We use cookies to understand how you use our site and to improve your experience. This includes personalizing content and advertising. To learn more, click here. By continuing to use our site, you accept our use of cookies. Cookie Policy.

Features Partner Sites Information LinkXpress hp
Sign In
Advertise with Us
LGC Clinical Diagnostics

Download Mobile App




Drug Causes Missed Diagnosis of Protein S Deficiency

By LabMedica International staff writers
Posted on 01 Jan 2018
Rivaroxaban is a direct, antithrombin-independent factor Xa inhibitor, which inhibits not only free factor Xa, but also clot-bound factor Xa and the prothrombinase complex. More...
It is used for treatment and prevention of venous thromboembolism, as well as for prophylaxis of stroke in patients with atrial fibrillation.

Many patients taking rivaroxaban undergo hypercoagulation testing to rule out common inherited or acquired causes of hypercoagulability, including assays for activated protein C resistance (APCR) to detect factor V Leiden (FVL), and tests for protein S deficiency. However, it has been reported that spiking normal plasma with rivaroxaban caused an artefactual increase in the APCR ratio.

Scientists at Massachusetts General Hospital (Boston, MA, USA) compared of 60 patients in four different groups: FVL heterozygous (FVL-HET)/taking rivaroxaban, wild-type/taking rivaroxaban, FVL-HET/no rivaroxaban, and normal APCR/no rivaroxaban, and 32 patients taking rivaroxaban were tested for protein S functional activity and free antigen.

The patients were evaluated using the standard FVL testing protocol: an activated partial thromboplastin time (aPTT)-based APCR assay with dilution in factor V–deficient plasma on a Star Evolution analyzer and an FVL DNA assay. Protein S functional activity was measured using the Stago STACLOT Protein S assay on a Star Evolution analyzer, and free protein S antigen was measured using the Stago Asserachrom Free Protein S.

The team found that the FVL-HET patients taking rivaroxaban had lower APCR ratios than wild-type patients. For FVL-HET patients taking rivaroxaban, mean APCR was 1.75 ± 0.12, versus 1.64 ± 0.3 in FVL-HET patients not taking rivaroxaban. Activated protein C resistance in FVL-HET patients fell well below the cutoff of 2.2 at which the laboratory reflexes FVL DNA testing. No cases of FVL were missed despite rivaroxaban, but in contrast, rivaroxaban falsely elevated functional protein S activity, regardless of the presence or absence of FVL. A total of 4/32 patients (12.5%) had low free protein S antigen (range, 58%–67%), whereas their functional protein S activity appeared normal (range 75%–130%).

The authors concluded that despite rivaroxaban treatment, APCR testing can distinguish FVL-HET from normal patients, rendering indiscriminate FVL DNA testing of all patients on rivaroxaban unnecessary. Free protein S should be tested in patients taking rivaroxaban to exclude hereditary protein S deficiency. The study was published in January 2018 in the journal Archives of Pathology & Laboratory Medicine.

Related Links:
Massachusetts General Hospital


New
Gold Member
Thyroid-Stimulating Hormone Test
ULTRA-TSH
Verification Panels for Assay Development & QC
Seroconversion Panels
New
Mumps Test
ReQuest MUMPS IgM Assay
New
Nutating Mixer
Enduro MiniMix
Read the full article by registering today, it's FREE! It's Free!
Register now for FREE to LabMedica.com and get access to news and events that shape the world of Clinical Laboratory Medicine.
  • Free digital version edition of LabMedica International sent by email on regular basis
  • Free print version of LabMedica International magazine (available only outside USA and Canada).
  • Free and unlimited access to back issues of LabMedica International in digital format
  • Free LabMedica International Newsletter sent every week containing the latest news
  • Free breaking news sent via email
  • Free access to Events Calendar
  • Free access to LinkXpress new product services
  • REGISTRATION IS FREE AND EASY!
Click here to Register








Channels

Clinical Chemistry

view channel
Image: The POC device rapidly predicts neonatal respiratory disease at birth in the NICU (Photo courtesy of SIME Diagnostics)

AI-Powered Lung Maturity Test Identifies Newborns at Higher Risk of Respiratory Distress

Each year, approximately 300,000 babies in the United States are born between 32 and 36 weeks' gestation, according to national health data. This group is at an elevated risk for respiratory distress,... Read more

Immunology

view channel
Image: The cancer stem cell test can accurately choose more effective treatments (Photo courtesy of University of Cincinnati)

Stem Cell Test Predicts Treatment Outcome for Patients with Platinum-Resistant Ovarian Cancer

Epithelial ovarian cancer frequently responds to chemotherapy initially, but eventually, the tumor develops resistance to the therapy, leading to regrowth. This resistance is partially due to the activation... Read more

Pathology

view channel
Image: A biomarker discovery pipeline has shown promise as a noninvasive method of diagnosing CRC (Photo courtesy of NCI Center for Cancer Research)

Machine Learning Tool Enables Noninvasive Diagnosis and Monitoring of Colorectal Cancer

Colorectal cancer (CRC) is the second leading cause of cancer-related deaths in the United States when considering both genders. Colonoscopy remains the gold standard for CRC diagnosis, but it is invasive,... Read more

Technology

view channel
Image: Scanning electron microscopy images showing 3D micro-printed Limacon-shaped whispering-gallery-mode microcavities with different amounts of deformation (Photo courtesy of A. Ping Zhang/PolyU)

Tiny Microlaser Sensors with Supercharged Biosensing Ability to Enable Early Disease Diagnosis

Optical whispering-gallery-mode microlaser sensors function by trapping light within tiny microcavities. When target molecules bind to the cavity, they induce subtle changes in the laser’s frequency, allowing... Read more
Copyright © 2000-2025 Globetech Media. All rights reserved.