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Thrombocytopenia secondary to high valproate levels in children with epilepsy
M R Delgado1, A R Riela, J Mills
1Department of Neurology, University of Texas Southwestern Medical Center at Dallas.
Insights
Valproate medication can cause low platelet counts (thrombocytopenia) in children with epilepsy. Monitoring serum valproate levels and reducing the dose can help manage this side effect safely.
Area of Science:
- Neurology
- Pediatrics
- Pharmacology
Background:
- Epilepsy is a common neurological disorder in children.
- Valproate is a widely used antiepileptic drug.
- Thrombocytopenia is a potential side effect of valproate therapy.
Purpose of the Study:
- To determine the frequency of valproate-induced thrombocytopenia in pediatric epilepsy patients.
- To identify factors associated with valproate-induced thrombocytopenia.
- To guide management strategies for this adverse event.
Main Methods:
- Retrospective review of 306 children with epilepsy treated with valproate.
- Analysis of platelet counts and serum valproate levels.
- Correlation of thrombocytopenia with patient age, duration of valproate use, and concomitant antiepileptic medications.
Main Results:
- 21% (64/306) of children developed thrombocytopenia.
- Low platelet counts (<100 x 10(3)/mm3) occurred in 32 patients.
- Thrombocytopenia was strongly associated with serum valproate levels >140 micrograms/mL.
- Dose reduction typically normalized platelet counts.
- Duration of valproate use was correlated with thrombocytopenia.
Conclusions:
- High serum valproate levels are the most common cause of thrombocytopenia in children with epilepsy.
- Valproate-induced thrombocytopenia can often be managed by dose reduction rather than discontinuation.
- Close monitoring of platelet counts is recommended for patients with high serum valproate levels.
Abstract:
We reviewed the frequency of valproate-induced thrombocytopenia in children with epilepsy in our institution. Sixty-four (21%) of 306 children taking valproate developed thrombocytopenia. Thirty-two of these 64 patients had at least one platelet count lower than 100 x 10(3)/mm3. Eight patients developed signs of bleeding. Low platelet levels were typically noted in patients with serum valproate levels of over 140 micrograms/mL, and reduction of the medication dose usually resulted in a prompt increase in the number of platelets. Only one patient developed thrombocytopenia unrelated to high serum drug levels, and her platelet count did not improve until the drug was discontinued. Neither the age of the patient nor the use of additional antiepileptic medication correlated with the platelet count. However, duration of valproate use was related. These data suggest that, although valproate may cause thrombocytopenia via more than one mechanism, by far the most common factor is the presence of high valproate levels. Thus, the medication can be safely lowered in most patients with thrombocytopenia rather than discontinued altogether. Platelet counts should probably be monitored more carefully in patients known to have higher drug levels.