What does a positive DAT indicate?

A positive DAT indicates immunoglobulin (IgG) or complement (C3) bound to red blood cell surfaces. IgG alone or IgG+C3: warm AIHA (IgG antibodies active at 37°C, often react with Rh antigens). C3 alone: cold agglutinin disease (IgM antibody activating complement at cold temperatures).

What are causes of a positive DAT without hemolysis?

Up to 0.1% of healthy blood donors and 1–8% of hospitalized patients have a positive DAT without hemolysis. Causes include drug coating (penicillin, cephalosporins), hypergammaglobulinemia, and alloantibodies from prior transfusion or pregnancy.

How is warm AIHA treated?

First-line: prednisolone 1 mg/kg/day. Second-line: rituximab, splenectomy (for IgG/Rh mediated), or mycophenolate. Cold agglutinin disease: rituximab ± bendamustine is now preferred over steroids.

Coombs Test (DAT) Interpretation for Hemolytic Anemia

Interprets the Direct Antiglobulin Test (DAT/Coombs test) results for autoimmune and alloimmune hemolytic anemia. IgG+C3d: warm AIHA; C3d alone: cold agglutinin disease; IgG alone: drug-induced or warm AIHA. Includes indirect Coombs (IAT) interpretation for pre-transfusion testing.

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Frequently Asked Questions

What does a positive DAT indicate?

What are causes of a positive DAT without hemolysis?

How is warm AIHA treated?