Reactive Thrombocytosis Related Cerebral Venous Thrombosis: A Rare Complication of Untreated Iron Deficiency Anemia

Thrombocytosis can be either primary or secondary, and it can cause venous pro-thrombotic states like cerebral venous thrombosis. Untreated iron deficiency anemia is postulated to cause reactive (secondary) thrombocytosis due to the proliferation of common progenitor cells. Here we present a case of a middle-aged woman with polycystic ovary syndrome and episodes of menorrhagia. She presented with headache and focal sensory deficits, and her neuroimaging showed evidence of cerebral venous sinus thrombosis (CVST). Laboratory tests showed microcytic hypochromic anemia, low ferritin, high total iron-binding capacity (TIBC), and thrombocytosis with a platelet count of 1,523,000/mm³. A comprehensive workup for hypercoagulable states and primary causes of thrombocytosis was negative. It was concluded that the etiology of her CVST was a reactive thrombocytosis from chronic untreated iron deficiency anemia. Anticoagulation with apixaban and corrective treatment for iron deficiency anemia was initiated. A repeated neuroimaging after four months showed significantly less clot burden in the cerebral venous sinuses, and then apixaban was stopped after six months. Laboratory tests after one year of iron replacement therapy showed improvement in the hemoglobin and hematocrit as well as normalization of platelet count. This case highlights a rare yet potentially dangerous complication of a common untreated condition, i.e., iron deficiency anemia.