-The preanalytic phase of 24-hour urine collection, before clinical analysis, requires the active participation of patients and usually takes place outside the laboratory.
-We verify whether distribution of adequate information to health care personnel and patients will result in fewer preanalytic incidents. We also determine the intraindividual biologic variability associated with micturition and the corresponding reference change value (RCV).
-The intervention provided training for 24-hour urine collection to the health care personnel of the 20th health district of the Valencian community in Spain. The preanalytic incidents related to 24-hour micturition were estimated before and after the intervention. An opinion survey on the problems involved in urine collection was also conducted among patients. The Harris formula was used to calculate the RCV.
-Before the intervention, 130 preanalytic incidents were recorded (11.5%) and after the intervention, 76 (8.6%) (P = .04) were recorded. Of the 130 incidents recorded before the intervention, 63 (48.5%) involved omission to indicate the urine volume, and of the 76 incidents recorded after the intervention, only 1 (1.3%) (P < .001) involved this omission. Forty of 302 patients (13.2%) surveyed reported problems and more than half (175; 57.9%) had to collect various urine samples sequentially. The RCV determined was 54.5% for a percentage of variation in volume of 24-hour urine (PVVI) of 19.0 +/- 16.5%. Therefore, micturition associated with a PVVI >+/-54.5% suggests that 24-hour urine collection by the patient was incomplete. The results obtained when applying the RCV after the intervention showed that 6.3% of the 24-hour urine samples should be rejected.
-The percentage of preanalytic incidents was reduced by providing health care personnel with information and training. The percentage of variation in volume of 24-hour urine can be used to evaluate the variation in patients' micturition. Reference change value was shown to be useful when determining whether 24-hour urine was properly collected.