From D. Kaguni:
I would like to know where I would find information on validation of a rare factor activity assay in which the test kit is quite expensive and performing the recommended 120 normal plasmas to create a reference range would be very expensive. I have inquired with CLSI and they do not have definitive guidelines concerning a situation like this. Thank you for your assistance.
Hello, D. Kaguni, and thank you for your question. This issue is addressed by CLSI: How to Define and Determine Reference Intervals in the Clinical Laboratory; Approved Guideline—Third Edition. CLSI document C28-A3. CLSI, 940 West Valley Road, Suite 1400, Wayne, Pennsylvania 19087-1898, USA 2008. For most factor assays there is a published reference interval that you need only validate through transference, which requires 20 normal specimens. Transference provides a way to locally validate published reference intervals. The specification for 120 normal specimens is reserved for new analytes. The Guideline provides instructions for subject selection, specimen management, and statistical validation. I hope this is helpful. Geo.