Thus far, there has been no demonstration of a systemic factor which reflects the inflammatory process in idiopathic uveitis. In evaluating 103 patients with uveitis and no other apparent illness, we found that many of these patients had significantly higher levels of heparin-precipitable fraction (HPF) in their plasma (141 ± 75 mg/100 cc) than normal individuals (50 ± 20 mg/100 cc) or patients with nonuveitis eye disease ( 55 ± 33 mg/100 cc). Most of these patients had normal erythrocyte sedimentation rates. Heparin-precipitable fraction is a cryoprecipitable fibrinogenheparin complex found in heparinized plasma, believed to be formed as a result of activation of the clotting mechanism. There was no correlation between HPF levels and the type of uveitis, degree of observed inflammatory activity, or method of treatment.
Balis MS, Epstein WV. Elevated Heparin-Precipitable Fraction (HPF) in Patients With Uveitis. Arch Ophthalmol. 1971;85(5):548-552. doi:10.1001/archopht.1971.00990050550005