Thrombocytosis Associated with Low-Molecular-Weight Heparin

TO THE EDITOR:

A 67-year-old woman with adrenal cortical carcinoma had nephrectomy, adrenalectomy, inferior vena cava thrombectomy, splenectomy, and liver wedge biopsy. Surgical margins were clear of tumor, but examination of a liver biopsy specimen showed the presence of cancer. Four months after these procedures were done, scans of the abdomen showed progressive disease in the liver. The patient was then referred for chemotherapy. While hospitalized, she experienced acute shortness of breath during the first cycle of cisplatin and etoposide. Spiral computed tomography showed a tumor and bilateral pulmonary thrombus. Therapy with low-molecular-weight heparin was initiated, and the patient's platelet count was 285 cells/mm³. Two weeks later, the platelet count was 242 cells/mm³, but it then increased to 1114 cells/mm³ after 4 weeks of enoxaparin therapy. No other recent changes had been made in the patient's other medications, which included ranitidine, metoclopramide, dexamethasone, and vitamins. Enoxaparin therapy was discontinued and warfarin therapy was initiated while the patient received a second cycle of chemotherapy. Within 1 week, her platelet count decreased to 297 cells/mm³; within 1 month, however, it increased to 395 cells/mm³. Four months later, after two more cycles of chemotherapy and no disease progression, her platelet count was 355 cells/mm³.