Lab Test

Immunoglobulin G (IgG) Subclasses

Immunoglobulin G Subclasses (1, 2, 3, 4) , Antrim #30941, EPIC: LAB6464, SOFT: IGSUB

Specimen Collection Criteria

Collect: One Gold-top SST tube. (Minimum Whole Blood: 4.0 mL)

Physician Office/Drawsite Specimen Preparation

Let specimen clot 30-60 minutes then immediately centrifuge to separate serum from cells. Do not refrigerate or freeze collection tube. Transfer serum to a plastic transport tube and refrigerate (2-8°C or 36-46°F) within 12 hours of collection. (Minimum serum: 0.5 mL)

Preparation for Courier Transport

Transport: Serum aliquot, refrigerated (2-8 °C or 36-46 °F). (Minimum serum: 0.5 mL)

Rejection Criteria

  • Plasma specimens.
  • Hemolyzed specimens.
  • Severely lipemic specimens.
  • This test is not suitable for the measurement of samples containing rheumatoid factor, paraproteins, or other circulating immune complexes.


0,Centrifuged SST tubes may be transported and stored at ambient temperatures (2o to 30o C; 36o to 86o F) for up to 48 hours. DO NOT FREEZE TUBES CONTAINING BLOOD. For longer storage, the serum should be removed from the gel and refrigerated (2o -8o C) or frozen at -20o C or below.

Red-top tubes and Microtainers® may be stored at ambient temperatures for up to 16 hours and for up to 3 days at refrigerator temperatures (2o - 8o C). DO NOT FREEZE TUBES CONTAINING BLOOD. For longer storage, the serum should be removed from the clot and refrigerated (2o -8o C) or frozen at -20o C or below.

0,Serum specimens (pour-overs) may be stored at room temperature (20o to 26o C; 68o to 79o F) for up to 1 week, refrigerator temperature (2o to 8o C; 36o to 47o F) for two weeks, and at -20o C (-4o F) for up to 3 months. Specimens stored at -70o C (-94o F) can be stored indefinitely.


Monday, Wednesday, Friday.
Results available in 1-3 business days.

Reference Range

Age Subclass 1
Subclass 2
Subclass 3
Subclass 4
0-4 months 56-215 0-82 7.6-82.3 0-19.8
5-8 months 102-369 0-89 11.9-74.0 0-20.8
9-14 months 160-562 24-98 17.3-63.7 0-22.0
15-23 months 209-724 35-105 21.9-55.0 0-23.0
2-3 years 158-721 39-176 17.0-84.7 0.4-49.1
4-6 years 209-902 44-316 10.8-94.9 0.8-81.9
7-9 years 253-1019 54-435 8.5-102.6 1.0-108.7
10-12 years 280-1030 66-502 11.5-105.3 1.0-121.9
13-15 years 289-934 82-516 20.0-103.2 0.7-121.7
16-17 years 283-772 98-486 31.3-97.6 0.3-111.0
greater than equal to 18 years 341-894 171-632 18.4-106.0 2.4-121.0

Test Methodology



Increased IgG1 levels are seen in patients with multiple sclerosis.

Increased IgG2 and IgG3 levels are seen in cystic fibrosis patients with chronic Pseudomonas aeruginosa infections.

Increased IgG4 levels are associated with patients with atopic dermatitis, food allergies, chronic exposure to environmental antigens (e.g., bee-keepers, pigeon breeder's), asthma, cystic fibrosis, some parasitic diseases, and in allergic individuals under hyposensitization regimens.

Decreased IgG1 levels are associated with end-stage renal failure, nephotic syndrome, and common variable immunodeficiency.

Decreased IgG2 levels are associated with bronchial asthma in children, idiopathic thrombocytopenia purpura, HIV, IgA deficiency, otitis media, recurrent sinopulmonary infections, bronchiectasis, alcoholic liver disease, ataxia teleangiectasia, bowel surgery and nephrotic syndrome.

Decreased IgG3 levels are associated with bronchial asthma in children, systemic lupus erythematosus, and recurrent sinopulmonary infections.

Decreased IgG4 levels are associated with idiopathic thrombocytopenia purpura, systemic lupus erythematosus, HIV, IgA and IgM deficiency, Wiskott-Aldrich's disease, alcoholic liver disease, ataxia teleangiectasia, and recurrent sinopulmonary infections.

Clinical Utility

Quantitation of the IgG subclasses helps to determine the immune status of patients with normal total IgG levels. Patients with a normal serum level of total IgG may have a clinically important deficiency of one or more IgG subclasses. Deficiencies in one or more IgG subclasses are associated with sinusitis, recurrent otitis media, asthma, respiratory tract infections, and impaired lung function with or without IgA deficiency.

Clinical Disease

IgG subclass deficiency occurs when there is an imbalance of the IgG subclasses with one or more subclasses being deficient. The etiology is unknown. These patients may be healthy but most have a history of frequent ear and sinus infections, bronchiectasis, and pneumonia. These infections are often caused by encapsulated bacteria such as Haemophilus influenzae, and Streptococcus pneumoniae, especially in the case of IgG2 deficiency.

CPT Code

82787x4, 82784.

Test Codes

Antrim #30941, EPIC: LAB6464, SOFT: IGSUB

Last Updated


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This directory currently reflects information only for specimens collected and/or processed at the
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