Disseminated intravascular coagulation (DIC) is a consumptive coagulopathy associated with multiple conditions. Diagnosis is based upon clinical and laboratory findings with assessment of fibrinogen, platelets, D-dimer, prothrombin time/international normalized ratio and activated partial thromboplastin time. Herein, we report a case of a 39-year-old female patient diagnosed with endocarditis complicated by pulmonary septic emboli. For anticoagulation, the patient initially was treated with a heparin drip, but the patient remained subtherapeutic despite increasing dosage. The patient was transitioned to argatroban and developed an acute drop in the fibrinogen level. With concern for possible DIC, argatroban was held with a repeat panel six hours later revealing a significantly improved fibrinogen level. It was discovered that the Clauss method, which measures the capability of fibrinogen to form a clot after a high concentration of thrombin is added to diluted plasma, was used to measure fibrinogen at our institute. Argatroban may falsely reduce measured fibrinogen levels in vitro, caused by this method.Copyright © 2020, Ajmeri et al.