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HelpTest Code IGGS4 IgG4, Immunoglobulin Subclasses, Serum
Reporting Name
IgG4, Ig SubclassesUseful For
Supporting the diagnosis of IgG4-related disease
Performing Laboratory
Mayo Clinic Laboratories in Rochester
Specimen Type
SerumOrdering Guidance
This test only quantitates the IgG4 protein. If quantitation of all IgG subclass types is desired, order IGGS / IgG Subclasses, Serum.
Specimen Required
Patient Preparation: Fasting preferred but not required
Collection Container/Tube:
Preferred: Serum gel
Acceptable: Red top
Submission Container/Tube: Plastic vial
Specimen Volume: 1 mL
Collection Instructions: Centrifuge and aliquot serum into a plastic vial.
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: ≤49.1 mg/dL
4-<7 years: ≤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: ≤121.7 mg/dL
16-<18 years: ≤111.0 mg/dL
≥18 years: 2.4-121.0 mg/dL
Day(s) Performed
Monday through Friday
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 | IgG4, Ig Subclasses | 2469-5 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| IGGS4 | IgG4, Ig Subclasses | 2469-5 |
Clinical Information
The most abundant immunoglobulin isotype in human serum is 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 systemic inflammatory disease of unknown etiology, most often occurring in middle-aged and older men. Several organ systems can be involved, and the disease encompasses many previous and newly described diseases such as 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. These entities may be characterized by tumor-like swelling of the involved organs with infiltration by numerous IgG4-positive plasma cells with accompanying fibrosis. In addition, elevated serum concentrations of IgG4 are found in at least 50% of patients diagnosed with IgG4-related disease.
The diagnosis of IgG4-related disease may require 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 measured.
Interpretation
Elevated concentration of IgG4 is consistent with, but not diagnostic of, IgG4-related disease.
Cautions
Elevations in serum IgG4 concentrations are not specific to IgG4-related disease; they are also found in disorders such as multicentric Castleman disease, allergic disorders, Churg-Strauss syndrome, sarcoidosis, and other conditions.
Report Available
1 to 2 daysReject Due To
| Gross hemolysis | Reject |
| Gross lipemia | Reject |
| Gross icterus | OK |
Method Name
Turbidimetry