A comparison of urine dipstick test with spot urine protein-creatinine ratio and 24-hour urine protein excretion in women with preeclampsia

Background: Measurement of protein excretion in a 24-hour urine collection and measurement of protein-creatinine (P/C) ratio in a spot urine sample have been standard investigations for evaluation of protein excretion. The urine dipstick method, a semi-quantitative method of proteinuria excretion, has long been used as a screening tool for the same purpose. The objective of this study was to assess the efficacy of test dipstick measurement of proteinuria in comparison with 24 hour urinary protein excretion and spot urine protein/creatinine ratio, as a screening test in pregnant patients with suspected preeclampsia, attending an obstetric outpatient service.Methods: We measured proteinuria in 75 patients attending the obstetric outpatient service at our University Hospital by test dipstick method, 24-hour urine protein excretion and spot urine protein/creatinine ratio and calculated the degree of correlation between the first with the other two standard tests.  Results: The correlation of the urine dipstick test values with the 24-hour urine protein excretion was strong (r = 0.634), while compared to the spot urine protein/creatinine ratio, it was moderate at best (r = 0.401). The 1 + level of urine dipstick demonstrated greater sensitivity, but at the 2 + level, dipstick was more specific in identification of significant proteinuria.  Conclusions: We conclude that test dipstick correlates better with 24 hour urine protein estimation than with the protein/creatinine ratio. Further, 1 + urine dipstick could be a good screening tool for identifying proteinuria in patients attending the obstetrics outpatient service. However, the 2 + level on the urine dipstick would be required to serve as be an alternative to the 24-hour urine collection for detection of significant proteinuria or calculation of spot urine P/C ratio.