.
| IgG | (g/L) |
|---|---|
| Newborn to <2 weeks | 3.0 - 13.7 |
| >=2 weeks to <6 weeks | 1.2 - 6.0 |
| >=6 weeks to <6 months | 1.2 - 7.0 |
| >=6 months to <12 months | 3.0 - 10.5 |
| >=1 year to <4 years | 3.0 - 11.2 |
| >=4 years to <10 years | 5.0 - 13.3 |
| >= 10 years to <19 years | 6.0 - 15.0 |
| >=19 years to <70 years | 7.0 - 16.0 |
| >=70 years | 6.0 - 15.0 |
.
| IgA | (g/L) |
|---|---|
| Newborn to <1 year | 0.09 - 0.39 |
| >=1 year to <3 years | 0.19 - 1.09 |
| >=3 years to <6 years | 0.29 - 1.69 |
| >=6 years to <14 years | 0.3 - 2.4 |
| >=14 years to <19 years | 0.4 - 3.1 |
| >=19 years to <70 years | 0.8 - 4.0 |
| >=70 years | 0.8 - 4.0 |
| IgM | (g/L) |
|---|---|
| Newborn to <2 weeks | <0.5 |
| >=2 weeks to <13 weeks | 0.1 - 0.7 |
| >=13 weeks to <1 year | 0.1 - 0.9 |
| >=1 year to <19 years | 0.4 - 1.8 |
| >=19 years to <70 years | 0.4 - 2.5 |
| >=70 years | 0.4 - 2.4 |
Uncertainty of Measurement:
IgG 4%,
IgA 6%,
IgM 6%
Test performed 7 days a week
Principle: Immunoturbidometric
Analyser: COBAS
Reduced IgG
Reduced IgG levels may be due to primary immunodeficiency (eg X-linked hypogammaglobulinaemia, common variable immunodeficiency, severe combined immunodeficiency) or secondary causes (e.g. multiple myeloma, medications including B cell depleting agents such as rituximab). The lower reference limit of IgG can be lower in adults age >70 years or current smokers however in these groups it is not expected to be lower than 5.8 g/L
| Adult, IgG < 1 g/L |
Patients with severe hypogammaglobulinemia are at risk of life threatening or severe infection. Please refer to immunology for further advice. |
|
Adult, IgG 1 g/L - 3 g/L |
If there is no known cause, please investigate for secondary causes and consider a clinical immunology referral if no cause is identified. |
|
Adult, IgG 3 g/L- 5 g/L |
If no cause is identified or there is recurrent, particularly sinopulmonary, infections or other features of an immunodeficiency consider referral to clinical immunology. |
|
Paediatrics <12 years, <95th percentile |
If IgG levels are reduced and there is no known cause, consider a paediatric immunology referral. |
Low / undetectable IgA
Selective IgA deficiency (i.e. normal IgG and IgM) is seen in approximately 1:400 people and can occur in otherwise well individuals. It may be associated conditions (e.g. coeliac disease, inflammatory bowel disease), and anaphylactic reactions to blood products (when IgA is absent) and rarely recurrent sinopulmonary infection.
Total IgA levels can remain undetectable in normal children up to the age of 7 months. IgA deficiency cannot be reliably diagnosed under the age of 5 years.
Elevated IgA, IgM or IgG
Elevated immunoglobulin isotype levels may be polyclonal (eg in infection, autoimmune or non-immune liver disease or autoimmune diseases like Sjogren's syndrome) or monoclonal.
Serum protein electrophoresis to exclude a monoclonal gammopathy should be considered, particularly in patients with evidence of immunoparesis to at least one other immunoglobulin isotype or where IgG > 25g/L, IgA >10 g/L or IgM >10 g/L.
Serial monitoring of immunoglobulin IgG, A or M should ideally be done through the same laboratory. Inter-platform differences of up to 40% (for results at or below lower reference limit), 25% (for results within reference limits) and 15% (for results above upper reference limit) can be observed between laboratories using different platforms or assays. In patients with paraproteinemia, even greater between-method differences may be seen.
References :
Khan SR, Chaker L, Ikram MA, Peeters RP, van Hagen PM, Dalm VASH. Determinants and Reference Ranges of Serum Immunoglobulins in Middle-Aged and Elderly Individuals: a Population-Based Study. J Clin Immunol. 2021 Nov;41(8):1902-1914. doi: 10.1007/s10875-021-01120-5. Epub 2021 Sep 10. PMID: 34505230; PMCID: PMC8604889.
The Immunopathology team can be reached via email: immunology@adhb.govt.nz or via Lablink (09) 307 4949 ext 22000:
- Professor Rohan Ameratunga (Immunopathologist)
- Dr Maia Brewerton (Immunopathologist)
- Dr Miriam Hurst (Immunopathologist)
The chemical pathology team can be reached via email: chemicalpathologist@adhb.govt.nz or via Lablink (09) 307 4949 ext 22000 or 09-3078995
Emails will receive priority attention from the on-call chemical pathologist. Include the patients NHI.
After-hours: contact Lablink (Auckland City Hospital ext. 22000 or 09-3078995) or hospital operator for on duty staff after hours .
- Dr Samarina Musaad (Clinical Lead) : SamarinaM@adhb.govt.nz ext. 22402
- Dr Cam Kyle : CampbellK@adhb.govt.nz ext 22052
- Dr Weldon Chiu : WeldonC@adhb.govt.nz ext. 23427
- Dr Campbell Heron : CHeron@adhb.govt.nz ext. 23427
- Dr Sakunthala Jayasinghe Saku.Jayasinghe@adhb.govt.nz
- Dr Owen Yi WenyiYi@adhb.govt.nz