Multistix 10SG Research Articles

Utility of urine dipstick in predicting urinary tract infection in pediatric outpatients

Objectives: Children are most frequently affected by urinary tract infections (UTIs). Urine dipsticks along with use in urine routine testing can help in predicting UTI. In this study we aim to evaluate the utility of individual and combination of urine dipstick parameters, including nitrite and leukocyte esterase (LE), against gold standard urine culture for detection of UTI among pediatric outpatients. Materials and Methods: Nine hundred and forty-nine pediatric urine samples from January 2021 to December 2021 were cultured on Cysteine Lactose Electrolyte Deficient Agar and incubated at 37°C overnight. Siemens Multistix 10SG strips were used to perform a urine dipstick for urine markers. Results from the urine dipstick and culture were contrasted. Statistical Analysis: Data obtained in the study was analyzed statistically using stata version 15. Diagnostic performance of urine dipstick parameters was assessed taking urine culture as gold standard. Receiver operating characteristics (ROC) curve was plotted. Results: About 153 of the 949 urine samples received for culture were positive. Males comprised 102 of the 153 positive patients. The most common organism isolated was Escherichia coli, followed by Klebsiella, Pseudomonas, and Proteus. LE, nitrite, red blood cells (RBC), and protein had a sensitivity of 77.1%, 64.7%, 45.1%, and 46.4%, respectively, whereas their specificities were 94.5%, 97.2%, 95.9%, and 93.1%, respectively. When taken together, “LE and Nitrite and RBC and Protein” had a lower area under the curve (AUC) of 0.641, whereas “LE/Nitrite/RBC/Protein” had the highest AUC of 0.914. Conclusions: The urine dipstick test may be utilized as a screening tool and a positive predictor for UTI. When evaluated simultaneously, nitrite and LE can be used as point-of-care tests preceding the culture examination for decision-making. They can aid in the optimized management of children by minimizing UTI-related complications and inappropriate antibiotic use.

B-037 Comparison of Performance between Siemens Clinitek + Status Analyzer to ARKRAY AUTION MAX AX-4030 for Suspected Urinary Tract Infections

Abstract Background The purpose of the study is to evaluate the performance and agreement of the rapid point-of-care (POCT) urine dipstick testing in the emergency department (ED) to a laboratory-automated platform. Methods A total of 30 urine specimens were collected from the emergency department at our hospital and were simultaneously tested for urinalysis (UA) on the POCT Siemens Clinitek Status+ analyzer using the Multistix 10SG strip. In the laboratory, we performed the tests on the automated ARKRAY Aution MAXTM instrument, using the Aution Sticks 9EB strips. Samples with more than a trace of leukocyte esterase and/or nitrates are considered positive for a urinalysis and further, the samples were reflexed to urine culture. The performance of both platforms was analyzed using EP Evaluator (Data Innovations LLC.). Results A total of 30 urine specimens were analyzed for UA using both the POCT and automated laboratory analyzers. The agreement (95% CI) between leukocyte esterase, nitrites, and blood are as follows: 53.3% (36.1 to 69.8%); 96.7% (83.3 to 99.4%), and 70.0% (52.1 to 83.3%) (see Table 1). Furthermore, out of the 30 specimens that were tested on both platforms, there was prominent discordance between the POCT and lab UA test. The 7 urine samples that were negative on POCT were positive on the laboratory UA platform. All 7 were sent for urine culture, out of 7 only 1 sample was positive for culture which was abnormal: >100 000 CFU/ml Escherichia coli. Out of 30 urine samples specimens that were tested on both platforms, 23 urine samples were in concordance with both platforms out of which 8 urine samples tested positive for culture (5 were E. coli, 1 was E. coli combined with Klebsiella pneumoniae, 1 was solely Klebsiella pneumoniae, 1 was Staphylococcus saprophyticus, and 1 was Streptococcus agalactiae). The remaining 15 urine samples resulted in no significant growth of bacteria or suggesting contamination. The sensitivity of POCT UA and laboratory-performed UA was 89% and 100% respectively. Furthermore, the specificity of POCT UA and laboratory-performed UA was 36% and 7% respectively. Conclusion Our data shows although POCT UA is rapid, a prominent disparity is observed between the POCT UA and automated lab testing. The lab-performed UA has greater sensitivity and specificity compared to the POCT UA. Clinicians should interpret the urine dipstick test results in a clinical context that includes the patient’s history and symptoms, especially when using POCT in the ED.

