Complete Resolution of Unprovoked Left Renal Vein Thrombosis and Pulmonary Embolism Associated With Severe Iron Deficiency Anemia: A Five-Year Follow-Up Case Report and Dual-Energy CT Appraisal.

Combined renal vein thrombosis (RVT) and pulmonary embolism (PE) in young adults without nephrotic syndrome, malignancy, or an identified major thrombophilia is uncommon. Severe iron deficiency anemia (IDA) has been associated with increased thrombotic risk, although a causal relationship cannot be established from an individual case. A 21-year-old male patient presented with flank and chest pain. Diagnostic workup confirmed acute left RVT and an acute embolism of the posterior basal segmental artery of the right lower lobe with pulmonary infarction, concurrent with profound microcytic IDA (hemoglobin 5.7 g/dL, MCV 58 fL) attributed clinically to severe chronic active gastritis, with concomitant vitamin B12 and folate deficiency and reactive thrombocytosis. Available thrombophilia testing was negative, including Factor V Leiden mutation and anticardiolipin IgG/IgM antibodies. The patient was treated with intravenous iron, blood transfusions, therapeutic low-molecular-weight heparin, and subsequently rivaroxaban 20 mg daily. At five-year follow-up, dual-energy CT (DECT) demonstrated complete anatomical recanalization of the left renal vein, complete resolution of the PE, and uniform pulmonary perfusion without residual segmental perfusion defects. Prior reports linking IDA to unusual-site venous thromboembolism (VTE) have relied largely on short-term clinical follow-up. This case contributes structural and functional imaging confirmation obtained five years after the index event, providing longitudinal anatomical and perfusion evidence of complete recanalization that is not available in the existing IDA-VTE literature. This case illustrates an unusual combination of RVT, PE, and profound IDA in a young adult without an identified conventional provoking factor. Severe IDA, occurring alongside broader micronutrient deficiency, may have contributed to thrombotic risk in this patient, but causality cannot be established. Complete vascular recanalization and clinical stability were observed during long-term anticoagulation with rivaroxaban and correction of the hematologic abnormalities.