Bleeding time

The NSAIDs prolong bleeding time and increase the effects of anticoagulants, lithium, cyclosporine, and the hydantoins. These dru may decrease the effects of diuretics or antihypertensive drug >. Long-term use of the NSAIDs with acetaminophen may increase the risk of renal impairment. 

A number of laboratory tests are available to measure the phases of hemostasis described above. The tests include platelet count, bleeding time, activated partial thromboplastin time (aPTT or PTT), prothrombin time (PT), thrombin time (TT), concentration of fibrinogen, fibrin clot stabifity, and measurement of fibrin degradation products. The platelet count quantitates the number of platelets, and the bleeding time is an overall test of platelet function. aPTT is a measure of the intrinsic pathway and PT of the extrinsic pathway. PT is used to measure the effectiveness of oral anticoagulants such as warfarin, and aPTT is used to monitor heparin therapy. The reader is referred to a textbook of hematology for a discussion of these tests. 

Vitamin K is an essential factor in the production of coagulation proteins within the liver. Elevated clotting times from decreased protein synthesis are indistinguishable from those produced by low vitamin K levels caused by malnutrition or poor intestinal absorption. Vitamin K (phytonadione) 10 mg subcutaneously daily for 3 days can help to establish whether the prolonged bleeding time results from loss of synthetic function in the liver or vitamin K deficiency. 

Nonpharmacologic Therapy The incidence and severity of bleeding associated with uremia has decreased since dialysis has become the mainstay of treatment for ESRD. Dialysis initiation improves platelet function and reduces bleeding time.42 Improved care of the patient with ESRD, with anemia treatment and improvement in nutritional status, are also likely contributors to decreased uremic bleeding. 

Pharmacologic Therapy Treatments used to decrease bleeding time in patients with uremic bleeding include cryoprecipitate, which contains various components important in platelet aggregation and clotting, such as von Willebrand factor and fibrinogen. Cryoprecipitate decreases bleeding time within 1 hour in 50% of patients. However, cost and the risk of infection have limited the use of cryoprecipitate. 

Desmopressin (DDAVP) increases the release of factor VIII (von Willebrand factor) from endothelial tissue in the vessel wall. Bleeding time is promptly reduced, within 1 hour of administration, and is sustained for 4 to 8 hours.42 Doses used for uremic bleeding are 0.3 to 0.4 mcg/kg intravenously over 20 to 30 minutes, 0.3 mcg/kg subcutaneously, or 2 to 3 mcg/kg intranasally. Repeated doses can cause tachyphylaxis by... 

Coenzyme Q10 is an antioxidant essential for mitochondrial function. A dose of 1200 mg daily was associated with a slower decline in UPDRS scores than patients not receiving coenzyme Q10. Lower doses were no better than placebo, but the drug continues to be studied in doses up to 2400 mg daily. Many formulations contain vitamin E, and patients should not exceed recommended daily allowances of this vitamin, as bleeding times may be prolonged.42,43... 

Hematologic von Willebrand disease Idiopathic thrombocytopenic purpura Factor VII defect causing impaired platelet adhesion and increased bleeding time Decrease in circulating platelets—can be acute or chronic... 

XIII Umbilical cord, intracranial, and joint bleeding recurrent miscarriages, impaired wound healing Normal PT, aPTT, thrombin time, bleeding time Specific factor XIII assay... 

In a patient presenting with a bleeding or clotting disorder, an initial evaluation should include bleeding time, prothrombin time (PT), activated partial thromboplastin time (aPTT), thrombin time, and platelet count. 

Nondialytic therapies that may temporarily shorten increased bleeding time include cryoprecipitate, desmopressin (l-deamino-8-D-arginine vasopressin), and estrogens. 

A double-blind, placebo-controlled study in which a 4 mg dose of molsidomine was orally administered confirmed the anti-aggregatory effects of the drug when administered intravenously. Although the anti-platelet effects were maintained 1 h after molsidomine administration, bleeding time was unaffected [89]. 

On the other hand, it should be noted that with some pyridazine derivatives, haemostatic activity has been observed [273-275], Thus for instance, sulphon-ylpyridazinones of type (73, R = HO, NH2NH, Me2N(CH2)3NH) have been reported to shorten the bleeding time in mice to an extent comparable to carbazochrom sodium sulphonate [275]. 

Normal bleeding time Increased bleeding time... 

Hematology The elevated bleeding time characteristic of CRF decreases toward normal after correction of anemia in epoetin alfa-treated patients. Reduction of bleeding time also occurs after correction of anemia by transfusion. Allow sufficient time to determine a patient s responsiveness before adjusting the dose. An interval of 2 to 6 weeks may occur between the time of a dose adjustment and a significant change in hemoglobin. 

Lab test abnormalities Aspirin has been associated with elevated hepatic enzymes, blood urea nitrogen and serum creatinine, hyperkalemia, proteinuria, and prolonged bleeding time. Dipyridamole has been associated with elevated hepatic enzymes. 

Prolonged bleeding time is normalized within 2 hours after administration of 20 mg methylprednisolone IV. Platelet transfusions also may be used to reverse the effect of ticlopidine on bleeding. If possible, avoid platelet transfusions because they may accelerate thrombosis in patients with TTP on ticlopidine. 

Gi bieeding Ticlopidine prolongs template bleeding time. Use with caution in patients who have lesions with a propensity to bleed (such as ulcers). Use drugs that might induce such lesions with caution in patients on ticlopidine. 

Dose-dependent inhibition of platelet aggregation can be seen 2 hours after single oral doses of clopidogrel. Platelet aggregation and bleeding time gradually return to baseline values after treatment is discontinued, generally in about 5 days. Pharmacokinetics ... 

Heparin inhibits reactions that lead to clotting, but does not significantly alter the concentration of the normal clotting factors of blood. Although clotting time is prolonged by full therapeutic doses, in most cases it is not measurably affected by low doses of heparin. Bleeding time is usually unaffected. 

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