Immunoglobulin G, Subclass 4

TEST: 160531
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CPT: 82787
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Synonyms

  • IgG Subclass 4
  • IgG4

Special Instructions

State patient's age on the request form.

Expected 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.

Related Information

Related Documents

Specimen Requirements

Specimen

Serum

Volume

1 mL

Minimum Volume

0.4 mL

Container

Red-top tube or gel-barrier tube

Collection

Transfer specimen to a plastic transport tube.

Storage Instructions

Refrigerate

Stability Requirements

Temperature

Period

Room temperature

3 days

Refrigerated

14 days

Frozen

14 days

Freeze/thaw cycles

Stable x3

Causes for Rejection

Gross lipemia; hemolysis

Test Details

Use

Evaluate sinopulmonary infections, asthma; immunotherapy hyposensitization; evaluate allergies

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.

Methodology

Immunologic

Reference Interval

See table.

Immunoglobulin G, Subclass 4

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

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

Footnotes

1. Xu WL, Ling YC, Wang ZK, Deng F. Diagnostic performance of serum igg4 level for igg4-related disease: a meta-analysis. Sci. Rep. 2016 Aug 25;6:32035.27558881
2. Hao M, Liu M, Fan G, Yang X, Li J. Diagnostic value of serum igg4 for igg4-related disease: A prisma-compliant systematic review and meta-analysis. Medicine (Baltimore). 2016 May;95(21):e3785.27227950
3. Umehara H, Okazaki K, Masaki Y, et al. Comprehenisve diagnostic criteria for igg4-related disease (igg4-rd), 2011. Mod Rheumatol. 2012 Feb;22(1):21-30.22218969

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

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