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Test ID: IgM
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IgM
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Useful For
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To detect and to monitor IgM monoclonal gammopathies and IgM-related immune deficiencies.
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Method name and description
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Immunoturbidimetric assay
Immunoturbidimetric assay performed on the Roche cobas c-systems. Anti‑IgM antibodies react with antigen in the sample to form an antigen/antibody complex. Following agglutination, this is measured turbidimetrically. Addition of PEG allows the reaction to progress rapidly to the end point, increases sensitivity, and reduces the risk of samples containing excess antigen producing false negative results.
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Clinical information
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IgM is the first specific antibody to appear in the serum after infection. It is capable of activating complement, thus helping to kill bacteria. This fact is used to advantage in the differential diagnosis of acute and chronic infections by comparing specific IgM and IgG titers. If IgM is prevalent the infection is acute, whereas if IgG predominates the infection is chronic (e.g. rubella, viral hepatitis). Increased polyclonal IgM levels are found in viral, bacterial, and parasitic infections, liver diseases, rheumatoid arthritis, scleroderma, cystic fibrosis and heroin addiction. Monoclonal IgM is increased in Waldenström’s macroglobulinemia. Increased loss of IgM is found in protein‑losing enteropathies and in burns. Decreased synthesis of IgM occurs in congenital and acquired immunodeficiency syndromes. Due to the slow onset of IgM synthesis, the IgM concentration in serum from infants is lower than in that from adults.
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Specimen type / Specimen volume / Specimen container
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Specimen type: Serum, Plasma
Minimum volume of sample: 1 mL
Serum: Plain tube (red or yellow top)
Plasma: Li‑heparin tube
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Collection instructions / Special Precautions / Timing of collection
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Collect blood by standard venipuncture techniques as per specimen requirements. When processing samples in primary tubes (sample collection systems), follow the instructions of the tube manufacturer.
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Storage and transport instructions
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Storage: 2 months at 15 – 25°C
4 months at 2 – 8°C;
6 months at ‑20 °C (± 5 °C)
Transport: 2-25°C
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Specimen Rejection Criteria
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Grossly hemolyzed, icteric and lipemic samples, wrong collection container, insufficient sample.
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Biological reference intervals and clinical decision values
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Patient Sex
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Age
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Reference interval (g/L)
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From
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To
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Male
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0 days
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30 days
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0 – 0.65
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Male
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30 days
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182 days
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0.06 – 0.84
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Male
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182 days
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1 year
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0.15 – 1.17
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Male
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1 year
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3 years
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0.30 -1.46
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Male
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3 years
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6 years
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0.31 – 1.51
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Male
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6 years
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9 years
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0.21 – 1.40
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Male
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9 years
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12 years
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0.27 – 1.51
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Male
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12 years
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15 years
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0.26 -1.84
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Male
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15 years
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18 years
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0.28 – 1.79
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Male
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18 years
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150 years
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0.4 – 2.3
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Female
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0 days
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30 days
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0 – 0.57
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Female
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30 days
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182 days
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0 – 1.27
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Female
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182 days
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1 year
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0 – 1.30
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Female
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1 year
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3 years
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0.35 – 1.84
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Female
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3 years
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6 years
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0.42 – 1.84
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Female
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6 years
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9 years
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0.30 – 1.65
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Female
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9 years
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12 years
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0.42 – 2.11
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Female
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12 years
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15 years
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0.34 – 2.25
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Female
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15 years
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18 years
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0.45 – 2.24
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Female
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18 years
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150 years
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0.4 – 2.3
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Factors affecting test performance and result interpretation
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As with other turbidimetric or nephelometric procedures, this test may not provide accurate results in patients with monoclonal gammopathy, due to individual sample characteristics which can be assessed by electrophoresis.
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Turnaround time / Days and times test performed / Specimen retention time
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Daily (24/7)
Turn-around time:
STAT: 1 hour
Routine: One working day
Specimen Retention: 4 days
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