Thrombocytosis in Chronic Inflammatory Bowel Disease

Six patients with either ulcerative or granulomatous intestinal disease were noted to have markedly elevated concentrations of circulating blood platelets during a period of increased clinical activity of their bowel disorders. The series included three males and three females, ranging in age from 13 to 52 years. Platelet counts were observed for periods varying from 37 to 89 days, and concentrations generally ranged between 500,000 and 1.3 million/mm³. Careful examination failed to disclose any primary hematologic disease, though granulocytic and megakaryocytic hyperplasia of the bone marrow were noted. Other factors capable of inducing thrombocytosis, such as anemia, iron deficiency, and active gastrointestinal bleeding, were not uniformly present.

Myelosuppressive therapy was used in three patients with the highest platelet concentrations in an effort to decrease the likelihood of hemorrhagic or thrombotic phenomena often associated with thrombocythemia. One patient with untreated thrombocytosis who underwent surgery demonstrated markedly increased bleeding, requiring numerous transfusions. No other cause of bleeding could be found. No thrombotic episodes were observed. The cause of the increased platelet concentrations is unknown but probably represents an exaggerated though nonspecific response of the bone marrow to chronic inflammation.