Before analysis each sample was warmed to 37 #{176}C for at
least 30 mm, carefully mixed, diluted with 0.15 mol/L sodium
chloride so as to contain 5 zmol of creatinine per milliliter,
then filtered through a 0.22-tim filter (GS; Millipore Corp.,
Bedford, MA 01730). Excessive bacterial contamination was
excluded by means of a Uriglox-test (Kabi Diagnostica,
Stockholm, Sweden).