Turnaround times
The quoted turnaround time is from sample receipt in the laboratory, to results authorisation in the Laboratory Information Management system. The times do not include transport of specimen to the laboratory or the administrative process to print and post/email reports. Service users must allow for transport and reporting time when ordering tests.
Clinical background:
Test to confirm diagnosis of Paroxysmal Cold Haemoglobinuria (PCH). The Donath Landsteiner test should be considered when the Direct Antiglobulin Test (DAT) is positive due to C3 (complement), presence of haemoglobinemia, haemoglobinuria, or both; and no evidence of autoantibody activity in plasma/serum or the eluate made from the DAT positive cells. More commonly associated with acute viral infections in children. PCH can also present as an idiopathic cold haemagglutinin syndrome. The Donath Landsteiner antibody is a biphasic IgG autoantibody with P specificity.
Specimen container paediatric:
6mL clotted sample (no anticoagulant – red top) and 6mL K2 EDTA (pink top)
Specimen container adult:
6mL clotted sample (no anticoagulant – red top) and 6mL K2 EDTA (pink top)
Minimum volume paediatric:
4mL
Minimum volume adult:
6mL
Special requirements:
The Transfusion Laboratory MUST be contacted in advance of sample being taken. Requests for Donath Landsteiner investigations must be authorised by a Consultant Haematologist.
Sample MUST be bagged and transported to the laboratory in a flask warmed to 37oC. This can be provided by the Transfusion laboratory.
A 6mL clotted sample is needed in addition to a 6mL EDTA.
The test can be ordered via EPR PowerChart and taken with the BloodTrack bedside sample labelling system.
The Trust operates a zero tolerance policy. Deviation from Trust Sample Labelling Policy will result in the sample being rejected and a repeat requested.
Sample stability:
Short term storage: Must be maintained at 37°C
Transport requirements:
Sample should be hand delivered to Laboratory Medicine Reception to maintain storage conditions. Samples must not be subjected to extreme hot or cold conditions prior to testing.
Add on test:
Not available as an add on.
Interpretation:
The Donath-Landsteiner assay must only be requested if there is a clinical suspicion of PCH. The test is considered positive when the patient’s serum, with or without added complement, causes haemolysis in the test which was first incubated at 4°C then at 37°C with no haemolysis in the tests maintained at 37°C throughout. A positive test is indicative of Paroxysmal Cold Haemoglobinuria. The autoantibody is transient and can disappear quickly during recovery from the acute illness, rendering a false negative Donath-Landsteiner test. The autoantibody rarely causes RBC agglutination above 4°C, and thus does not interfere with routine pre-transfusion tests. DAT is usually positive for C3, negative for IgG. An eluate is normally negative. The antibody is not detected by routine antibody screen techniques.
Factors affecting result:
Incorrect specimen type received. Specimen not received in laboratory within a temperature controlled flask/container. Specimen not maintained at 37oC prior to separation. Too small a serum volume to complete test. Active complement is needed for demonstration of the antibody.