Efficacy of Ascitic Fluid Dipstick Leukocyte Esterase Activity in Early Diagnosis of Spontaneous Bacterial Peritonitis

Introduction: Spontaneously occurring ascitic fluid infections {Spontaneous Bacterial Peritonitis (SBP)} are the most common and recurring complications in patients with decompensated cirrhosis with ascitis. Unlike other infections, ascitic fluid infections usually present with non specific symptoms and may be asymptomatic in a large number of patients. They not only accelerate hepatic decompensation, but may also lead to, or exacerbate other complications like hepatic encephalopathy, hematemesis, renal failure and death. The existing protocol of diagnosis of SBP includes ascitic fluid total and differential leukocyte counts, and ascitic fluid cultures, by inoculating the ascitic fluid in blood culture vials, which are not only cumbersome, but also costly, time consuming and cannot be followed in all patients presenting for outpatient treatment for therapeutic peracentesis. Aim: To evaluate the efficacy of testing ascitic fluid pH, protein and Leucocyte Esterase (LERS) activity, by using Siemens Multistix 10SG Reagent Strips (SMRS) for early screening of patients for SBP. Materials and Methods: The observational study was conducted at SGRR Institute of Medical and Health Sciences Dehradun, Uttarakhand, India, from January 2018 to March 2019. The study included 329 patients with cirrhosis and ascites presenting in either the Outpatient Department (OPD) or Emergency Room for therapeutic paracentesis or with cirrhotic complications were evaluated for SBP using SMRS for ascitic fluid pH, Leukocyte Esterase (LERS) activity and ascitic fluid protein, for early detection of SBP. The standard diagnostic criteria i.e., ascitic fluid Polymorphonuclear Counts (PNM) more than 250 cells/mm3, by Chamber Counting Method or positive ascitic fluid culture after 48 hours incubation were used as gold standard for diagnosis of SBP. Chi-square test was applied to find out significant association between independent and dependent variables. A p-value of <0.05 was considered significant. Results: Among total 329 patients with cirrhotic ascitic, 81 were diagnosed to have SBP. At a cut-off of 2+, SMRS correctly detected SBP in 77/81 patients, was negative in 4/81 patients and falsely positive in 7/248 NSBP patients, thereby having a sensitivity, specificity, Positive Predictive Value (PPV) and Negative Predictive Value (NPV) of 95%, 97.33%, 98.96% and 96.69%. At a cut-off of 3+, SMRS was able to detect SBP in 53/81 patients, and was falsely positive in 1/248 patients, thereby, although decreasing the sensitivity to 64%, but improving the specificity and PPV to 99.6% and 98.11%, respectively. Conclusion: During diagnostic paracentesis, ascitic fluid LERS activity using SMRS are highly sensitive markers for early detection of SBP, especially in the presence of fever, vomiting and shock.

SCREENING STUDY OF DIPSTICK URINALYSIS OF HEALTHY NEONATES DELIVERED IN TERTIARY CARE HOSPITAL, FROM VADODARA, GUJARAT

Background: Urinary dipstick is one of the most important advances in the current diagnostic procedure in pediatric nephrourology. Dipstick test is easy to perform bedside test, gives an immediate result, is relatively cheap, and require less sophisticated training of personnel; so could be used for asymptomatic patients. Objectives: The objectives of the study were to evaluate the usefulness of urine dipstick bedside screening test for diagnosis of underlying congenital kidney disease in otherwise healthy neonates. Materials and Methods: The study was conducted from April 2018 to November 2018. A total of 900 healthy newborns were enrolled. Random spot urine samples were obtained within first 72 h of life. Dipstick test was performed using Siemens Multistix 10SG and positive or negative reading for biochemical parameters was recorded and compared with laboratory test. Newborns with 1st positive dipstick test were issued screen positive cards and called for follow-up on 7th day of life for 2nd dipstick test. Those with persistent 2nd dipstick positive were further investigated to rule out any congenital anomaly. Results: Of total 900 neonates, 504 (56%) were males and 396 (44%) were females. Of the total newborns, 441 (49%) were positive for proteinuria, 2 (0.2%) for nitrites, and 54 (6%) for leukocytes during 1st dipstick urinalysis. Urine routine microscopic evaluation showed 450 (50%) positive for protein and 322 (35%) positive for pus cells. On subsequent follow-up of positive cases, only 2 (0.5%) newborns were positive for proteinuria on 2nd dipstick (p=0.7061). Conclusion: Bedside dipstick urine test as a screening test was not useful in otherwise healthy neonates due to renal immaturity in first few days of life.

