Thrombocytopenia

1. Due to immune destruction (ie, idiopathic thrombocy-topenic purpura [ITP]). Can be treated with IV immune globulin at a dose of 1 g/kg/day for up to three doses or Rho(D) immune globulin, 50 mcg/kg as a single dose. Alternative therapy for ITP includes prednisone, 2 mg/kg/day, or high-dose methylprednisolone, 30 mg/kg/day for up to 3 days. Patients should avoid use of NSAIDs and aspirin products.

2. From drug reaction. Discontinue drug and transfuse platelets as necessary.

D. vWD. Treatment of patients with type 1 vWD (the most common form) is as follows.

1. Minimal bleeding or minor surgical procedures. Give desmopressin acetate (DDAVP), which promotes release of vWF from endothelial cells.

a. Intranasal dose. Administer 150 mcg for patients < 50 kg and 300 mcg for patients > 50 kg (use 1.5 mg/mL concentration).

b. IV dose. Administer 0.3 mcg/kg. 2. Major surgery or significant bleeding. Administer a factor

VIII concentrate containing high levels of vWF (ie, Humate P); vWF 1 unit/kg will raise plasma level 2 units/dL. Hemophilia. Recombinant factor products are the preferred treatment for deficiencies of factors VIII and IX. Treatment depends on severity of disease, presence of an inhibitor, and medical circumstances.

1. Factor VIII. Dose of factor VIII = unit/dL(%) desired rise in plasma factor VIII x body weight (kg) x 0.5; T1/2 of factor VIII is 12 hours.

2. Factor IX. A 1 unit/kg dose of factor IX results in 1 unit/dL rise in plasma factor IX level; T1/2 of factor IX is 18-24 hours.

DIC. Treat the underlying disease and support patient with appropriate blood products, including RBCs, platelets, plasma, and cry-oprecipitate. Dose guidelines are packed RBCs, 10-15 mL/kg; fresh frozen plasma, 10-20 mL/kg; and cryoprecipitate, 1 bag (unit)/5 kg up to 10 bags.

Vitamin K deficiency. SQ route is preferred due to hypersensitivity to IV and IM injections. Dose is 1-2 mg SQ as a single dose. Oral dose is 2.5-5 mg daily.

VI. Problem Case Diagnosis. The 14-month-old boy was diagnosed with moderate factor VIII deficiency (factor VIII level of 1-5%). The APTT was also noted to be prolonged. Patient improved with factor VIII replacement and IV fluids.

VII. Teaching Pearl: Question. A patient with severe hemophilia A is treated for bleeding with 25 units/kg recombinant factor VIII concentrate. What is the expected postinfusion factor VIII level?

VIII. Teaching Pearl: Answer. The expected factor VIII level is 50%. REFERENCES

Lusher JM. Clinical and laboratory approach to the patient with bleeding. In: Nathan DG, Orkin SH, Look T, Ginsburg D, eds. Hematology of Infancy and Childhood. Saunders, 2003:1515-1526. Montgomery RR, Gill JC, Scott JP. Hemophilia and von Willebrand disease. In: Nathan DG, Orkin SH, Look T, Ginsburg D, eds. Hematology of Infancy and Childhood. Saunders, 2003:1547-1576. Pruth RK, Bleeding disorders: An overview and clinical practice. In: Tefferi A, ed. Primary Hematology. Humana Press, 2001:303-316.

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