Extensive Proximal Deep Vein Thrombosis Despite Normal Age-Adjusted D-Dimer Levels: A Case Report

Deep vein thrombosis (DVT) refers to the formation of a blood clot within a deep vein, most often in the lower extremities, which can partially or completely obstruct venous blood flow. This case discusses a 93-year-old female nursing home resident who developed extensive left lower limb swelling with a laboratory D-dimer level of 316 ng/mL (normal range for a 93-year-old: 0-930 ng/mL). Based on her age-adjusted D-dimer threshold of 930 ng/mL, thrombosis would ordinarily be considered unlikely. However, given her predominantly wheelchair-bound status and a Wells score of 3, the clinical suspicion for DVT remained high. Doppler ultrasound subsequently confirmed extensive proximal thrombosis with complete occlusion of the left popliteal and femoral veins. This case illustrates the limitations of relying solely on D-dimer testing to exclude DVT in elderly patients and underscores the importance of clinical judgment.