Analytical verification of 12 most commonly used urine dipsticks in Croatia: comparability, repeatability and accuracy.

IntroductionVariability among manufacturers of urine dipsticks, respective to their accuracy and measurement range, may lead to diagnostic errors and thus create a serious risk for the patient. Our aims were to determine the level of agreement between 12 most commonly used urine dipsticks in Croatia, examine their accuracy for glucose and total protein and to test their repeatability.Materials and methodsA total of 75 urine samples were used to examine comparability and accuracy of 12 dipstick brands (Combur 10 TestM, ChoiceLine 10, Combur 10 TestUX, ComboStik 10M, ComboStik 11M, CombiScreen 11SYS, CombiScreen 10SL, Combina 13, Combina 11S, Combina 10M, UriGnost 11, Multistix 10SG). Agreement between each dipstick and the reference (Combur 10 TestM) was expressed as kappa coefficient (acceptable κ ≥ 0.80). Accuracy for glucose and total protein was tested by comparison with quantitative measurements on analysers: AU400 (Beckman Coulter, USA), Cobas 6000 c501 (Roche Diagnostics, Germany) and Architect plus c4000 (Abbott, USA). Repeatability was assessed on 20 replicates (acceptable > 90%).ResultsBest agreement was achieved for glucose, total protein and nitrite (11/11, k > 0.80) and the lowest for bilirubin (5/5, k < 0.60). Sensitivities for total protein were 41-75% (AU400) and 56-92% (Cobas and Architect); while specificities were 41-75% (AU400, Cobas, Architect). Dipsticks’ sensitivity and specificity for glucose were 68-98%. Most of the dipsticks showed unacceptable repeatability (6/12, < 90%) for one parameter, most prominently for pH (3/12, < 90%).ConclusionsMost commonly used dipsticks in Croatia showed low level of agreement between each other. Moreover, their repeatability varies among manufacturers and their accuracy for glucose and proteins is poor.

Evaluation of the Sensitivity and Specificity of Use of Glucose and pH for Bacterial Screening of Platelet Concentrates Compared to the Bact/Alert.

Bacterial contamination of blood components is the major infectious risk in transfusion medicine. Since platelets should be stored at room temperature that makes them an excellent growth medium for bacteria; it is mentioned as a major problem in transfusion medicine. Transfusion risk of a bacterial contaminated platelet concentrate is higher than viral pathogen such as HIV, HBV, HCV and HTLV. The objective of this study was to evaluation of the sensitivity and specificity of use of glucose and pH for bacterial screening of platelet concentrates compared to the Bact/Alert. 1332 platelet concentrates were screened by the Bact/Alert system for aerobic and anaerobic bacterial contamination. Bacterial contamination was also evaluated by using urine reagent strips (Multistix10 SG Bayer) and culture methods. Moreover PH screening with a pH meter (Metrohm 744 Swiss) and glucose was also used for detection of bacterial contamination. The rate of bacterial contamination detected by the Bact/Alert system in platelet concentrates was 25 in 1332 (1.9%). It contained 15 (1.1%) for aerobic bacteria and 10 (.8%) for anaerobic bacteria. 226 of 1332 were considered as containing bacteria by using urine reagent strips. Six of the 226 units were also positive by the Bact/Alert system. Three of those units were culture positive for aerobic bacteria and three for anaerobic. The result of platelet concentrates that underwent pH screening by use of pH meter and a pH portion of urine reagent strips was the same. The sensitivity and specificity of considering glucose alone for detection of bacterial contamination were 12 and 98% respectively. For pH alone, these were 24 and 83%. For glucose and/or pH, these were 24 and 83%; and for combination of glucose and pH, these were 12 and 98%. Our results showed use of glucose/pH strips would improve the safety of blood products and should be encouraged.

