Low plasma levels of antithrombin III due to excessive urinary loss are thought to
be the cause of thrombotic complications in patients with the nephrotic syndrome.
To see whether protein C (PC), another antithrombotic protein, is also reduced in
plasma by the same mechanism, plasma and urinary protein C were determined in 24 patients
with nephrotic syndrome and no thrombotic complication, and compared to plasma and
urinary antithrombin III. Twenty patients (83%) had high plasma levels of protein
C activity (mean ± SD 157 ± 41 U/dl) and antigen (158 ± 41). Even though measurable
amounts of PC antigen were found in the urines of all but two patients the urinary
loss of protein C relative to its plasma concentration was about 40 times lower than
that of antithrombin III. High protein C might help to counteract hypercoagulability
in nephrotic syndrome.
Key words
Protein C - Antithrombin III - Nephrotic syndrome