Cold Agglutinin Test

Clinical Background:

Request Reasons: Cold Agglutinin Disease (CAD), Cold-induced Autoimmune Haemolytic Anaemia, Infective triggers (e.g. influenza, Mycoplasma pneumonia, mononucleosis, and HIV), lymphoproliterative di...

Requested under haematological consultant guidance. More specialised investigations such as Cold Agglutinin Titre, DAT and Donath-Landsteiner may be associated with the initial Cold Agglutinin test. Cold agglutinins are autoantibodies that react with antigens on the red blood cell surface. They may induce complement-mediated haemolysis and agglutination (clumping) of red cells. Cold agglutinins exert their pathological effects via haemolysis and red cell destruction in the reticuloendothelial system, predominantly in the liver, or by agglutination of red cells in peripheral cold-exposed vessels leading to vaso-occlusion. Cold agglutinins derive their name from the fact that they show maximal activity at temperatures lower than normal body temperature. They are present in low titres in healthy individuals, but may be associated with a range of disease states. The cold agglutinin-induced diseases are classified into primary or idiopathic form, and secondary form, caused by the existence of an underlying disease state. Primary cold agglutinins are monoclonal; secondary ones may be either polyclonal or monoclonal. Cold agglutinins are not responsible for episodes of haemolysis of transfused red blood cells (Transfusion Reaction) or for episodes of haemolytic disease of the fetus and newborn (HDFN). The cold agglutinin test is performed to detect the presence of cold reacting antibodies in blood. If detected using a screen at 1/32 dilution an extended cold agglutinin titre will be performed.

Discipline:

Transfusion

Transfusion
Specimen Container Adult:

6mL K2 EDTA (Pink Top)

6mL K2 EDTA (Pink Top)
Specimen Container Paediatric:

6mL K2 EDTA (Pink Top)

6mL K2 EDTA (Pink Top)
Minimum Volume Adult:

6mL

6mL
Minimum Volume Paediatric:

2mL

2mL
Special Requirement:

Sample must be HANDWRITTEN and contain the patient's details.

Sample must be HANDWRITTEN and contain the patient's details.
Sample Stability:

Short term storage: Must be maintained at 37

Short term storage: Must be maintained at 37
Transport Requirements:

Sample should be transported to Laboratory Medicine Reception via GP courier, hospital air-tube system or hand delivered to maintain storage conditions. Samples must not be subjected to extreme hot...

Sample should be transported to Laboratory Medicine Reception via GP courier, hospital air-tube system or hand delivered to maintain storage conditions. Samples must not be subjected to extreme hot or cold conditions prior to testing.
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Add On Test:

Requested as required by the laboratory. Full Titre

All urgent add ons via telephone must be confirmed via email to the appropriate email address

tnu-tr.bloodsciencesadditions@nhs.net (internal)

tn...

Requested as required by the laboratory. Full Titre

All urgent add ons via telephone must be confirmed via email to the appropriate email address

tnu-tr.bloodsciencesadditions@nhs.net (internal)

tnu-tr.bloodsciencesadditions@nhs.net (external)
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Interpretation:

The titre is the reciprocal of the highest plasma dilution at which macroscopic agglutination is observed. A typical clinically significant titre is when agglutination at 4°C with a 1/64 dilution o...

The titre is the reciprocal of the highest plasma dilution at which macroscopic agglutination is observed. A typical clinically significant titre is when agglutination at 4°C with a 1/64 dilution or greater of the patient’s plasma against O cells is identified. Cold-reactive auto-agglutinins rarely occurs unless the titre is >1000. Titres below 1000 may be obtained when the autoantibody has a different specificity (e.g. anti-I), or if the cold agglutinin is of the less common low-titre, high-thermal-amplitude type. Test should be performed regularly, because an increase in titre throughout the duration of the illness is of greater significance than a positive result on a single specimen. A fourfold or greater rise in the titre of cold agglutinins is suggestive of a recent Mycoplasma pneumonia infection.
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Factors Affecting Result:

Key factors affecting the result: • Specimen not received in laboratory within a temperature controlled flask/container or maintained at 37°C prior to separation to avoid in-vitro autoadsorption. •...

Key factors affecting the result: • Specimen not received in laboratory within a temperature controlled flask/container or maintained at 37°C prior to separation to avoid in-vitro autoadsorption. • An EDTA anticoagulated specimen not maintained at 37°C can be used in extreme circumstances if pre-warmed to 37°C and maintained for at least 30 minutes to release the autoabsorbed antibody back into the plasma prior to separation and testing. However, this is not always successful. • Dispensing incorrect quantities will adversely affect the outcome of this test, resulting in a falsely increased or decreased titre. • The technique for reading the test to detect agglutination is critical. Weak or fragile agglutinates may break apart, resulting in a false negative result and a false decrease in the reported titre. • The reaction between a true cold agglutinin and the red blood cells is reversible. To prove the presence of a true cold agglutinin, all tests showing agglutination at 4°C must revert to negative after incubation at 37°C for 15 - 30 minutes. If agglutination remains, the antibody involved is not a true cold agglutinin.
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Referenced Documents:

4/1/15

4/1/15
Routine Contact Name:

Section Leader:
Routine Telephone:

Freeman: 0191 213 7849
RVI: 0191 282 4335

Freeman: 0191 213 7849
RVI: 0191 282 4335
Specialist Test:

Yes

Yes
Specialist Contact Name:

transfusion manager

transfusion manager
Specialist Telephone:

0192 213 9169

0192 213 9169

Cold Agglutinin Test

Clinical Background:

Test Details

Availability:

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