Correspondence
Vancomycin-Induced Immune Thrombocytopenia
N Engl J Med 2007; 356:2537-2538June 14, 2007
- Article
To the Editor:
In the report by Von Drygalski and colleagues on vancomycin-induced immune thrombocytopenia (March 1 issue),1 the positive human platelet factor 4 enzyme-linked immunosorbent assay (PF4 ELISA) was used to rule out the diagnosis of heparin-induced thrombocytopenia. Although this test is highly sensitive, it has been recommended2 that the test not be used alone but be combined with a functional assay, such as a 14C-serotonin release assay, which is the gold standard. Furthermore, the authors report that platelet counts increased after the withdrawal of vancomycin. However, in the patient with vancomycin-induced thrombocytopenia whose platelet counts are shown in Figure 1 of the article, intravenous immune globulin was administered, and her platelet count rose 3 days later. The timing of the administration of immune globulin was too close to the withdrawal of vancomycin to conclude that vancomycin was the only cause of the thrombocytopenia.
2 ReferencesMandip Panesar, M.D.
University at Buffalo, Buffalo, NY 14215
mpanesarmd@gmail.com 1
Von Drygalski A ,Curtis BR ,Bougie DW , et al. Vancomycin-induced immune thrombocytopenia. N Engl J Med 2007;356:904-910
Full Text | Web of Science | Medline2
Arepally G ,Reynolds C ,Tomaski A , et al. Comparison of PF4/heparin ELISA assay with the 14C-serotonin release assay in the diagnosis of heparin-induced thrombocytopenia. Am J Clin Pathol 1995;104:648-654
Web of Science | Medline
To the Editor:
Von Drygalski et al. report convincing data demonstrating that vancomycin-dependent antiplatelet antibodies cause vancomycin-induced immune thrombocytopenia. The authors observed that in most patients platelet levels returned to baseline after vancomycin was discontinued. However, they do not present data showing how long vancomycin-dependent antiplatelet antibodies remained in serum after vancomycin was discontinued. Is the persistence of vancomycin necessary for the maintenance of these antibodies?
Hiroshi Okamoto, M.D., Ph.D.
Tokyo Women's Medical University, Tokyo 1620054, Japan
hokamoto@ior.twmu. ac. jp To the Editor:
Von Drygalski et al. report that vancomycin-induced immune thrombocytopenia caused severe bleeding in 34% of patients (10 of the 29 for whom clinical follow-up information was obtained). Did the authors observe an increased incidence of venous thromboembolic or ischemic events in the patients?
Harris V.K. Naina, M.B., B.S.
Samar Harris, M.B., B.S.
Mayo Clinic, Rochester, MN 55905
naina.harris@mayo. edu Sarat Kuppachi, M.B., B.S.
Our Lady of Mercy Medical Center, Bronx, NY 10470Author/Editor Response
In response to Panesar, although a positive result on PF4 ELISA is not specific for the clinical diagnosis of heparin-induced thrombocytopenia, it is very sensitive and specific for the detection of antibodies associated with this condition.1 The diagnosis of heparin-induced thrombocytopenia is almost untenable in patients with a negative or a very weak positive result on PF4 ELISA.1 Therefore, it is very unlikely that heparin-induced thrombocytopenia was present in any of the 29 patients with vancomycin-dependent antibodies and thrombocytopenia described in our report. The patient whose clinical course is shown in Figure 1 of our article had an initial rise in the platelet count 3 days after a second intravenous infusion of immune globulin but did not have a count of 100,000 per cubic millimeter until day 6. It is certainly possible that intravenous immune globulin shortened the duration of thrombocytopenia in this patient. However, an equally rapid platelet response after the discontinuation of vancomycin occurred in 12 other patients who did not receive intravenous immune globulin.
In response to Okamoto's question, we note that clinically significant vancomycin-dependent antibodies almost certainly persisted for at least 6 months in two patients who had a recurrence of severe thrombocytopenia when reexposed to vancomycin at a later time. We did not perform sequential studies to determine how long antibodies remained detectable in the other patients.
In response to Naina and colleagues, none of the patients described in our report had thrombosis in conjunction with vancomycin-induced thrombocytopenia. To our knowledge, an association between immune thrombocytopenia and thrombosis has been described only in patients with sensitivity to heparin1,2 and platelet-function inhibitors of the fiban class.3
3 ReferencesAnnette Von Drygalski, M.D.
Medical College of Wisconsin, Milwaukee, WI 53226Daniel Bougie, Ph.D.
Richard H. Aster, M.D.
BloodCenter of Wisconsin, Milwaukee, WI 53201-2178
richard.aster@bcw. edu 1
Davoren A ,Aster RH . Heparin-induced thrombocytopenia and thrombosis. Am J Hematol 2006;81:36-44
CrossRef | Web of Science | Medline2
Warkentin TE . Think of HIT when thrombosis follows heparin. Chest 2006;130:631-632
CrossRef | Web of Science | Medline3
Scirica BM ,Cannon CP ,Cooper R , et al. Drug-induced thrombocytopenia and thrombosis: evidence from patients receiving an oral glycoprotein IIb/IIIa inhibitor in the Orbofiban in Patients with Unstable coronary Syndromes (OPUS-TIMI 16) trial. J Thromb Thrombolysis 2006;22:95-102
CrossRef | Web of Science | Medline
- Citing Articles (1)
Citing Articles
1
(2007) Current awareness: Pharmacoepidemiology and drug safety. Pharmacoepidemiology and Drug Safety 16:12, i-xii
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