Editing Reduction of Risk Potential (section)

=== Coagulation Studies ===

;Prothrombin time, approximately 11 to 12.5 seconds; international normalized ratio, approximately 0.8 to 1.1 untreated
Monitors '''warfarin''', which affects the extrinsic pathway and vitamin K dependent factors. Usual therapeutic international normalized ratio for atrial fibrillation and venous thromboembolism is about 2.0 to 3.0, and about 2.5 to 3.5 for many mechanical valves. Antidote: '''vitamin K (phytonadione)'''. Nursing application: teach consistent, not absent, dietary vitamin K intake, and review interacting drugs, especially antibiotics, amiodarone, and nonsteroidal anti-inflammatory drugs (Harding et al., 2023; Pagana et al., 2022).

;Activated partial thromboplastin time, approximately 30 to 40 seconds
Monitors '''unfractionated heparin''', which affects the intrinsic pathway. Therapeutic range is generally 1.5 to 2.5 times the control value. Antidote: '''protamine sulfate'''. Low molecular weight heparin such as enoxaparin does not require routine activated partial thromboplastin time monitoring. Nursing application: monitor the platelet count for heparin-induced thrombocytopenia, suspected when platelets drop substantially after several days of heparin, which paradoxically causes thrombosis; heparin must be stopped, and the client must not receive low molecular weight heparin as a substitute (Harding et al., 2023; Pagana et al., 2022).

;D-dimer
Elevated with active clot breakdown, as in pulmonary embolism, deep vein thrombosis, and disseminated intravascular coagulation. It is sensitive but not specific and rises with surgery, trauma, pregnancy, malignancy, and advanced age (Pagana et al., 2022).