Test Details
Methodology
Immunologic
Result Turnaround Time
3 - 5 days
Turnaround time is defined as the usual number of days from the date of pickup of a specimen for testing to when the result is released to the ordering provider. In some cases, additional time should be allowed for additional confirmatory or additional reflex tests. Testing schedules may vary.
Use
Evaluate sinopulmonary infections, asthma; immunotherapy hyposensitization; evaluate allergies
Special Instructions
State patient's age on the request form.
Limitations
This procedure is not suitable for the measurement of samples containing rheumatoid factor, paraproteins, other circulating immune complexes (CICs), or for lipemic or hemolyzed samples due to the unpredictable degree of nonspecific light scatter these sample types may generate. The results obtained from measuring IgG subclasses should not be used in assessing atopy in allergic patients.
Custom Additional Information
Measurement of serum IgG4 can aid in the diagnosis of IgG4-RD. According to two recent meta-analyses, the pooled sensitivity and specificity of a serum IgG4 ≥135 mg/dL is 85-87.2% and 82.6-93%, respectively.1,2 Although elevated serum IgG4 is consistent with the diagnosis of IgG4-RD, not all patients will have elevated concentrations.
IgG4 related disease (IgG4-RD) encompasses a constellation of individual organ disorders that share particular pathologic, serologic, and clinical features. These disorders were previously thought to be unrelated. They are characterized by the infiltration of IgG4+ plasma cells and an elevated serum IgG4.1
Common features of IgG4-RD include:3
• Elevated serum IgG4 (≥135 mg/dL)
• Clinical examination identifying swelling or masses in single or multiple organs
• Histopathological evidence of infiltrating IgG4+ plasma cells and fibrosis
• Imaging identifying narrowing of ducts and/or enlargement of organs
IgG4-RD includes disorders such as:3
• Type 1 (IgG4-related) autoimmune pancreatitis (AIP)
• Salivary gland disease (Mikulicz's disease)
• Nypophysitis
• Riedel thyroiditis
• Interstitial pneumonitis
• Nephritis
• Prostatitis
• Lymphadenopathy
• Retroperitoneal fibrosis
• Inflammatory aortic aneurysm
Specimen Requirements
Specimen
Serum
Volume
1 mL
Minimum Volume
0.4 mL
Container
Red-top tube or gel-barrier tube
Collection Instructions
Transfer specimen to a plastic transport tube.
Stability Requirements
Temperature | Period |
|---|---|
Room temperature | 3 days |
Refrigerated | 14 days |
Frozen | 14 days |
Freeze/thaw cycles | Stable x3 |
Reference Range
See table.
Age | Range (mg/dL) |
|---|---|
Cord | 1−47 |
0 to 2 m | 1−33 |
3 to 5 m | 1−14 |
6 to 8 m | 1−30 |
9 to 35 m | 1−65 |
3 to 4 y | 1−71 |
5 to 6 y | 2−96 |
7 to 8 y | 3−98 |
9 to10 y | 4−110 |
11 to 12 y | 4−114 |
13 to 14 y | 4−107 |
15 to 17 y | 3-119 |
18 to 19 y | 3−104 |
>19 y | 2−96 |
Storage Instructions
Refrigerate
Causes for Rejection
Gross lipemia; hemolysis
Footnotes
LOINC® Map
| Order Code | Order Code Name | Order Loinc | Result Code | Result Code Name | UofM | Result LOINC |
|---|---|---|---|---|---|---|
| 160531 | IgG, Subclass 4 | 2469-5 | 160531 | IgG, Subclass 4 | mg/dL | 2469-5 |
| Order Code | 160531 | |||||
| Order Code Name | IgG, Subclass 4 | |||||
| Order Loinc | 2469-5 | |||||
| Result Code | 160531 | |||||
| Result Code Name | IgG, Subclass 4 | |||||
| UofM | mg/dL | |||||
| Result LOINC | 2469-5 |