Nordic surveys of analytical quality in clinical chemistry laboratories.

The design of the 1979 revision of the Nordic interlaboratory survey of analytical quality is described. Two Nordic surveys have been run with the new scheme (in 1979 and 1980). State of the art data (intralaboratory imprecision and total variation) is presented and compared with previous Nordic survey results and with analytical goals (Aspen). The analytical bias of sodium, potassium, chloride, creatinine, urea, glucose, and cholesterol was estimated by comparison with highly accurate reference methods (neutron activation, isotope dilution mass spectrometry).