We present the case of a 19-year-old male athlete with protein C deficiency who developed proximal deep venous thrombosis and pulmonary embolism while abusing anabolic-androgenic steroids. Anabolic-androgenic steroids have been reported to have anticoagulatory and profibrinolytic effects in patients with protein C deficiency. Despite these antithrombotic effects, the patient developed repeated venous thromboembolism during treatment with low-molecular-weight heparin. The net effect of anabolic-androgenic steroids on the haemostatic system may change from antithrombotic to prothrombotic in male abusers of anabolic steroids with protein C deficiency.
