Diagnostic Use
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 4 IgG subclasses show considerable differences in their properties, including ability to fix complement, to bind to macrophages and to pass through the placenta.
IgG subclasses aid in the diagnosis of IgG4 related disease however in a proportion of patients with histologically confirmed IgG4 related disease the IgG4 in the serum may be normal. IgG subclasses have limited use in the assessment of antibody mediated immune function.
Patients with suspected immunodeficiency, severe or recurrent infections should be discussed with the clinical immunology team.
Reference Intervals
The normal adult reference interval has been verified by our testing platform.
| Age |
IgG1 g/L |
IgG2 g/L |
IgG3 g/L |
IgG4 g/L |
| Adult (>15 years) |
3.2 – 10.20 |
1.20 – 6.60 |
0.20 – 1.90 |
0.00 – 1.30 |
The normal paediatric serum reference interval stated below are based on those published in the Protein Reference Unit Handbook PRU Test Profile
These have not been verified on our testing platform but are intended for guidance purposes only.
Further paediatric reference interval data is provided in literature. PRU Test Profile and Allergy Testing Lab Online , Biochemistry, Bence Jones Protein Test UK , Autoimmune, Immunology
Expected values may vary with age, sex, sample type, diet and geographical location.
| Age |
IgG1 g/L |
IgG2 g/L |
IgG3 g/L |
IgG4 g/L |
| 0 – 6 Months |
1.50 – 3.00 |
0.30 – 0.50 |
0.10 – 0.60 |
<0.50 |
| 6 months – 2 years |
2.30 – 5.80 |
0.30 – 3.90 |
0.10 – 0.80 |
<0.50 |
| 2 years – 5 years |
2.30 – 6.40 |
0.70 – 4.50 |
0.10 – 1.10 |
<0.80 |
| 5 years – 10 years |
3.60 – 7.30 |
1.40 – 4.50 |
0.30 – 1.10 |
<1.00 |
| 10 years – 15 years |
3.80 – 7.70 |
1.30 – 4.60 |
0.20 – 1.20 |
<1.10 |
Limitations / Interference
Hemolysis (>400 index)
Lipaemia
Icterus
Uncertainty of Measurement
IgG1: 7%
IgG2: 8%
IgG3: 7%
IgG4: 8%