George et al proposed criteria for the diagnosis of drug-induced thrombocytopenia. This can be helpful when evaluating a patient with thrombocytopenia and several mechanisms are possible. The authors are from the University of Oklahoma.
|
Criterion |
Features |
|
1 |
both of the following: (a) the patient was treated with the drug before the onset of thrombocytopenia (drop in platelet count), AND (b) discontinuation of the drug resulted in a complete and sustained reversal of the thrombocytopenia (return to pretreatment platelet count) |
|
2 |
one of the following: (a) no other drugs were being taken at the time (b) other drugs were being taken AND these were EITHER continued OR reintroduced without apparent effect on the platelet count |
|
3 |
other causes of thrombocytopenia have been rules out |
|
4 |
re-exposure to the drug results in recurrence of the thrombocytopenia |
where:
• A patient may be thrombocytopenic before the onset of drug-induced thrombocytopenia. Discontinuation of causative drug should result to a return to the pretreatment platelet count.
• A person who has a high platelet count prior to drug therapy may experience a drop into the normal range. Therefore a person need not be thrombocytopenic to have a drug-induced drop in platelet count. It is just more obvious.
• Reversal of the thrombocytopenia may take some time, depending on the mechanism.
|
Criterion 1 |
Criterion 2 |
Criterion 3 |
Criterion 4 |
Diagnosis |
|
present |
present |
present |
present |
definite |
|
present |
present |
present |
not attempted |
probable |
|
present |
NA |
NA |
NA |
possible |
|
absent |
NA |
NA |
NA |
unlikely |
where:
• If the first 3 criteria are present but the 4th criteria is negative, then the diagnosis should be "possible".
• Other combinations of the criteria may be meaningful. For example, what if all of the other causes of thrombocytopenia have not been completely ruled out?
Specialty: Hematology Oncology, Clinical Laboratory, Clinical Pharmacology
