Abstract:
Dipstick urinalysis, a rapid diagnostic method
is routinely used in clinical laboratories needs
preserved samples to provide accurate results when
test is not performed by two hours. This study
compared dipstick urinalysis with manual method
and identified the effects of storage on urine pH,
sugar and protein in an experimental and completely
randomized study. Randomization was used to
store urine samples in different storage times and
temperatures. Ninety-six mid-stream urine samples
in aliquots were stored at room temperature for 6
hours and 2-8°C for 6 and 24 hours to test urine pH,
glucose and protein. The manual methods for urine
pH, glucose and protein were pH meter, Benedict’s
test and turbidimetry respectively. Dipstick A, B
and C showed statistically significant difference
(p<0.01) when compared with manual method for
urine pH. The sensitivity, specificity, positive and
negative predictive values of dipstick A for the
detection of glucose were 77.8%, 100%, 100%, and
95.12% and for protein were 81.81%, 100%, 100%
and 91.30% respectively. No significant differences
between three dipsticks were found on urine
glucose and protein measurement. Statistically
significant increases were observed when samples
stored at room temperature for 6 hours (p<0.01)
and at 2-8°C for 24 hours (p<0.01). The changes
were not detected by dipstick (A) technique. Little
effect on urine sugar was found after storage at
room temperature for 6 hours and at 2-8oC for 24
hours in both methods (p>0.01). Urine protein
was preserved up to 6 hours at 2-8°C (p>0.01).
Significant increases were obtained on samples
stored at room temperature (p<0.01). There was a
risk of false positive results for protein tested using
dipstick ‘A‘ on stored samples. From this study,
dipstick A, B and C have a good diagnostic value
for urine sugar and protein and it is best to test on
fresh urine sample. If there is an unavoidable delay
it should be stored at refrigerator at 2-8°Cfor 6
hours.
