L-carnitine can be measured accurately--and cost-effectively.
Rosenthal
Arthur F
AF
D002331:Carnitine / Q000097:blood* / Q000191:economics; D002623:Chemistry Techniques, Analytical / Q000191:economics / Q000379:methods* / Q000592:standards; D002851:Chromatography, High Pressure Liquid / Q000191:economics / Q000592:standards; D003362:Cost-Benefit Analysis; D017408:Guidelines as Topic; D006801:Humans; D007676:Kidney Failure, Chronic / Q000097:blood* / Q000628:therapy; D006435:Renal Dialysis
D002331:Carnitine