[{"data":1,"prerenderedAt":-1},["ShallowReactive",2],{"doc-seo-453256-105":3,"detail-sidebar-cat-0-en-105":81,"doc-detail-453256-en":130},{"code":4,"msg":5,"data":6},0,"ok",{"site_id":7,"language":8,"slug":9,"title":10,"keywords":11,"description":12,"schema_data":13,"social_meta":74,"head_meta":76,"extra_data":78,"updated_unix":80},105,"en","marked-inr-elevation-associated-with-cefazolin-a-case-report","Marked INR Elevation Associated with Cefazolin - A Case Report","","Cefazolin is not commonly linked to increased bleeding risk; however, rare reports describe cefazolin causing vitamin-K-responsive coagulopathy. The case involves a patient with MSSA endocarditis who developed an abrupt, significant INR surge after starting cefazolin without vitamin K antagonist or azole exposure. A single oral vitamin K dose rapidly normalized the INR, but later the INR rebounded to supratherapeutic levels, requiring ongoing daily low-dose vitamin K. After readmission, normal INR persisted on cefazolin plus supplementation, supporting proactive monitoring.",{"@graph":14,"@context":73},[15,34,56],{"@type":16,"itemListElement":17},"BreadcrumbList",[18,23,27,31],{"item":19,"name":20,"@type":21,"position":22},"https://docshare.wps.com","Home","ListItem",1,{"item":24,"name":25,"@type":21,"position":26},"https://docshare.wps.com/document/","Document",2,{"item":28,"name":29,"@type":21,"position":30},"https://docshare.wps.com/document/healthcare/","Healthcare",3,{"item":32,"name":10,"@type":21,"position":33},"https://docshare.wps.com/document/marked-inr-elevation-associated-with-cefazolin-a-case-report/453256/",4,{"url":32,"name":10,"@type":35,"image":36,"author":41,"headline":10,"publisher":44,"fileFormat":47,"inLanguage":8,"description":12,"dateModified":48,"datePublished":49,"encodingFormat":47,"isAccessibleForFree":50,"interactionStatistic":51},"DigitalDocument",{"url":37,"@type":38,"width":39,"height":40},"https://docshare.wps.com/thumbnails/marked-inr-elevation-associated-with-cefazolin-a-case-report/453256.png","ImageObject",300,407,{"name":42,"@type":43},"Ivy","Person",{"url":19,"name":45,"@type":46},"DocShare","Organization","application/pdf","2026-10-30","2026-09-30",true,{"@type":52,"interactionType":53,"userInteractionCount":55},"InteractionCounter",{"@type":54},"ViewAction",10,{"@type":57,"mainEntity":58},"FAQPage",[59,65,69],{"name":60,"@type":61,"acceptedAnswer":62},"Why is cefazolin associated with INR elevation in this case despite no warfarin exposure?","Question",{"text":63,"@type":64},"The report describes a vitamin-K-responsive coagulopathy that occurred independently of warfarin, likely linked to cefazolin’s effects on the vitamin K pathway and/or intestinal vitamin K production.","Answer",{"name":66,"@type":61,"acceptedAnswer":67},"How was the INR elevation managed once it reached supratherapeutic levels?",{"text":68,"@type":64},"A single 5 mg oral dose of vitamin K was given, which reduced the INR rapidly. Because the INR later rebounded above target, the patient required a daily low-dose oral vitamin K1 regimen to maintain suppression of INR elevation.",{"name":70,"@type":61,"acceptedAnswer":71},"What clinical factors supported the mechanism involving reduced vitamin K reserves?",{"text":72,"@type":64},"The case included low vitamin K reserve markers and impaired nutritional status at the time of INR elevation, supported by plasma vitamin K testing and low pre-albumin.","https://schema.org",{"og:url":32,"og:type":75,"og:title":10,"og:site_name":45,"og:description":12},"article",{"robots":77,"canonical":32},"index,follow",{"doc_id":79,"site_id":7},453256,1790812080,{"code":4,"msg":82,"data":83},"success",[84,88,92,96,101,106,110,115,120,123,126],{"id":22,"doc_module":4,"doc_module_name":25,"category_name":85,"show_sort_weight":86,"slug":87},"Story & Novel",90,"story-novel",{"id":26,"doc_module":4,"doc_module_name":25,"category_name":89,"show_sort_weight":90,"slug":91},"Literature",80,"literature",{"id":33,"doc_module":4,"doc_module_name":25,"category_name":93,"show_sort_weight":94,"slug":95},"Exam",70,"exam",{"id":97,"doc_module":4,"doc_module_name":25,"category_name":98,"show_sort_weight":99,"slug":100},5,"Comic",60,"comic",{"id":102,"doc_module":4,"doc_module_name":25,"category_name":103,"show_sort_weight":104,"slug":105},6,"Technology",50,"technology",{"id":107,"doc_module":4,"doc_module_name":25,"category_name":29,"show_sort_weight":108,"slug":109},7,40,"healthcare",{"id":111,"doc_module":4,"doc_module_name":25,"category_name":112,"show_sort_weight":113,"slug":114},8,"Research & Report",30,"research-report",{"id":116,"doc_module":4,"doc_module_name":25,"category_name":117,"show_sort_weight":118,"slug":119},9,"Religion & Spirituality",20,"religion-spirituality",{"id":118,"doc_module":4,"doc_module_name":25,"category_name":121,"show_sort_weight":118,"slug":122},"World Cup","world-cup",{"id":55,"doc_module":4,"doc_module_name":25,"category_name":124,"show_sort_weight":55,"slug":125},"Lifestyle","lifestyle",{"id":127,"doc_module":4,"doc_module_name":25,"category_name":128,"show_sort_weight":97,"slug":129},19,"General","general",{"code":4,"msg":82,"data":131},{"doc_id":79,"user_id":132,"nickname":42,"user_avatar":133,"doc_module":4,"category_id":107,"category_name":29,"doc_title":10,"doc_description":12,"doc_content":134,"file_id":135,"file_url":136,"file_type":137,"file_size":138,"view_count":55,"is_deleted":4,"is_public":22,"is_downloadable":22,"audit_status":22,"page_count":33,"language":139,"language_code":8,"site_id":7,"html_lang":8,"table_of_contents":140,"faqs":141,"seo_title":142,"seo_description":12,"update_tm":143,"read_time":55,"preview_page_count":4},549758252649,"https://ap-avatar.wpscdn.com/avatar/8000253669c5317157?_k=1778319167496531819","Marked INR Elevation Associated with Cefazolin: A Case Report  \nBryce Beckstrom 1, Richard Wong2, and Tiffany LaDow2  \nHospital Pharmacy  \n1–4 © The Author(s) 2026  \nArticle reuse guidelines:  \n[sagepub.com/journals-permissions](sagepub.com/journals-permissions)[ ](sagepub.com/journals-permissions)[DOI: 10.1177/00185787251405375](DOI: 10.1177/00185787251405375)[ ](DOI: 10.1177/00185787251405375)[journals.sagepub.com/home/hpx](journals.sagepub.com/home/hpx)  \nAbstract  \nCefazolin is not typically considered to be an antibiotic that can increase the risk of bleeding. Yet, rare cases of cefazolin independently inducing a vitamin-K-responsive coagulopathy have been described. We report a patient with methicillinsusceptible Staphylococcus aureus (MSSA) endocarditis who developed an abrupt and significant international normalized ratio (INR) surge on cefazolin in the absence of exposure to vitamin K antagonists or azoles. Although the administration of a single dose of oral vitamin K rapidly corrected the INR elevation, the INR rebounded to supratherapeutic range later in the hospital course and ultimately required a daily low-dose vitamin K regimen to suppress the INR elevation. Upon readmission, the patient’s INR remained normal while on the combination of cefazolin and vitamin K supplementation. This case underscores that cefazolin can precipitate a clinically meaningful, vitamin-K-responsive INR elevation—especially in patients with renal dysfunction and low vitamin K reserve—and that proactive monitoring and supplementation may be warranted. Prior reports and mechanistic data are reviewed.  \nKeywords  \nadverse drug reactions, reporting/monitoring, anti-infectives, blood, infectious diseases, medication safety  \nIntroduction  \nCefazolin is a first-generation cephalosporin used widely for definitive treatment of MSSA infections and is particularly effective in treating bacteremia and endocarditis.1 INRdependent coagulopathy with cefazolin is generally attributed to its potential interactions with warfarin. However, cases have been reported where cefazolin monotherapy, in the absence of warfarin, has induced hypoprothrombinemia with prolonged prothrombin time (PT), INR, and, in some cases, bleeding.2-5 These laboratory abnormalities often necessitate vitamin K administration and may compel discontinuation or substitution ofcefazolin. Although the mechanism for cephalosporin-associated hypoprothrombinemia is classically linked to agents with an N-methyl-thiotetrazole (NMTT) side chain, cefazolin lacks NMTT. Alternatively, the mechanism for cefazolin-induced coagulopathy may be due to the inhibition of the vitamin K epoxide reductase pathway by cefazolin’s methyl-thiadiazole (MTD) side chain and suppression of intestinal vitamin K production.6-10 Evidence focused specifically on cefazolin is limited; nearly all cases are diagnosed by temporal association with cefazolin exposure, improvement after cessation and/or vitamin K, and exclusion of alternate causes such as hepatic dysfunction, disseminated intravascular coagulation, or anticoagulant use.2-5 We report the case of a marked INR elevation  \ninvolving cefazolin in the absence of warfarin in a patient with MSSA endocarditis which was corrected rapidly with vitamin K replacement and subsequently maintained on lowdose oral vitamin K supplementation.  \nCase Presentation  \nA 52-year-old female was admitted with fever, hyperglycemia, and suspected sepsis. Initial evaluation revealed leukocytosis and acute-on-chronic kidney disease. Blood cultures grew MSSA, and echocardiography demonstrated mitral valve endocarditis with perivalvular extension. The neurology team noted scattered small intracranial hemorrhages consistent with septic emboli. The cardiothoracic surgery team considered surgical intervention for source control of the vegetation, but ultimately this was deferred due to the patient’s unstable condition and the risk of exacerbating the intracranial hemorrhage with perioperati","cbCailCxFTJW8xfV","https://ap.wps.com/l/cbCailCxFTJW8xfV","pdf",477452,"English","# Abstract\n# Keywords\n# Introduction\n# Case Presentation\n## Clinical background and diagnostics\n## Anticoagulation considerations and therapy course\n## INR trend and vitamin K response","[{\"question\":\"Why is cefazolin associated with INR elevation in this case despite no warfarin exposure?\",\"answer\":\"The report describes a vitamin-K-responsive coagulopathy that occurred independently of warfarin, likely linked to cefazolin’s effects on the vitamin K pathway and/or intestinal vitamin K production.\"},{\"question\":\"How was the INR elevation managed once it reached supratherapeutic levels?\",\"answer\":\"A single 5 mg oral dose of vitamin K was given, which reduced the INR rapidly. Because the INR later rebounded above target, the patient required a daily low-dose oral vitamin K1 regimen to maintain suppression of INR elevation.\"},{\"question\":\"What clinical factors supported the mechanism involving reduced vitamin K reserves?\",\"answer\":\"The case included low vitamin K reserve markers and impaired nutritional status at the time of INR elevation, supported by plasma vitamin K testing and low pre-albumin.\"}]","Marked INR Elevation Associated with Cefazolin - A Case Report | PDF",1790738564]