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Objectives Dipstick urinalysis is widely used for screening of proteinuria in pregnancy. Conflicting results have been reported for diagnostic accuracy between visual and automated methods. We compared semi-quantitative visual and automated dipstick methods with protein:creatinine ratio (PrCr, ⩾30 mg/mmol defined as elevated) in high risk pregnancy. Methods As part of routine clinical care, 517 random midstream urine samples were collected prospectively from consecutive outpatient ( N = 136) and inpatient ( N = 203) pregnant women attending high-risk maternity clinics. Samples were split into two aliquots. The first underwent point-of-care proteinuria testing using visual test strips (Multistix 10SG, Siemens Healthcare Diagnostics, Inc., Tarrytown NY). The second aliquot was sent to the hospital laboratory for analysis by each of two automated dipstick test strips (Multistix 10SG strip, Bayer Clinitek 50; Chemstrip®10 MD, and Urisys 1100®) and PrCr. For PrCr, urinary protein was measured by a pyrogallol red dye-binding method, and creatinine by an enzymatic method. For each of the dipstick methods, positive test thresholds (see Table) were used to determine diagnostic accuracy for PrCr ⩾ 30 mg/mmol. Results Included were 470 (91.7%) urine samples tested by all dipstick methods. The prevalence of proteinuria was low. All dipstick proteinuria methods showed low sensitivity and high specificity for detection of PrCr ⩾ 30 mg/mmol, although visual dipstick urinalysis had lower sensitivity than either automated method. For all dipstick methods, the positive likelihood ratio (LR) was good-excellent, but the negative LR was poor-fair. Conclusions Automated dipstick methods are more sensitive than visual urinalysis for detection of proteinuria, but diagnostic test performance is still poor-fair as a ‘rule-out’ test for proteinuria. Whether the enhanced sensitivity would be worth the cost and training is to be determined. Table 1 . AUC (area under the curve), CI (confidence interval), LR (likelihood ratio). Group 1 Visual Multistix 10SG strip Group 2 Automated Multistix 10 SG, Bayer Clinitek 50 Group 3 Automated Chemstrip® 10 MD, Urisys 1100® Positive test threshold +1 (0.3 g/l) +1 (0.3 g/l) +1 (0.25 g/l) Proteinuria present 36 (7.7%) 83 (17.7%) 59 (12.6%) Sensitivity (%, 95% CI) 50 (38–62) 71 (59–81) 63 (50–74) Specificity (%, 95% CI) 98 (97–99) 91 (87–93) 95 (93–97) Positive LR (95% CI) 40.8 (16.49–100.96) 7.42 (5.30–10.41) 12.83 (8.04–20.49) Negative LR (95% CI) 0.51 (0.40–0.65) 0.32 (0.22–0.47) 0.39 (0.28–0.54) AUC (95% CI) 0.74 (0.66–0.83) 0.81 (0.74–0.88) 0.79 (0.72–0.87) Disclosures M.E. Correa: None. A.C. Halstead: None. A. Cote: None. D.A. De Silva: None. L. Wang: None. P. von Dadelszen: None. L.A. Magee: None.

Rapid diagnosis of spontaneous bacterial peritonitis using leukocyte esterase reagent strips in Emergency Department: Uri-Quick Clini-10SG® vs. Multistix 10SG®

Background and aim. Bacterial peritonitis (SBP) is the most frequent infection in patients with cirrhosis causing significant mortality. Delay in SBP diagnosis is a serious problem. The aim of this study was to evaluate the diagnostic yield of Uri-Quick Clini-10SGR vs. Multistix 10SGR reagent strips in an Emergency Department.Material and methods. A prospective study of consecutive patients with ascites and paracentesis attending to Emergency Department from March 2005 to February 2007 was made. SBP was defined by 250 neutrophiles /mm3. The ascites obtained at bedside was immediately tested in a dry test tube with both the Uri-Quick Clini 10SGR and MultistixSG10R. The Uri-Quick Clini 10SGR and Multistix SG10R. Strips were considered positive at grade. 3 (.125 leukocytes/mL).Results. A total of 223 ascitic fluid samples were obtained. There were 49 episodes of SBP. Median age was 54 (range 18-87 year) years; 62.3% were female. The sensitivity, specificity, PPV, NPV, and 95% CI for Uri-Quick Clini 10SGR were 79.6 (64-87), 98.2 (94-99), 90.5 (78-96) and 93.9 (89-96), respectively. For MultistixSG10R the values were 77.5 (64-88), 97.7 (93-98), 90 (77.9-96.2), and 94 (89.4-96.6), respectively.Conclusion. The use of reagent strip is useful for SBP diagnosis in an emergency setting. The high PPV allow start antibiotic treatment. In areas without the resources to perform conventional ascites fluid analyses, these strips could be presentlyused.

