Performance of quantitative urine analysis in Australasia critically assessed

The standard of quantitative urine analysis in Australasia has been assessed over a three-year period (1984-1986) through a national interlaboratory quality-assurance program, conducted jointly by the Royal College of Pathologists of Australasia and the Australian Association of Clinical Biochemists. We investigated the precision and accuracy of individual methods and measurement systems routinely used in 14 urine assays. Assays of sodium, potassium, creatinine, glucose, and chloride were performed satisfactorily. Further improvement is required in assays of urinary osmolality, phosphate, and 5-hydroxyindoleacetic acid. Determinations of oxalate, urea, calcium, and 4-hydroxy-3-methoxymandelic acid are improving, but assays of protein and urate in urine present major problems for Australasian laboratories. In this program the sulfosalicylic acid turbidimetric method for urinary protein has consistently displayed poor precision plus a significant positive bias and should be abandoned. In contrast, the trichloroacetic acid-Ponceau S manual method has continued to perform well.