A patient has been taking Coumadin for a recent thrombophilic episode. He follows up with his physician two weeks after starting this treatment. The physician sees evidence of skin necrosis on the patient. What should the physician do next to investigate this finding?

Question

Quizplus · Accepted Answer

Skin necrosis is a rare but serious side effect of Coumadin use, known as Coumadin-induced skin necrosis (CISN). It occurs due to rapid depletion of protein C and protein S, which are vitamin K-dependent anticoagulants. Therefore, the physician should investigate the patient's protein C levels by requesting a Protein C antigen assay. This test measures the amount of protein C circulating in the blood and can help identify a deficiency that may contribute to CISN. PT and APTT measure the clotting time of blood and do not specifically test for protein C or protein S levels. HC-II antigen assay tests for the presence of heparin cofactor II, which can inhibit thrombin activity and is not directly related to CISN.

A Patient Has Been Taking Coumadin for a Recent Thrombophilic