PP025. Urinary dipstick proteinuria testing – Does automated strip analysis offer an advantage over visual testing?

The visual urinary test strip is widely accepted for screening for proteinuria in pregnancy, given the convenience of the method and its low cost. However, test strips are known to lack sensitivity and specificity. The 2010 NICE (National Institute for Health and Clinical Excellence) guidelines for management of pregnancy hypertension have recommended the use of an automated test strip reader to confirm proteinuria (http://nice.org.uk/CG107). Superior diagnostic test performance of an automated (vs. visual) method has been proposed based on reduced subjectivity. To compare the diagnostic test properties of automated vs. visual read urine dipstick testing for detection of a random protein:creatinine ratio (PrCr) of ⩾30mg/mmol. In this prospective cohort study, consecutive inpatients or outpatients (obstetric medicine and high-risk maternity clinics) were evaluated at a tertiary care facility. Random midstream urine samples (obtained as part of normal clinical care) were split into two aliquots. The first underwent a point-of-care testing for proteinuria using both visual (Multistix 10SG, Siemens Healthcare Diagnostics, Inc., Tarrytown NY) and automated (Chemstrip 10A, Roche Diagnostics, Laval QC) test strips, the latter read by an analyser (Urisys 1100®, Roche Diagnostics, Laval QC). The second aliquot was sent to the hospital laboratory for analysis of urinary protein using a pyrocatechol violet molybdate dye-binding method, and urinary creatinine using an enzymatic method, both on an automated analyser (Vitros® 5,1 FS or Vitros® 5600, Ortho-Clinical Diagnostics, Rochester NY); random PrCr ratios were calculated in the laboratory. Following exclusion of dilute samples with urinary creatinine concentration <3mM (given inflation of PrCr values in dilute urine by our method), diagnostic test properties were determined for visual and automated dipstick proteinuria testing (⩾1+) for detection of a random PrCr ⩾30mg/mmol. 160 women (81.9% outpatients) were screened at one/more antenatal visits, providing a total of 233 urine samples for analysis. Both visual and automated read urinary dipstick testing showed low sensitivity (56.0% and 53.9%, respectively). Positive likelihood ratios (LR+) and 95% CI were 15.0 [5.9,37.9] and 24.6 [7.6,79.6], respectively. Negative LR (LR-) were 0.46 [0.29,0.71] and 0.47 [0.31,0.72], respectively. Automated dipstick urinalysis is not more sensitive than visual read urinalysis for detection of proteinuria in a primarily outpatient setting in pregnancy. Both have excellent LR+ but only fair to poor LR- as previously recognised for visual dipstick testing. Performance of automated strip analysis testing may vary with the test strips and analyser used.

A study of the relationship between albuminuria, proteinuria and urinary reagent strips

The aims of this study were to examine the relationship between proteinuria and albuminuria and to assess the equivalence between the albumin to creatinine ratio (ACR) and the protein to creatinine ratio (PCR) at the cut-offs recommended by the National Institute for Health and Clinical Excellence (NICE) guidance on chronic kidney disease. The sensitivity and specificity of the reagent strips used in our laboratory for the detection of clinical proteinuria was also assessed. Urine samples (n = 117) were screened for protein using the Bayer Multistix 10SG and read manually. Urinary total protein and creatinine was measured on the Roche P Modular by the benzethonium chloride and kinetic Jaffe methods, respectively. Urinary albumin was measured by immunoturbidimetry on the Roche Cobas Mira. The relationship between urinary protein and albumin loss was non-linear (P < 0.05). As urinary protein loss increased the percentage of albumin to total protein increased. At the NICE guidance recommended cut-offs for clinical proteinuria (ACR > or =30 mg/mmol and PCR > or =50 mg/mmol) there was one discordant result between ACR and PCR (ACR <30 mg/mmol and PCR >50 mg/mmol). The Bayer Multistix 10SG had a sensitivity and specificity of 97% and 62%, respectively, for the detection of clinical proteinuria compared with ACR. The proportion of urinary total protein attributable to albumin changes with concentration. There was only one discordant result between ACR and PCR: therefore either ratio may be used for the identification of clinical proteinuria. As a screening test for proteinuria, the Bayer Multistix 10SG had an acceptable sensitivity but poor specificity.

