Support the diagnosis of primary atypical pneumonia (Mycoplasma pneumoniae), hemolytic anemia, cirrhosis, Raynaud's disease, some viral diseases, and infectious diseases such as staphylococcemia and influenza. May also occur in pregnancy. A fourfold rising and falling titer is found in primary atypical pneumonia (PAP); 55% of patients with PAP have rising titers. Ninety percent of these are severely affected or have prolonged illness.
Titer less than 1:40
False negatives may occur if serum is refrigerated on the clot. Only half of patients with M. pneumoniae infection will have a positive test. Sensitivity: 1:10
- Agglutinins, Cold
- COLD AGGLUTININS
Collect specimen in a red top tube; do not use SST tube. Maintain specimen at room temperature. In the laboratory, process as follows: 1) Place specimen in 37 degrees C waterbath or incubator for 30 minutes and allow to clot. 2) After 30 minute incubation at 37 degrees C, centrifuge specimen at 2000 rpm for 5 minutes. 3) Aliquot serum into a plastic vial and refrigerate. 4) Indicate on requisition or manifest that the specimen was incubated at 37 degrees C for 30 minutes. If specimen processing equipment is not available, the patient should have the specimen collected at an Mlabs Blood Drawing station.
Store intact red top tube specimen at room temperature for no longer than 24 hours.
The most common cause of elevated cold agglutinins in high titer is secondary to an infection with Mycoplasma pneumoniae. Cold agglutinins are usually IgM autoantibodies directed against the Ii antigens of human RBCs. These antibodies may be found in patients with cold agglutinin disease or may occur transiently following a number of acute infectious illnesses. Cold agglutinins of cold agglutinin disease are usually monoclonal IgM Kappa. Cold antibodies of IgG, IgA, or IgM type directed against i antigens may be found in infectious mono. Antibodies reacting closer to physiologic temperatures are more likely to be clinically important. In PAP, cold agglutinins are demonstrated one week after onset; the titer increases in 8 to 10 days, peaks at 12 to 25 days, and rapidly falls after day 30. Antibiotic therapy may interfere with antibody formation.