Summary
Factor XII clotting activities and antigen levels were assayed in 14 plasma samples
from 10 patients with nephrotic syndrome; the group was heterogeneous clinically and
histologically. Factor XII was low at initial sampling in 7 of the 10 patients; in
7 of the 14 samples, factor XII antigen was in excess over clotting activity. Inhibition
of factor XII could not be demonstrated; excess plasma antigen and urinary antigen
(when present) had normal patterns on crossed-immunoelectrophoresis, indicating no
major changes in charge or size. In 3 patients tested more than once, plasma levels
of factor XII were increased up to 6fold in steroid-induced remission.
Of other hemostatic factors assessed for comparison, factor VIII was elevated in 11
of the 14 samples; eight of these had elevated factor VII levels as well. Eight samples
from six patients showed low antithrombin III levels; one of these patients had recurrent
thromboses. Antithrombin III levels correlated with the serum albumin concentration.
Only two of the eight urines tested had detectable factor XII antigen; a third had
factor IX and prothrombin and no factor XII. Plasminogen and antithrombin III were
readily demonstrated in all urine samples with higher concentrations in those patients
with less selective proteinuria. Urinary and plasma levels were not correlated, suggesting
that increased consumption or turnover was not simply related to increased filtration.
Keywords
Nephrotic syndrome - Hemostasis - Factor XII
