IGG SUBCLASSES - (S)

Test Code: IGGS

Alternate Name(s): IgG (Immunoglobulin G) Subclasses, IgG1, IgG2, IgG3, IgG4 (Immunoglobulins G1, G2, G3, G4)

Second-order testing for evaluation of patients with clinical signs and symptoms of humoral immunodeficiency or combined immunodeficiency (cellular and humoral).
 
In normal adults, IgG constitutes approximately 75% of the total serum immunoglobulin. Within the IgG class, the usual order of concentration of the 4 subclasses is IgG1>IgG2>IgG3>IgG4, but the actual concentration of each may vary markedly between individuals. The four IgG subclasses show considerable differences in their properties, including ability to fix complement, to bind to macrophages and to pass through the placenta. Abnormal levels of one or more subclass may be associated with certain conditions, including anaphylaxis, autoimmune- and gut diseases as well as hypo- and hyper-gammaglobulinemia.  Reduced production of IgG2 in children may be associated with recurrent infections.
 
Values should be used in conjunction with other laboratory and clinical findings.
 

_SH Immunology Test Requisition (R250-10-21)

Age (yrs)	g/L
	IgG1	IgG2	IgG3	IgG4
0 - 2	1.67 – 9.00	0.55 – 3.59	0.34 – 0.85	0.010 – 0.336
3 – 4	3.13 – 9.41	0.72 – 2.87	0.25 – 1.17	0.007 – 0.645
5 – 9	3.63 – 12.76	0.27 – 3.98	0.17 – 1.69	0.004 – 1.676
10 – 14	3.16 – 10.76	0.86 – 5.09	0.14 – 2.01	0.007 – 1.027
15 – 18	3.25 – 8.94	1.56 – 6.25	0.34 – 2.46	0.018 – 1.702
Adult 19+	3.82 – 9.29	2.42 – 7.00	0.22 – 1.76	0.039 – 0.864

 
Pediatric reference values adopted from Garcia-Prat M, Vila-Pijoan G, Martos Gutierrez S, et al. Age-specific pediatric reference ranges for immunoglobulins and complement proteins on the Optilite™ automated turbidimetric analyzer. J Clin Lab Anal. 2018;32:e22420. https://doi.org/10.1002/jcla.22420.
 
Adult reference values adopted from:
Binding Site, Optilite IgG1 Kit, INS006.OPT ver 15th October 2014
Binding Site, Optilite IgG2 Kit, INS007.OPT ver 11th August 2015
Binding Site, Optilite IgG3 Kit, INS008.OPT ver 30th January 2019
Binding Site, Optilite IgG4 Kit, INS009.OPT ver 23rd July 2019

Method of Analysis: Turbidimetry – Binding Site Optilite

Within 1 Week

Testing includes total immunoglobulin G (IgG) as well as the 4 subclasses of IgG.
 

	Reportable Range
IgG1	0.15 – 144.00 g/L
IgG2	0.02 – 28.00 g/L
IgG3	0.01 – 8.80 g/L
IgG4	0.004 – 64.800 g/L

 
Undetected antigen excess is a rare event but cannot be excluded. If these results do not agree with other clinical or laboratory findings, or if the sample is from a patient that has previously demonstrated antigen excess, the result must be checked by retesting at a higher sample dilution. Results should always be interpreted in conjunction with other laboratory tests and clinical evidence; any anomalies should be discussed with the laboratory.