Idiopathic thrombocytopenic purpura (ITP) is a well-recognized
bleeding disorder in
children. The incidence is difficult to estimate, but symptomatic cases may occur at a rate of 4-8 cases per 100,000 children per year. The greatest
frequency of occurrence is between 2 and 8 years of age. The
etiology for ITP remains unclear, but the
pathophysiology is believed to be related to an immune-mediated process. It is believed that when
antibodies are made to fight a particular
virus, these same antibodies attach to
platelets and the spleen and then destroys the platelets because they are recognized as foreign. Clinical symptoms at presentation include
petechiae,
bruising,
bleeding from mucous membranes, or
prolonged bleeding from abrasions. Symptomatic bleeding is not usually seen until the platelet count is less than 20,000/uL.
Fatal hemorrhages have been reported in less than 1% of all patients. Treatment for acute presentation is symptomatic and has included
prednisone,
intravenous immunoglobulin (IVIG), and
anti-D antibody. These are not curative therapies. Some experts suggest that no therapy is necessary for the asymptomatic patient, with no difference in the recovery of platelet counts over time. The natural history for recovery from ITP is that 65-85% of children will recover completely, with or without therapy, between 8 weeks and 6 months from diagnosis. Approximately 15-20% of patients will continue with persistently low platelet counts (150,000/uL) beyond 6 months and will be defined as having a chronic disease.
Anti-D antibody (WinRho) is a relatively new therapy for ITP. Infusion of anti-D antibody causes a
transient hemocytic anemia in the patient. Along with the clearance of antibody-coated RBCs, there is prolonged survival of platelets due to the blockade of the Fc receptors of the
reticuloendothelial cells. The platelet count does not increase until 48 hours after an infusion of anti-D antibody, therefore it is not an appropriate therapy for patients who are actively bleeding. The benefits of choosing anti-D antibody therapy over prednisone or IVIG is that anti-D can be given in one dose over 5-10 minutes and is significantly less expensive than IVIG. Historically, patients who are treated with prednisone must first undergo a
bone marrow examination to rule out
leukemia. Therefore, the use of anti-D alleviates the need for a bone marrow examination.
Patients eligible for anti-D therapy include: 1) Children>1 year and <19 years; 2) Rh (D) positive blood type; 3) normal WBC and
hemoglobin for age; platelets<30,000/uL; 4) no active mucosal bleeding; 5) no prior history of reaction to plasma products; 6) no patient known to be IgA deficient; 7) no concurrent infection; 8) no patient with Evan syndrome; 9) no patient with suspected lupus or other collagen/vascular disorder.
The proper administration of anti-D (WinRho) is 50 mcg/kg/day mixed in 25-30cc normal saline over 5-10 minutes. Premedicate the child with
Tylenol 10-15mg/kg p.o. 5-10 minutes before infusion.
The child should be observed for a minimum of one hour with IV in place, and baseline vital signs are obtained prior to infusion and again 5 minutes, 20 minutes, and 60 minutes after start of infusion.
Fever,
chills, and
headache may occur during or shortly after the infusion. A drop in hemoglobin and
hematocrit should be expected after anti-D infusion; however, if the hemoglobin drops more than 2g/dl, no further anti-D therapy is recommended. If fever, chills, or headache occur, Benadryl (1mg/kg IV with a maximum of 50mg) and Solucortef (2mg/kg IV) should be given and the child should be observed for an additional hour.
Nursing care includes teaching regarding possible side effects of anti-D therapy as well as teaching regarding limitation in activities while the child's platelet count is <50,000 to 100,000/uL. Children with ITP should not participate in ANY contact sports, bike riding, skate-boarding, roller-blading, climbing or running. Parents are encouraged to engage their children in quiet activities and to prevent any injuries to the child's head.
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