Measurement of urinary constituents with the Astra-8 Multichannel Analyzer

The Beckman Astra-8 is a computerized, discrete-microsample, multiple-test clinical chemistry analyzer. We have examined its capability to measure urine Na+, K+, Cl-, urea nitrogen, glucose, and creatinine and found that (a) the Astra measurements are linear, accurate, and precise in concentration ranges of urine analytes; (b) urine analyte concentrations measured with the Astra correlate well with those by comparison micromethods (p < 0.001); and (c) the Astra has no significant carryover from adjacent urine samples or from adjacent urine and serum samples.