PC4d Image


Biomarker Associated with Thrombosis in SLE

Platelet-bound C4d (PC4d) is a patented blood test capable of uncovering significant association with thrombosis in patients with SLE, independent of antiphospholipid antibodies. Compared to those with low levels, elevation in PC4d is associated with history of thrombosis (OR 8.4 [95% CI 2.8-24.8]),1 and a 7.5 fold increase in all-cause mortality (HR 7.5).2 Persistent positive PC4d levels in SLE patients is significantly association with ischemic stroke (OR 5.5 [95% CI 1.7-17.6]).

Biomarker associated with specific adverse events in SLE

% of SLE Patients with Thrombosis

Data on File Exagen Inc. 2018


  1. Petri M, Conklin J, Apilado R, et al. Complement C4d Split Products in Combination with Lupus Anticoagulant and Low Complement Associate with Thrombosis in SLE [abstract]. Arthritis Rheumatol. 2018; 70
  2. Kao A, McBurney C, Sattar A, et al. Relation of platelet C4d with all-cause mortality and ischemic stroke in patients with systemic lupus erythematosus. Transl Stroke Res 2014; 5(4):510-518.