Background
: The Urinalysis is useful laboratory test in the diagnosis of various diseases. But in many cases, the urine specimen is delayed in room temperature. There are some studies how the result changes with delayed specimen, but there are few study how much change occurs. So this study was carried out to determine the extent of change of delayed urinalysis.

Methods : During July and September 1991, the each urine specimen from medical outpatient department of Incheon Hospital was divided in equal amount and one was examined within 1 hour in fresh state and the other was examined about 4 to 6 hours after collection. The delayed urinalysis results were compared with fresh urinalysis results. Considering fresh urinalysis results as gold standard, the sensitivity and specificity of delayed urinalysis were calculated.

Results : Comparison of dipstick results showed no difference in specific gravity, protein, glucose and occult blood between the delayed specimens and the fresh specimens, but pH was increased significantly(p=0.001). The number of RBC(p=0.03), WBC(p=0.01), and epithelial cell(p=0.001) decreased significantly. The specificity of dipstick and microscopic examination results were above 90%, but sensitivity of all item below 90%. With the specimens resulted positive, there was no significant difference in glucose, protein, occult blood and WBC. But the number of RBC(p=0.012), and the number of epithelial cell(p=0.006) decreased significantly.

Conclusion : In some items, there was no significant difference statistically. But because the pH and the microscopic examination results changed significantly and sensitivity was below 90%, delayed urinalysis can lead to incorrect clinical decision-making. So we reaffirm that the urinalysis must be done with fresh urine specimen.
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