Department of Laboratory Medicine
University of Washington
 
Clinical assay interference and limitations

Methodology: Stago STA LIA Free Protein S antigen assay

Specimens from patients who have received preparations of mouse monoclonal antibodies for diagnosis or therapy may contain human anti-mouse antibodies (HAMA). Such specimens may show either falsely elevated or depressed values when tested with assay kits which employ mouse monoclonal antibodies. Please contact the Laboratory Medicine Resident on call 598-6190 if you have questions about free protein S antigen levels in measured in a patient that has received preparations of mouse monoclonal antibodies.

Patients on coumadin therapy may see a decrease in Protein S free antigen because of the vitamin K antagonistic effect of the drug. Protein S is a vitamin K dependent factor.

Reference: Stago assay package insert, Cat. No. 00516 - Revised December 2000

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Created: February 28, 2002
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