French experience of quality assessment of quantitative urinary analysis

Since 1986, clinical biochemists from the Rhone alpes area, in collaboratio n with a non-profit-making association (Pro Bio Qual), have been conducting an inter-laboratory quality assurance program for quantitative urine analy sis. We investigated the precision and accuracy of individual methods and m easurement systems routinely used in the monthly control for 13 analytes: a lbumin, cu-amylase, calcium, chloride, creatinine, glucose, magnesium, phos phorus, potassium, total protein, sodium, urea, and urate. The number of la boratories participating in the program increased from 60 in 1986 to 277 in 1999. In 1986, the greatest inter-laboratory imprecision occurred in the a ssay of urinary total protein, because the commonly used sulfosalicylic aci d turbidimetric methods displayed poor precision. Since 1989, the increasin g use of pyrogallol red or Coomasie Blue dye colorimetric methods has impro ved inter-laboratory precision markedly. The acceptable precision and good practicability have encouraged the general use of the pyrogallol red method . As for albumin analysis, which uses a specific immunologic method, the pr ecision was reasonably good. Quality assessment of chloride and sodium decr eased when the method performance improved for other analytes (calcium, cre atinine, glucose, magnesium, phosphorus, potassium, urea, urate). This prog ram has helped the laboratories to improve the quality of quantitative urin e analysis, particularly for total protein. (C) 2000 Elsevier Science B.V. All rights reserved.