alt Hacker NewsI did end up taking a cystatin c test privately to be able to prove to my GP that the results he freaked out over were nonsense. I'm in the UK, and for whatever reason the NHS just doesn't typically do them for basic kidney function - presumably cost, but they were dirt cheap to do privately so...
NICE guidelines. "Evidence on the specific eGFR equations or ethnicity adjustments seen by the committee was not from UK studies so may not be applicable to UK black, Asian and minority ethnic groups. None of the studies included children and young people. The committee was also concerned about the value of P30 as a measure of accuracy (P30 is the probability that the measured value is within 30% of the true value), the broad range of P30 values found across equations and the relative value or accuracy of ethnicity adjustments to eGFR equations in different ethnic groups. The committee agreed that adding an ethnicity adjustment to eGFR equations for different ethnicities may not be valid or accurate...."
https://www.nice.org.uk/guidance/ng203/chapter/rationale-and...