Bedside leucocyte esterase reagent strips with spectrophotometric analysis to rapidly exclude spontaneous bacterial peritonitis: a pilot study

Spontaneous bacterial peritonitis, a potentially fatal complication of cirrhotic ascites, is diagnosed when the polymorphonuclear leucocyte count in the ascitic fluid is>250/mm. Manual laboratory counting of ascitic polymorphonuclear leucocytes is, however, labour-intensive, costly, results in diagnostic delay and it is not available in all hospitals as part of the 'out-of-hours' service. Thus, a rapid diagnostic screening test for spontaneous bacterial peritonitis would be beneficial in this condition. An exciting new development in the diagnosis of spontaneous bacterial peritonitis is the use of bedside reagent strips; yet, concerns regarding the inherent subjectivity of result reading have prevented the widespread adoption of this technique in clinical practice. To evaluate the combined use of a leucocyte esterase strip together with an objective portable spectrophotometric reading device in the diagnosis of spontaneous bacterial peritonitis when compared with standard manual laboratory polymorphonuclear leucocyte counting. Nonselected cirrhotic patients undergoing diagnostic paracentesis had an ascitic sample sent for a conventional polymorphonuclear leucocyte count, Gram stain and culture. In addition, a sample was tested with a bedside Multistix 10SG reagent strip and the result was analysed by the Clinitek Status. The strip test was considered positive if it read anything other than negative (i.e. 'trace', '+1', '+2' or '+3'). The sensitivity, specificity, positive predictive value, negative predictive value and accuracy of the reagent strips to diagnose correctly spontaneous bacterial peritonitis when compared with the manual laboratory polymorphonuclear leucocyte count were 100, 91, 50, 100 and 92%, respectively. Bedside leucocyte esterase strips, spectrophotometrically read, can reliably exclude spontaneous bacterial peritonitis in patients with cirrhotic ascites. In our series, a negative strip result effectively ruled out this important condition, and suggests that the requirement for manual polymorphonuclear leucocyte counting in this setting could be removed.

Evaluation of reagent strips for ascitic fluid leukocyte determination: is it a possible alternative for spontaneous bacterial peritonitis rapid diagnosis?

In order to evaluate the accuracy of a urine reagent dipstick (Multistix 10SG) to determine ascitic fluid leukocyte count, we prospectively studied 106 cirrhotic patients from April 2003 to December 2004, in two different centers (Federal University of São Paulo - UNIFESP-EPM and Federal University of Juiz de Fora - HU-UFJF) for the rapid bedside diagnosis of spontaneous bacterial peritonitis. The mean age 54 +/- 12 years, there was a predominance of males (eighty-two patients, 77%), and alcohol was the most frequent etiology (43%). Forty-four percent of patients were classified as Child B and fifty-one as Child C (51%). Abdominal paracentesis was performed both in outpatient and inpatient settings and the Multistix 10SG was tested. Eleven cases of spontaneous bacterial peritonitis were identified by means of polymorphonuclear count. If we considered the positive Multistix 10SG result of 3 or more, the sensitivity, specificity, positive and negative predictive value were respectively 71%, 99%, 91% and 98%. With a positive reagent strip result taken as grade 2 (traces) or more, sensitivity was 86% and specificity was 96% with positive and negative predictive values of 60% and 99%, respectively. Diagnostic accuracy was 95%. We concluded that the use of a urine reagent dipstick (Multistix 10SG) could be considered a quick, easy and cheap method for ascitic fluid cellularity determination in SBP diagnosis.

