Test ID: IGGS4 Immunoglobulin Subclass IgG4, Serum
Reporting Name
Immunoglobulin Subclass IgG4, SUseful For
Supporting the diagnosis of IgG4-related disease
Clinical Information
The most abundant immunoglobulin (Ig) isotype in human serum is immunoglobulin G (IgG). IgG immunoglobulins are comprised of 4 subclasses designated IgG1 through IgG4. Of total IgG, approximately 65% is IgG1, 25% is IgG2, 6% is IgG3, and 4% is IgG4. Each IgG subclass contains structurally unique portions of the constant region of the gamma heavy chain.
IgG subclass 4-related disease is a recently recognized syndrome of unknown etiology most often occurring in middle-aged and older men. Several organ systems can be involved and encompasses many previous and newly described diseases such as type1 autoimmune pancreatitis; Mikulicz disease and sclerosing sialadenitis; inflammatory orbital pseudotumor; chronic sclerosing aortitis; Riedel thyroiditis, a subset of Hashimoto thyroiditis; IgG4-related interstitial pneumonitis; and IgG4-related tubulointerstitial nephritis. Each of these entities is characterized by tumor-like swelling of the involved organs with infiltrative, predominately IgG4-positive, plasma cells with accompanying "storiform" fibrosis. In addition, elevated serum concentrations of IgG4 are found in 60% to 70% of patients diagnosed with IgG4-related disease.
The diagnosis of IgG4-related disease requires a tissue biopsy of the affected organ demonstrating the aforementioned histological features. It is recommended that patients suspected of having an IgG4-related disease have their serum IgG4 level measured.
Interpretation
Elevated levels of IgG4 are consistent with, but not diagnostic of, IgG4-related disease.
Report Available
1 to 2 daysDay(s) Performed
Monday through Friday
Clinical Reference
1. Cheuk W, Chan JK: IgG4-related sclerosing disease: a critical appraisal of an evolving clinicopathologic entity. Adv Anat Pathol 2010;17(5):303-332
2. Zen Y, Nakanuma Y: IgG4-related disease: a cross-sectional study of 114 cases. Am J Surg Pathol 2010;34(12):1812-1819
3. Bateman AC, Deheragoda MG: IgG4-related systemic sclerosing disease-an emerging and under-diagnosed condition. Histopathology 2009;55(4):373-383
Method Name
Nephelometry
Specimen Type
SerumOrdering Guidance
This test only quantitates the IgG4 protein. If quantitation of all IgG subclass types is wanted, order IGGS / IgG Subclasses, Serum.
Specimen Required
Patient Preparation: Fasting preferred but not required
Container/Tube:
Preferred: Serum gel
Acceptable: Red top
Specimen Volume: 1 mL
Specimen Minimum Volume
0.5 mL
Specimen Stability Information
Specimen Type | Temperature | Time | Special Container |
---|---|---|---|
Serum | Refrigerated (preferred) | 14 days | |
Ambient | 14 days | ||
Frozen | 14 days |
Reference Values
0-<5 months: ≤19.8 mg/dL
5-<9 months: ≤20.8 mg/dL
9-<15 months: ≤22.0 mg/dL
15-<24 months: ≤23.0 mg/dL
2-<4 years: 0.4-49.1 mg/dL
4-<7 years: 0.8-81.9 mg/dL
7-<10 years: 1.0-108.7 mg/dL
10-<13 years: 1.0-121.9 mg/dL
13-<16 years: 0.7-121.7 mg/dL
16-<18 years: 0.3-111.0 mg/dL
≥18 years: 2.4-121.0 mg/dL
Test Classification
This test has been cleared, approved, or is exempt by the US Food and Drug Administration and is used per manufacturer's instructions. Performance characteristics were verified by Mayo Clinic in a manner consistent with CLIA requirements.CPT Code Information
82787
LOINC Code Information
Test ID | Test Order Name | Order LOINC Value |
---|---|---|
IGGS4 | Immunoglobulin Subclass IgG4, S | 2469-5 |
Result ID | Test Result Name | Result LOINC Value |
---|---|---|
IGGS4 | Immunoglobulin Subclass IgG4, S | 2469-5 |
mml-Neuroimmunology, mml-CNS-Infections