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Test ID: IgG
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IgG
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Useful For
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To detect and to monitor IgG monoclonal gammopathies and IgG-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‑IgG 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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Approximately 80 % of serum immunoglobulin is IgG; its main tasks are the defense against microorganisms, direct neutralization of toxins and induction of complement fixation. IgG is the only immunoglobulin that can cross the placental barrier and provide passive immune protection for the fetus and newborn. Polyclonal IgG increases in serum/plasma may be present in systemic lupus erythematosis, chronic liver diseases infectious diseases and cystic fibrosis. Monoclonal IgG increases in IgG‑myeloma.
Decreased synthesis of IgG is found in congenital and acquired immunodeficiency diseases and selective IgG subclass deficiencies, such as Bruton type agammaglobulinemia. Decreased IgG concentrations in serum and plasma are seen in protein-losing enteropathies, nephrotic syndrome and through the skin from burns. Increased IgG metabolism is found in Wiskott-Aldrich syndrome, myotonic dystrophy and with anti‑immunoglobulin antibodies.
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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: 4 months at 15 – 25°C
8 months at 2 – 8°C;
8 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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1.97 – 8.33
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Male
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30 days
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182 days
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1.4 – 5.33
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Male
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182 days
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1 year
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1.3 – 8.23
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Male
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1 year
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3 years
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4.13 – 11.12
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Male
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3 years
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6 years
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4.68 – 13.28
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Male
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6 years
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9 years
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5.82 – 14.41
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Male
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9 years
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12 years
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6.85 – 16.2
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Male
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12 years
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15 years
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5.9 – 16
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Male
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15 years
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18 years
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5.22 – 17.03
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Male
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18 years
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150 years
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7 - 16
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Female
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0 days
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30 days
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1.62 – 8.72
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Female
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30 days
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182 days
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3.11 – 6.64
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Female
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182 days
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1 year
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3.25 – 6.47
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Female
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1 year
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3 years
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4.51 – 12.02
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Female
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3 years
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6 years
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5.6 – 13.19
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Female
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6 years
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9 years
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4.85 – 14.73
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Female
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9 years
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12 years
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5.86 – 16.09
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Female
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12 years
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15 years
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7.49 – 16.4
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Female
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15 years
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18 years
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8.04 – 18.17
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Female
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18 years
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150 years
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7 - 16
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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:
Routine: One working day
Specimen Retention: 4 days
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