EFFECT OF RED CELLS, LEUKOCYTES, AND BACTERIA ON URINE DIPSTICK TESTING FOR PROTEIN: ROLE IN THE TRANSIENT ALBUMINURIA OF URINARY TRACT INFECTION.

Urinary tract infection (UTI) may be characterized by transient albuminuria on urinary dipstick testing. The etiology of transient albuminuria in UTI is unclear but may be considered to result from glomerular or nonglomerular sources. We have theorized that nonglomerular sources are the more likely cause and could include infection-associated inflammation of the bladder mucosa with release of serum albumin into the urine and/or represent a false-positive result from red cells (RBCs), leukocytes (WBCs) and/or bacteria (BAC). To test the latter hypothesis, we mixed RBCs (fresh blood draw), WBCs (buffy coat from RBC sample), or BAC (laboratory grade E. coli for standard subcloning studies) with normal urine and performed dipstick testing for albuminuria (DTFA). All cellular fractions were prepared by washing × 3 in PBS and cell numbers determined after counting in a hemocytometer. To assess the effect of temperature, samples were examined at 24°C (room temperature) and after 1 hour at 37°C (similar to physiologic conditions). DTFA was performed using Multistix 10SG dipsticks (Bayer). Results As shown, neither RBCs nor WBCs affected urinary dipstick albuminuria at 24°C, however, BAC gave a positive test. In contrast, at 37°C, all cellular elements gave positive DTFA. Control tubes with PBS were negative for DTFA for all conditions and temperatures. The data suggest that at 37°C, RBCs, WBCs, and BAC may result in positive DTFA in urine and that the temperature may influence the result. It is unclear from these studies if the DTFA represent a false positive (ie, interference with the dipstick) or liberation of albumin from cells. Conclusion The transient albuminuria of UTI may result in part from RBCs, WBCs, and/or BAC giving positive DTFA. We would theorize that with therapy, the urinary concentration of the above cells is reduced, leading to a “clinical resolution” of albuminuria. Additional studies investigating combinations of cellular fractions and/or direct assays for albumin may give further clues to the etiology of this phenomenon.

A Prospective Study of the Impact of Automated Dipstick Urinalysis on the Diagnosis of Preeclampsia

Objective: To determine prospectively in hypertensive pregnant women 1) the accuracy of dipstick testing for proteinuria using automated urinalysis, 2) factors that might affect such accuracy, and 3) the potential impact of automated dipstick testing on the accuracy of diagnosis of preeclampsia according to acceptance of proteinuria at either 1 + or 2 + level. Design: Prospective study. Setting: Antenatal day assessment unit and antenatal ward of St George Hospital, a teaching hospital in Sydney, Australia. Population: 170 hypertensive pregnant women attending as outpatients or inpatients. Methods: 503 midstream urine samples were collected prospectively on separate occasions from 170 women. Full urinalysis was recorded using the Bayer Clinitek 50 automated urinalysis device and Multistix 10SG urinalysis strips (Bayer Diagnostics, Victoria, Australia). Each MSU was analysed for spot protein/creatinine ratio and also for culture and sensitivity if symptoms of a urinary tract infection were present or dipstick included positive nitrites. Urinalysis protein results were compared with spot urinary protein/creatinine ratio (previously shown to correlate with 24‐hr urine protein excretion) to determine the accuracy of urinalysis. True proteinuria was defined as a ratio ≥ 30 mg protein/mmol creatinine. Results: False positive dipstick tests ranged from 7% at 3 + level to 71% at 1 + proteinuria level while false negative rates were 7% for “nil” and 14% for “trace” proteinuria, 9% overall. Accepting the dipstick proteinuria result at face value led to an incorrect diagnosis of preeclampsia or gestational hypertension in 85 (50%) women. Dipstick proteinuria was significantly more likely to be correct (true positive/true negative) if diastolic blood pressure was elevated > 90 mmHg (p = 0.032) and in the absence of ketonuria (p = 0.001). Accepting a diagnosis of preeclampsia on the basis of de novo hypertension and dipstick testing alone was accurate less often (70%) when > 1 + was used as a discriminant value than at the 82% of presentations when > 2 + was used (p = 0.001). Conclusion: Accepting “nil” or “trace” proteinuria as a true negative dipstick results fails to identify approximately 1 in 11 hypertensive pregnant women with true proteinuria, a false negative rate that may be acceptable provided these women are subject to ongoing vigilant clinical review. Even with automated urinalysis the false positive rate for dipstick levels ≥ 1 + is very high, particularly in the presence of ketonuria and relying on this alone to diagnose preeclampsia leads to significant errors in diagnosis. Accepting ≥ 2 + dipstick proteinuria improves overall diagnostic accuracy for preeclampsia at the expense of a higher false negative rate. This study emphasizes the need to confirm dipstick proteinuria with a further test such as a spot urine protein/creatinine ratio in all hypertensive pregnant women, particularly in research studies.

