Diagnostics
urine. This may result in a falsely decreased urine glucose measurement. Also, bacteria produce ammonia, which makes the urine more alkaline (increases pH). Finally, this increase in urine pH causes cells, like white blood cells, to degrade and may become unrecognisable.3 P. Froom et al 4
discovered that processing
large numbers of urinary samples that arrive late afternoon can lead to overnight refrigeration. After storage approximately 25% of the leucocyte esterase positive samples were less reactive. Precision of haemoglobin retests was also high but declined significantly after storage for 24 h. Urine protein values increased after storage. After refrigeration for 24 h, there is a risk of false-positive results for protein, false-negative results for leukocytes and erythrocytes. Temperature: Urinalysis should be performed
on room-temperature urine. The sample should be allowed to sit at room temperature for 30 minutes if urine was refrigerated before performing the urinalysis. Cold urine can cause a false increase in the urine specific gravity measurement potentially resulting in an incorrect diagnosis. Sample collection: Bacârea et al 5
noted
despite existing guidelines, the importance of the appropriate method for urine collection is not recognised by the patient and often not followed. Urine samples are not properly collected in more than half of cases even when they are previously instructed, and especially in elderly patients. Dipping technique: Incomplete dipping of the
dipstick can occur when there is a small volume of sample available or owing to the dimensions of the urine collection device (Fig. 2). Proper sample preparation: Including
carefully wiping the edge of the dipstick immediately after immersing in urine to ensure
colour results simultaneously. Furthermore, many of the other readout times are close together (within 10–30s), so the user must be able to quickly determine the results to maintain precise readout times.7 Degradation of reagents: A study by Crolla et
al 8
highlighted that the accuracy of urinalysis depends upon the integrity of the test strips used. False results and diagnoses can arise from degradation of test strip reagents through humidity, agnostic to brand. Although dipstick manufacturers state the capped vials containing the dipsticks must be closed immediately after removal of a strip, this recommendation may not always be followed in a busy department (Fig 3). E. J. Gallagher et al 9
discovered that after
Figure 2: Urine sample being tested with dipstick.
application of the correct volume on each pad and to prevent cross-contamination between adjacent pads that is common in the standard dip-and-wipe method.6
Dipsticks with various
volumes deposited onto each pad; using the incorrect volume to wet the dipstick pads can lead to erroneous results. Correct interpretation of gradient colour
scale: Interpretation of the gradient colour scale often requires the user to differentiate between various shades of the same colour, a difficult task for many people that can be exacerbated in certain lighting conditions. Additionally, the tests are inherently unreadable to users who are colour-blind.7 Precise readout timing: Each pad of the
dipstick must be read at a specific time to ensure accuracy, as the results vary over time. Several of the pads have the same readout time, requiring the user to interpret several
exposure to air for a week, one third of the dipstick nitrite tests gave false-positive readings. At the end of a second week, nearly three quarters gave false-positive readings, a specificity of only 28%. H. T. Cohen10
investigated
the impact of air exposure on dipstick accuracy. A urine sample reading negative for glucose tested trace positive with dipsticks exposed for 7 days, and 1+ when the sticks were exposed for 28 days. A urine sample reading 1+ for blood with fresh dipsticks tested negative after exposure for 28 and 56 days.
The introduction of urine dipstick analysers The introduction of urine dipstick analysers marked a significant improvement in urinalysis compared to traditional manual visual reading, offering several features and benefits that enhanced both diagnostic accuracy and patient care. Automatic reading eliminates the subjectivity inherent in manual interpretation, thereby improving consistency and reliability. The ability to check strips for humidity ensures that degraded reagents can be identified and discarded, allowing the test to be repeated under appropriate conditions. Bar code reading capability further
strengthens traceability, while connectivity enables seamless integration of results with the electronic patient record (EPR). In addition, the option to print reports and review paper copies locally facilitates documentation and clinical review. The operation of these analysers is simple and rapid, fitting efficiently into clinical workflows with minimal training requirements. Despite these advantages, certain limitations
Figure 3: Dipsticks with urine sample.
are associated with the use of urine analysers. Larger analysers are not easily portable due to their size and therefore may not be considered true point-of-care (POC) devices. Furthermore, most high-volume automated and semi- automated analysers require a direct mains power connection, reducing their flexibility
February 2026 I
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