. Here, we highlight a known case of Grave's disease who was admitted to the emergency and on sampling the peripheral blood repeated agglutination/clumping of RBCs occurred on glass surface but nothing happened in the plastic EDTA tube. This to the authors was extremely puzzling phenomena which occurred even on repeat sample for the case, Hence the authors warranted a need to discuss this.