DAT: IgG negative, complement positive
Donath-Landsteiner test: positive
Diagnosis: Paroxysmal cold hemoglobinuria (PCH)
PCH is a rare autoimmune haemolytic anaemia characterized by the sudden presence of hemoglobinuria, typically after exposure to cold temperatures. PCH usually occur following an infection, when a microorganism triggers the formation of antibodies that cross-react with the P antigen on the red blood cell membrane. Viral infections that can cause PCH include Epstein-Barr virus, cytomegalovirus, measles, mumps, influenza, adenovirus, parvovirus B19, Coxsackie A9, chickenpox, et al. Bacterial infections include syphilis, Haemophilus influenzae and Mycoplasma pneumoniae.
Diagnosis of autoimmune hemolytic anemia (AIHA): Normocytic or macrocytic anemia; Reticulocytosis; Low serum haptoglobin levels; Elevated lactate dehydrogenase (LDH) level; Increased indirect bilirubin level; A positive direct antiglobulin test with a broad-spectrum antibody against immunoglobulin and complement.
When RBC are coated with IgG or IgG plus C3d, the antibody is usually a warm antibody (warm antibody AIHA [WAIHA]). When coated with C3d only, the antibody is often but not always a cold antibody or Donath-Landsteiner antibody.
Peripheral Blood Smear: poikilocytosis, spherocytes, polychromasia, nucleated RBCs, mild agglutination of the RBCs can occur. Erythrophagocytosis, esp., by neutrophils.
Urinalysis: presence of free hemoglobin or methemoglobin. Hematuria is generally absent
The Donath-Landsteiner test
The procedure involves incubating three specimens: (1) the patient's serum, (2) a mix of patient's and normal serum, and (3) normal serum with P-positive RBCs at 4° C. The sample is heated to 37° C, followed by visual analysis of the serum for hemolysis, which is indicative of a positive reaction (see image below). If the D-L antibody is present, samples 1 and 2 should be positive. As negative controls, the three samples are replicated at testing conditions in which temperature is maintained at 4°C and 37°C throughout.
Differential Diagnoses: Cold Agglutinin Disease; Drug-Induced Hemolysis; Malaria; Paroxysmal Nocturnal Hemoglobinuria; Transfusion Reactions
Treatment: supportive care and avoidance of cold exposure.
Prognosis: recover completely. Chronic PCH also occurs.
Donath-Landsteiner test: positive
Diagnosis: Paroxysmal cold hemoglobinuria (PCH)
PCH is a rare autoimmune haemolytic anaemia characterized by the sudden presence of hemoglobinuria, typically after exposure to cold temperatures. PCH usually occur following an infection, when a microorganism triggers the formation of antibodies that cross-react with the P antigen on the red blood cell membrane. Viral infections that can cause PCH include Epstein-Barr virus, cytomegalovirus, measles, mumps, influenza, adenovirus, parvovirus B19, Coxsackie A9, chickenpox, et al. Bacterial infections include syphilis, Haemophilus influenzae and Mycoplasma pneumoniae.
Diagnosis of autoimmune hemolytic anemia (AIHA): Normocytic or macrocytic anemia; Reticulocytosis; Low serum haptoglobin levels; Elevated lactate dehydrogenase (LDH) level; Increased indirect bilirubin level; A positive direct antiglobulin test with a broad-spectrum antibody against immunoglobulin and complement.
When RBC are coated with IgG or IgG plus C3d, the antibody is usually a warm antibody (warm antibody AIHA [WAIHA]). When coated with C3d only, the antibody is often but not always a cold antibody or Donath-Landsteiner antibody.
Peripheral Blood Smear: poikilocytosis, spherocytes, polychromasia, nucleated RBCs, mild agglutination of the RBCs can occur. Erythrophagocytosis, esp., by neutrophils.
Urinalysis: presence of free hemoglobin or methemoglobin. Hematuria is generally absent
The Donath-Landsteiner test
The procedure involves incubating three specimens: (1) the patient's serum, (2) a mix of patient's and normal serum, and (3) normal serum with P-positive RBCs at 4° C. The sample is heated to 37° C, followed by visual analysis of the serum for hemolysis, which is indicative of a positive reaction (see image below). If the D-L antibody is present, samples 1 and 2 should be positive. As negative controls, the three samples are replicated at testing conditions in which temperature is maintained at 4°C and 37°C throughout.
Differential Diagnoses: Cold Agglutinin Disease; Drug-Induced Hemolysis; Malaria; Paroxysmal Nocturnal Hemoglobinuria; Transfusion Reactions
Treatment: supportive care and avoidance of cold exposure.
Prognosis: recover completely. Chronic PCH also occurs.