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UW Health SMPH
American Family Children's Hospital

UW Hospital and Clinics Lab Test Directory

Test Name: IgM

Test Code(s): IGM / XGAM3

CPT Code(s): 82784

Methodology: Nephelometry

Clinical Significance: Measurement of IgM aids in the diagnosis of immunoglobulin disorders, multiple myeloma, macroglobulinemia and hypergammaglobulinemic states.

Days Performed: Daily, 24 hours.

Turnaround Time: Stat: 1 hour.
Routine: Up to 4 hours.

Specimen Requirements

Specimen: Blood

Collection Instructions: If there is the possibility that the patient has a cryoprotein, specimen MUST BE KEPT WARM UNTIL AFTER TESTING IS COMPLETE. Indicate specimen is to be drawn warm.

Collection Container: Preferred: Red cap with yellow ring (SST)
Also Acceptable: Red top

Collection Volume: Preferred: 3 mL
Pediatrics: 1 mL

Sample Analyzed: Serum

Volume Required: Preferred: 1 mL
Pediatrics: 0.3 mL

Specimen Processing: Centrifuge within 2 hours of draw. Transfer cell-free serum to plastic vial.  Refrigerate.  Freeze serum if not assayed within 72 hours.

IF THE PATIENT HAS A CRYOPROTEIN, keep blood specimen at 37C during entire processing procedure. Place collection tube in the 37C incubator for two hours. Spin tube at 3000 rpm for 10 minutes at 37C. Remove spun serum to labeled tube and forward to Chemistry Lab.

Specimen Transport: Transport specimen to UWHC Core Laboratory (B4/220). Transport with coolant pack if coming from outreach location. Transport frozen serum aliquot on dry ice to UWHC Core Laboratory (B4/220).

For samples on patients suspected of having a cryoprotein, specimen MUST be processed prior to transport if coming from outreach location. Transport specimens with coolant pack after processing is complete.

Unacceptable Criteria: Grossly hemolyzed specimens are not acceptable.

Stability: Refrigerated: 7 days
Frozen: 3 months at -20 C or below. Note: Avoid repeat freeze and thaw.


Reference Interval:
 Age:  mg/dL
 0 days-11 months  19-193
 12 months-3 years  43-163
 4 years-17 years  48-226
 18 years and up  40-250


Immunoglobulin M

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