The effect of uremia on platelet contractile force, clot elastic modulus and bleeding time in hemodialysis patients
ABSTRACT 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.
- SourceAvailable from: Jonas A Sjøland
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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 · 6.53 Impact Factor
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ABSTRACT: At least five groups have evaluated treatment for patients with decompensated cirrhosis preliminary to liver transplantation.330–334 In the earliest reported study, 32 patients awaiting liver transplantation were considered for antiviral treatment, but over one-half were found ineligible because of cytopenias.330 Among those treated with standard or low doses of interferon alfa-2b or low doses of both interferon alfa-2b and ribavirin, 33% became HCV RNA negative. Almost all developed adverse effects, most of which was graded as severe. In a second study, 30 patients with HCV-related cirrhosis destined for liver transplantation (half graded as CTP class A) were treated with interferon alfa-2b, 3 mU daily and ribavirin, 800 mg/day if their presumed time to liver transplantion was less than 4 months.331 After a median treatment duration of 12 weeks, 30% responded to treatment and then underwent liver transplantation, 2/3 of whom remained HCV RNA negative over a median follow-up period of 46 weeks. Sixty percent developed neutropenia. Reported in the same year was a study of 20 patients, most with genotype 1 infection, who were treated before transplantation for a mean of 14 months with interferon alfa-2b in a dose of 5 mU daily.332 At transplantation, 60% were HCV RNA negative, but only 20% remained negative after transplantation. A fourth study involved 124 patients with advanced cirrhosis (CTP classes A, B and C) treated mainly with interferon alfa-2b plus ribavirin, and less frequently, with pegylated interferon plus ribavirin.333 Treatment began with half doses that were increased incrementally as tolerated at 2 week intervals (referred to as a low accelerating dose regimen), and growth factors were used as needed. An SVR developed in 13% of patients with genotype 1 and in 50% with non-genotype 1 infections. Adverse events were frequent, requiring dose reductions or treatment termination, but among those who did become HCV RNA negative before transplantation, 80% remained negative 6 or more months after transplantation. The most recent study is the only one to include non-treated controls but these consisted of patients unwilling to participate in the study.334 The treatment administered was peginterferon alfa-2b, 1.0 μg/kg body weight given weekly and ribavirin, 800 to 1000 mg daily for 24 weeks. An SVR developed in 44% of the patients with HCV genotypes 2 or 3, and in 7% of those with genotypes 1 or 4. Treatment had to be discontinued in 20%, was reduced in 39%, and was tolerated in 41%. Over a 30-month follow-up period, decompensated events occurred in 83% of the controls, 62% of the non-responders, and in 23% of the patients who had developed an SVR. The conclusion of this study was that antiviral therapy can be life-saving, improves hepatic function, and that treatment seems appropriate for persons with genotype 2 and 3 infections particularly in those with cirrhosis, CTP classes A and B.Hepatology 04/2009; 49(4):1335-74. DOI:10.1002/hep.22759 · 11.19 Impact Factor