What does the Beta-2-Glycoprotein I Antibody, IgG test measure?

Why is Beta-2-Glycoprotein I Antibody, IgG measured?

β2GPI IgG is one of the three core laboratory criteria for antiphospholipid syndrome, alongside lupus anticoagulant and anticardiolipin antibodies. Its presence correlates with thrombotic risk, particularly when titres are high and when accompanied by lupus anticoagulant. Isolated low-titre antibodies are less predictive and often require confirmatory testing 12 weeks later.

Reference ranges

Standard reference

<20 U/mL negative; 20–80 U/mL indeterminate; >80 U/mL positive (assay-dependent).

Functional medicine optimal

Negative (<20 U/mL) is optimal; persistent medium-to-high titres (>40 U/mL) correlate with thrombotic risk.

Units

U/mL, GPL U/mL

Reference ranges vary by laboratory and assay platform. Interpret in context of the issuing laboratory's stated range.