Mayo Clinic recently completed a four-year review of Myasthenia Gravis serum evaluations and will be implementing changes to our testing algorithm.
Why the changes:
• Increase diagnostic specificity while maintaining high sensitivity – 90% sensitive, 95% specific
• Simplify ordering
• Improve turn-around-time
Research findings are published in Neurology and available online by clicking on this title: “Improving accuracy of myasthenia gravis autoantibody testing by reflex algorithm”
• Accuracy of MG serological testing is improved by reflexing acetylcholine-receptor-binding (AChR-Bi) positive cases to acetylcholine-receptor-modulating (AChR-Mo)
• Striational (STR) and other reflexed cancer evaluation autoantibodies (GAD65, Alpha-3, CRMP5 and VGKC) did not provide value beyond CT-chest imaging
• MG patients negative for AChR-Bi and AChR-Mo most often have muscle-specific receptor tyrosine kinase (MuSK) autoantibodies present
Difference from old method will involve:
• Initial testing for AChR-Bi only (eliminates up-front testing for AChR-Mo and STR)
• Automatic reflex to MUSK when AChR-Bi is negative to improve turn-around time
• Automatic reflex to AChR-Mo when AChR-Bi is positive to reduce false positives
• The AChR-Mo assay method will change from a quantitative bioassay to qualitative FACS live CBA
• Eliminate reflex to “paraneoplastic” antibodies (GAD65, Alpha-3, CRMP5 and VGKC)
In short, if the AChR-binding is positive, AChR-modulating will be performed. If AChR-binding is negative, MuSK will be performed.
This change will go into effect on May 11, 2021. Please direct questions and inquiries to the Referral/Sendout Department via the “contact us” link above.
