Optimal bedside urinalysis for the detection of proteinuria in hypertensive pregnancy: a study of diagnostic accuracy.

OBJECTIVE: To compare semi-quantitative visual and automated methods of urine testing with fully quantitative point of care urinalysis for the detection of significant proteinuria (0.3 g/24 hours) in pregnancy complicated by hypertension. DESIGN: A prospective comparative study. SETTING: A large teaching maternity hospital. SAMPLE: One hundred and seventy-one pregnant women referred to the obstetric day-care unit for assessment of newly arisen hypertension. METHODS: Early morning urine specimens were tested with four dipstick techniques (Multistix 8SG visual and automated and microalbumin/creatinine ratio visual and automated; Bayer, Elkhart, USA) as well as a fully quantitative measure of the microalbumin creatinine ratio with the DCA 2000 (a point of care assay for albumin; Bayer). These results were compared to a 24-hour urine protein measurement and measures of diagnostic accuracy/prediction are reported. MAIN OUTCOME MEASURES: Significant proteinuria (> or =0.3 g/24 hours) measured by laboratory assay. RESULTS: Automated dipstick urinalysis using the Clinitek 50 has significantly better predictive values for significant proteinuria (LR(+) 4.27, 95% CI 2.78 to 6.56; LR(-) 0.225, 95% CI 0.14 to 0.37) than conventional visual dipstick urinalysis (LR(+) 2.27, 95% CI 1.47 to 3.51; LR(-) 0.635, 95% CI 0.49 to 0.82). Dipstick microalbumin/creatinine ratio testing did not improve overall detection rates with automated or visual testing. Fully quantitative point of care measurement of albumin/creatinine ratio (ACR) was significantly better than any dipstick technique (LR(+) 14.6, 95% CI 6.74 to 31.8; LR(-) 0.069, 95% CI 0.030 to 0.16). CONCLUSIONS: This study confirms that in pregnancy automated dipstick urinalysis is a more accurate screening test for the detection of proteinuria than visual testing. ACR testing can offer a significant improvement over conventional urinalysis if a fully quantitative method of detection is employed that uses pregnancy-specific thresholds. Dipstick assessment of ACR does not improve the detection rate of significant proteinuria.

Patient initiated home blood pressure recordings are accurate in hypertensive pregnant women.

OBJECTIVE: We undertook this study to determine the accuracy and reliability of patient initiated blood pressure measurement and recording. METHODS: We recruited 72 women from the antenatal hypertension clinic in a university teaching hospital. All were at high risk for preeclampsia and were asked to measure and record their blood pressure three times per day at home using a validated blood pressure device with an internal memory. RESULTS: From 979 measurements taken only 28 (2.9% were inaccurate). The inaccurate readings were restricted to three women. On further questioning two women admitted that the device had been used by other family members thus making comparison with the memory impossible. Thus the true nonconcordance rate amongst participants was 1/72 (1.4%). CONCLUSIONS: We conclude that blood pressure recordings taken and documented by high-risk women at home are accurate. This allows more frequent measurements to be taken without the inconvenience of additional visits to hospital and may therefore lead to the earlier detection of preeclampsia.

Neutrophil intracellular pH and Na+/H+ exchanger activity in pre-eclampsia.

Elevated Na(+)/H(+) exchanger activity and intracellular acidosis have previously been demonstrated in white blood cells isolated from women who have suffered from a pre-eclamptic pregnancy. The mechanisms underlying this abnormality and the implications in pre-eclamptic pregnancies are, at present, unclear. In this study, we used neutrophils from third trimester pre-eclamptic patients and third trimester normotensive pregnant controls to determine Na(+)/H(+) exchanger isoform-1 (NHE-1) activity and intracellular pH. This was performed using a well-validated technique involving flurometry and a pH sensitive dye, 2,7'Bis-(carboxyethyl) 5.6 carboxyfluorescein acetomethyl ester (BCECF-AM). Time course experiments were performed to assess the contribution of plasma factors to intracellular pH measurements. Plasma digoxin-like factor (DLF) was assessed in both patients and normotensive controls. Neutrophil intracellular pH was significantly lower in the pre-eclamptic patients (7.15 +/- 0.050) compared with the normotensive pregnant controls (7.36 +/- 0.027; P<.001). NHE-1 activity (in mmol/L/min) was significantly higher in the pre-eclamptics (32.4 +/- 1.9) compared with the normotensive neutrophils (27.1 +/- 1.6; P =.038). Times course experiments showed that mean pre-eclamptic intracellular pH increased from 7.11 +/- 0.049 to 7.25 +/- 0.043 after 2 hours of incubation. DLF, measured as amount of inorganic phosphate liberated from adenosine triphosphate (ATP), was significantly lower when plasma from the pre-eclamptic patients was incubated with the enzyme compared with plasma from the normotensive pregnant women (54.9 +/- 2.6 nmol/mL plasma v 63.91 +/- 1.7 nmol/mL plasma, n = 6, P =.018 unpaired Student's t test). The results suggest that elevated NHE-1 activity and intracellular acidosis are intermediate phenotypes in women who have pre-eclampsia. Intracellular pH may have been affected by plasma as shown in the time course experiments. DLF, an inhibitor of Na(+)/K(+)ATPase, may contribute to this intracellular acidosis in pre-eclamptic neutrophils.