Laboratory characteristics of direct antiglobulin test-positive anemia in patients with newly diagnosed multiple...

This study retrospectively characterized the laboratory features of direct antiglobulin test (DAT)-positive anemia in newly diagnosed multiple myeloma (MM) and explored associated immunologic alterations to better understand MM-related immune dysregulation.

We enrolled 77 patients with newly diagnosed MM admitted to our hospital between 2021 and 2025. Based on DAT results, patients were assigned to a DAT-positive group (n = 52) or a DAT-negative group (n = 25). Clinical characteristics, laboratory parameters, and peripheral blood T-cell subsets were compared between groups.

Monoclonal immunoglobulin (M protein) isotype distribution was statistically significantly different between groups (P < .001), with immunoglobulin G predominating in the DAT-positive group (88.46%). Compared with the DAT-negative group, DAT-positive patients had lower albumin, sodium, and potassium levels as well as a lower albumin to globulin ratio but higher levels of globulin and ferritin as well as higher absolute lymphocyte counts (all P < .05). Flow cytometric analysis showed increased T-cell-related parameters, particularly CD8-positive T cells, in the DAT-positive group, whereas reduced natural killer-cell and B-cell counts were more common in the DAT-negative group.

The observed laboratory profile suggested a more pronounced state of inflammatory or immune activation and electrolyte disturbances, highlighting the need for improved clinical recognition and detection of potential immune-mediated red blood cell injury, hemolytic predisposition, and related immune abnormalities.