10 Spanish laboratories used commutable controls with reference method values.
10 out of the 26 analytes studied did not have comparable results. Reasons were.
Use of non-standard methods for AST and ALT, and Jaffé for creatinine and eGFR.
Routine calibrators traceable to non-commutable standards (calcium, magnesium, sodium).
Use of reference materials instead of reference methods for AST and GGT.