Inhibitor of the thrombin time in systemic amyloidosis: a common
coagulation abnormality
DA Gastineau, MA Gertz, TM Daniels, RA Kyle and EJ Bowie
Division of Hematology and Internal Medicine, Mayo Clinic, Rochester, MN
55905.
Patients with primary systemic amyloidosis (AL) often experience bleeding,
and we report a newly recognized coagulation abnormality in AL. Of 103
patients with primary systemic AL studied over 2 years, 41 had prolongation
of the thrombin time (range, 25 to 46 seconds; normal, less than 22
seconds) and reptilase time (range, 17 to 39 seconds; normal, 14 to 16
seconds). The fibrinogen from the plasma of 36 patients was precipitated by
beta-alanine and diluted to a concentration of approximately 200 mg/dL. The
thrombin times of the precipitated fibrinogens were normal in 34 patients,
implying that an inhibitor was responsible for the abnormal tests. The
addition of patient fibrinogen-free plasma to normal plasma prolonged the
thrombin times, and this result confirmed the presence of an inhibitor. The
inhibitor is more likely to be present in patients with nephrotic syndrome
(20 of our patients) and congestive heart failure (six). A circulating
monoclonal protein (24 patients), the presence of amyloid liver involvement
(eight), and the presence of amyloid neuropathy (nine) were not
predisposing factors. Only one patient had deficiency of factor X. We
conclude that inhibition of fibrinogen conversion to a fibrin clot rather
than dysfibrinogenemia is the cause of the prolonged thrombin time in
primary systemic AL.
Volume 77,
Issue 12,
pp. 2637-2640,
06/15/1991
Copyright © 1991 by The American Society of Hematology
