Uremic bleeding frequently occurs in dialysis patients. Although its mechanism is not well characterized, acquired platelet dysfunction has been implicated in its pathogenesis. Skin bleeding time has been used to characterize platelet dysfunction in this population. However, the bleeding time is prone to error. The goal of this study was to compare the bleeding time to the novel platelet function parameters platelet contractile force and clot elastic modulus as well as platelet aggregation studies in controls and patients receiving maintenance hemodialysis.
Forty-five subjects completed this study (25 controls, 20 dialysis). All subjects had the Ivy skin bleeding time procedure performed, as well as the collection of whole blood samples for the determination of platelet contractile force, clot elastic modulus, % von Willebrand Factor antigen, and platelet aggregation studies. Pearson's correlation determined the relationships between skin bleeding time and platelet function and clot structure parameters and markers of renal dysfunction.
Bleeding time was significantly prolonged in the dialysis group relative to controls. The platelet function parameters were not significantly different between groups. There was a significant relationship between bleeding time and creatinine concentration, however, no relationship existed between bleeding time and platelet function parameters.
Skin bleeding time poorly correlates with measurements of platelet function. There were no significant differences noted in platelet function between the groups despite the prolongations in bleeding time in the dialysis group. These data may suggest that the bleeding time reflects perturbations in platelet adhesion or secretion, and not aggregation. Further study is needed to characterize platelet function in dialysis patients.
"Some authors have theorized that uremic toxins only cause defective aggregation in the high shear forces of the vascular flow system and not within the artificial environment of the aggregometer . Others have suggested that bleeding tendencies may not relate to aggregation at all but more so to platelet adhesion and/or secretion . Defects in cyclooxygenase can be investigated by addition of this enzyme's substrate, AA. "
[Show abstract][Hide abstract] ABSTRACT: Background:
Platelet function analysis utilizing platelet-rich plasma and optical density based aggregometry fails to identify patients at risk for uremia associated complications.
We employed whole blood platelet aggregation analysis based on impedance as well as determination of ATP release from platelet granules detected by a chemiluminescence method. Ten chronic kidney disease (CKD) stage 4 or 5 predialysis patients underwent platelet evaluation. Our study aims to evaluate this platform in this patient population to determine if abnormalities could be detected.
Analysis revealed normal aggregation and ATP release to collagen, ADP, and high-dose ristocetin. ATP release had a low response to arachidonic acid (0.37 ± 0.26 nmoles, reference range: 0.6-1.4 nmoles). Platelet aggregation to low-dose ristocetin revealed an exaggerated response (20.9 ± 18.7 ohms, reference range: 0-5 ohms).
Whole blood platelet analysis detected platelet dysfunction which may be associated with bleeding and thrombotic risks in uremia. Diminished ATP release to arachidonic acid (an aspirin-like defect) in uremic patients may result in platelet associated bleeding. An increased aggregation response to low-dose ristocetin (a type IIb von Willebrand disease-like defect) is associated with thrombus formation. This platelet hyperreactivity may be associated with a thrombotic diathesis as seen in some uremic patients.
[Show abstract][Hide abstract] ABSTRACT: Liver biopsy is useful for staging fibrosis in chronic hepatitis C (CHC) patients with end-stage renal disease (ESRD) to determine renal transplant eligibility and to make CHC treatment decisions. There is concern about an increased risk associated with percutaneous liver biopsy (PCNB) in ESRD patients. We compared the safety of PCNB in CHC patients with and without ESRD.
We reviewed PCNBs performed between 1996 and 2004 for technique, histology, and complications in 78 ESRD patients with CHC and in 241 control patients with CHC and no renal failure, randomly matched for age, sex, and race. Platelet counts, prothrombin, and partial thromboplastin times, but not bleeding times, were checked before biopsy. Deamino-8-D-arginine vasopressin was not given before the biopsy.
The mean age of the patients was 50 years; 72% were male, 97% were African American, and 3% were Caucasian. The control group had a significantly higher proportion of patients with advanced fibrosis (P < .04). Only 1 patient with ESRD (1.3%) developed a moderate complication. Five controls (2.1%) developed complications, 3 of which were severe.
Severe complications after PCNB are uncommon, and patients with ESRD and CHC are at no increased risk. Testing for bleeding time and the routine use of deamino-8-D-arginine vasopressin are not necessary before PCNB in patients with ESRD.
Clinical gastroenterology and hepatology: the official clinical practice journal of the American Gastroenterological Association 12/2007; 5(11):1316-20. DOI:10.1016/j.cgh.2007.07.010 · 7.90 Impact Factor
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