Multisite evaluation of a new dipstick for albumin, protein, and creatinine.

The goal of our study was to perform a multisite evaluation of a new urine dipstick called Multistix PROtrade mark (Bayer, Elkhart, IN), which has reagent pads for the simultaneous assay of urinary albumin, protein, and creatinine. Patients' urine specimens were assayed at four sites with these dipsticks and with the familiar Bayer Multistix 10SG dipsticks for protein. The new dipstick pads for albumin are impregnated with bis (3',3"-diiodo-4',4"-dihydroxy-5',5"-dinitrophenyl)-3,4,5,6-tetrabromo-sulfonephthalein (DIDNTB) dye. These dipsticks also have a novel pad that estimates urinary creatinine using the peroxidase activity of the copper-creatinine complex. We determined the interlaboratory agreement of these dipsticks by comparing dipstick results to values obtained by quantitative analytical methods. We found that dividing the dipsticks' albumin or protein results by the creatinine concentration reduced the number of false-positive albumin or protein values observed in concentrated urines, and reduced the number of false negatives in dilute urines. The ratio of albumin to creatinine, or protein to creatinine gives a better measure of albumin or protein excretion. Compared to reading by eye, the dipstick results agreed better with the quantitative assays when they were read by a reflectometer (Bayer Clinitek).

A comparison between two screening methods for detection of microproteinuria

OBJECTIVE: We compared two screening tests for microproteinuria with 24-hour quantitative measurements to determine which method is better at predicting clinically significant proteinuria. STUDY DESIGN: We obtained 690 24-hour urine collections from both low- and high-risk patients seen for prenatal care. Qualitative screening for microproteinuria on the basis of the protein-error-of-indicators principle (Ames Multistix 10SG and Micro-bumintest, Miles Diagnostic Division, Elkhart, Ind.) was done by the same investigator (C.S.). Quantitative assay was done by use of pyrogallol red-molybdate for total protein and by radioimmunoassay for albumin. RESULTS: The Micro-bumintest had a sensitivity of 87% compared with 36% for the Multistix 10SG. It also had a higher specificity and higher positive and negative predictive values. The Micro-bumintest was a better screening test in patients with significant protein excretion (>300 mg/24 hours). CONCLUSION: The Micro-bumintest has a much higher sensitivity and a lower false-negative rate than does the Multistix 10SG. Our data support the Micro-bumintest as a better screening test for clinically significant proteinuria.

Enhanced Urine Screen Device Predictions

Two urine screen devices were tested to determine whether the predictive use of either or both approached the sensitivity achieved by culture. The Filtra-Check-UTI (FC) urine screen to predict the presence of bacteriuria was compared with the leukocyte and nitrite tests included in the Ames Multistix 10SG (AM) urinalysis dipstick. One thousand eighteen urine specimens (579 collected midstream and 439 collected by catheter) were analyzed. Four hundred twenty-eight urine specimens were culture-positive at the level of 104 or greater colony-forming units (CFUs) per milliliter. The AM dipstick and FC screen showed respective specificities of 85.1% and 81.5% and sensitivities of 68.7% and 80.8%. The AM dipstick correctly predicted 68.7% of positive cultures, and the FC screen correctly predicted 76.6% of positive cultures. However, analysis of the data indicated that when the FC screen was used as a second urine screening device for AM-negative urine specimens, overall positive prediction increased to 85.7% of total culturepositive specimens. The observation of 1+ or greater urine reaction for blood or protein using the AM dipstick indicated the potential failure to absorb into the FC screen, which was termed clogging.