Monitoring parameter for Aspirin induced Thrombocytopenia

• Drug-induced thrombocytopenia is a reversible form of thrombocytopenia (ie, platelets <150,000/microL) that should be suspected in a patient who presents with new onset of thrombocytopenia or recurrent episodes of acute thrombocytopenia, without an obvious alternative etiology

• The thrombocytopenia is typically isolated (ie, unaccompanied by anemia, leukopenia, leukocytosis, or coagulation abnormalities) and severe (ie, platelet count <20,000/microL with clinical bleeding) in a patient taking one or several different medications or herbal remedies, foods, beverages, or other substances.

•  acetaminophen and naproxen, for which drug-dependent, platelet-reactive antibodies have only been identified for drug metabolites and not for the intact drug

The clinical course and outcome has been described in several publications:

• The median time for daily exposure to a drug before thrombocytopenia occurs is six days (range 1 to 10).

• Median recovery after discontinuation of the suspected drug occurred in five to seven days, similar to the median recovery rate of eight days reported from a Danish registry.

• Twenty-three of 266 patients (9 percent) with definite or probable evidence for drug-induced thrombocytopenia had major hemorrhage, including two patients (0.8 percent) who died of bleeding. This mortality rate from bleeding was lower than the value of 3.6 percent reported from a Danish registry

Recommendation: 

No recommendation for routine monitoring parameter as the recovery is fast. Suggest following up patient if platelet counts are decreasing trend upon treatment initiation (platelet turn around takes an estimated 8-10 days). If values falls further can consider stopping therapy and monitor for increase after 1 week. If platelet count increases, the drug can be suspected to be the culprit and avoided

references:
1. www.uptodate.com
2. http://www.clevelandclinicmeded.com