From Kerri Klemm: Has anyone had problems recently with ristocetin-induced platelet aggregation? We have used this reagent for years and just recently had problems. We run the ristocetin at 1.5 mg, which should react and does and 0.75 mg, which shouldn’t react but does. This is with our normal controls who we have used before. Until recently we got the expected reactions but now everyone reacts at 0.75. We tried a different brand and it seems to work better. But the brand we were using we started using a few years ago when the previous brand did the same thing. This has happened with different patients and controls and every tech in the department. Any insight would be greatly appreciated.
Thank you, Kerri, I’ve not heard of any problems, however we are likely to hear from some of our participants. Geo
It is possible to have Ristocetin no aggregation or no respo
It is possible to have Ristocetin no aggregation or no response in Glanzmann Thrombasthenia. It is not diagnostic +/-. Please refer to Saunders Manual of Clinical Lab Science chapter 40, page 981.
I contacted Kathy Jacobs, Sales Coordinator at Chronolog Cor
I contacted Kathy Jacobs, Sales Coordinator at Chronolog Corporation, Havertown, PA, about this ristocetin question. Chronolog is the major supplier of ristocetin in the US. Here is Kathy’s response:
Very nice to hear from you and thank you for sending us this information. Your message comes at a very good time as we are expecting a new lot of ristocetin. I will be testing it against our current lot and will test some additional concentrations and let you know how it looks. Kathy.
Hi George and Kerri. In our laboratory we use 4 concentrati
Hi George and Kerri. In our laboratory we use 4 concentrations of Ristocetin (BioData). The concentrations we use are 1.2, 1.0, 0.75 and 0.50. Additional testing, based on the results from those concentrations, we may include 1.5 or 0.25.
Our reference range for 0.75 is lower than that of 1.2 and 1.0 but obviously higher than the 0.50 concentration. Additionally, it varies from time to time on the same control. I know this because I am a normal control donor and depending on any number of factors of which I have no idea about, my agglutination studies using 0.75 ristocetin vary significantly, but 1.0 always strongly agglutinates and 0.50 never does. Most of our other normal control donors show the same type of response.
If this is a major shift that is causing concern, you may consider the instrument itself as the source of the problem. BioData recommends sending instruments back to them periodically for “recertification” and they will provide a loaner during your instruments vacation.
St. Louis University Coagulation Reference Laboratory