P1077
PERSISTENCE OF CIRCULATING RESIDUAL HEPARIN IN ESRD PATIENTS UNDERGOING MAINTENANCE HEMODIALYSIS Free

ESRD patients who receive routine maintenance hemodialysis are administered with unfractionated heparin to prevent thrombotic complications. The hemostatic dysregulation along with detectable levels of circulating heparin may cause them to be in a hypocoagulable state. The purpose of this study is to determine the circulating levels of heparin in ESRD patients and its characterization using heparinase digestion methods.

Blood plasma samples collected at routine pre-dialysis sessions from 95 ESRD patients undergoing maintenance hemodialysis were analyzed for the presence of residual heparin utilizing standard laboratory methods such as aPTT, Anti-Xa and Anti-IIa activities On a centrifugal analyzer (ACL-Elite: Instrumentation Laboratory, Bedford, MA). The levels of heparin were calculated in terms of units per ml relative to the USP reference standard. Heparinase digestion was used to confirm the presence of heparin.

Blood plasma samples collected at routine pre-dialysis sessions from 95 ESRD patients undergoing maintenance hemodialysis were analyzed for the presence of residual heparin utilizing standard laboratory methods such as aPTT, Anti-Xa and Anti-IIa activities On a centrifugal analyzer (ACL-Elite: Instrumentation Laboratory, Bedford, MA). The levels of heparin were calculated in terms of units per ml relative to the USP reference standard. Heparinase digestion was used to confirm the presence of heparin.

The presence of residual heparin was demonstrated by both clot- based and amidolytic assays in the plasma samples collected from ESRD patients prior to their next-dialysis session. Since these samples were obtained 3 days following the last dialysis session the presence of significant levels of heparin was surprising. Upon heparinase treatment of these samples, the aPTT and the anti-Xa and IIa tests were restored to near normal levels. Our studies confirm the presence of residual heparin in pre-dialysis plasma samples obtained from ESRD patients. The Anti-IIa activity was greater pre-heparinase and it was not decreased to the same extent as Anti-Xa after heparinase digestion. These results suggest that heparin found in ESRD patient’s plasma is of high molecular weight origin with delayed clearance.