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Performance of a reagent strip device for quantitation of the urine albumin: creatinine ratio in a point of care setting.

AIM: We have evaluated the performance of a reagent strip (Clinitek, Bayer plc, Newbury) incorporating a novel dip and read device for the quantitation of the albumin: creatinine ratio together with their individual concentrations in urine. METHODS: The performance was compared with that of a lateral flow device for the semi-quantitation of albumin (Micral II, Roche Diagnostics, Lewes) and also a laboratory based procedure. The device employs novel methods for both analytes, using a sulphonephthalein dye binding at pH 1.5 for albumin and the peroxidase-like activity of copper creatinine complexes. The color yields of the separate reaction pads are monitored with the Clinitek 50TM bench top urine chemistry analyzer and compared to a pre-programmed calibration algorithm. RESULTS: The imprecision of the device was assessed by observing the discrepancy between duplicates in a total of 144 urine samples collected from patients with diabetes and/or renal disease; there were 10 discrepancies in the case of the albumin estimation (6.9%), 12 in the case of the creatinine estimation (12.5%) and 23 in the case of the albumin: creatinine ratio (16.0%). In the case of the Micral II, where 96 of the urines were analyzed there were 12 discrepancies (12.5%). When considered as a two-class test for albumin with a cut off of 20 mg/L the Clinitek gave a sensitivity of 95.4% with specificity of 78.9% and a positive predictive value of 87.4%. When analyzing four urines (two controls, two patient pools) with replicate analysis on the Clinitek system we found 100% agreement for the albumin estimation, 95% for creatinine and 96.7% for the albumin: creatinine for 60 analysis within a day and 100, 95 and 97.5% on single analyses each day for 20 days for the two urine controls. The discrepant results were always within one color block. When considering the albumin: creatinine ratio with a cut off of < 30 mg/g the Clinitek gave a sensitivity of 76.3% with a specificity of 89.1% and a positive predictive value of 89.7%. CONCLUSION: The Clinitek system provides a reliable means to screen for microalbuminuria with the opportunity of a semi-quantitative assessment when microalbuminuria is found.

Albuminuria↗

Evaluation of reagent strips in urine tests for detection of Schistosoma haematobium infection: a comparative study in Ghana and Zambia.

The presence of haematuria and proteinuria, detected by reagent strips, was compared with Schistosoma haematobium egg counts in the urines of human subjects from two epidemiologically distinct areas in Ghana and Zambia. In children and adults in both areas, the individual or combined semiquantitative levels of proteinuria and haematuria were related directly to increasing urinary egg counts. In both areas the presence of blood in the urine was highly specific (greater than 85%) and sensitive, being positive in 97% of urine specimens with more than 64 eggs per 5-ml sample of urine. The sensitivity of the protein indicator was also high, but its specificity was less than the blood indicator. The specificity of combined proteinuria and haematuria was higher than either alone; on the other hand, the sensitivity was lower than either alone. At each level of proteinuria and haematuria, the geometric mean urinary egg count was higher in Ghana than in Zambia. This study confirms the necessity to evaluate indirect diagnostic techniques in each endemic country, in order to establish criteria for their interpretation, before wide-scale use.

Adolescent↗

Evaluation of an improved Reagent Strip system for measuring blood glucose.

Using a new, synthetic whole-blood control and an improved reflectance meter, the within-run precision of Dextrostix Reagent Strips for quantitative determination of blood-glucose levels is compared with three common manual methods (hexokinase, o-toluidine, and glucose oxidase), and one automated method (neocuproine-AutoAnalyzer). In addition, the strip is compared on a day-to-day basis with the o-toluidine method. Dextrostix, used with the new instrument and control, provides results that compare very well with the other methods for within-run precision, and with the o-toluidine method for day-to-day results.

Blood Glucose↗

Measurement of the enzymes lactate dehydrogenase and creatine kinase using reflectance spectroscopy and reagent strips.

Two new methods for the assay of total activities of lactate dehydrogenase and creatine kinase are described, in which the enzyme activities are measured from a solid-state reagent strip during a kinetic reaction, the reaction being monitored in the ultra-violet region of the spectrum by reflectance spectroscopy. The performances of these methods are evaluated, and compared to conventional "wet" chemistry methods. The solid-phase reagent methods demonstrated precision and accuracy acceptable for diagnostic purposes, and were easy to use by trained operators.

Clinical Enzyme Tests↗

A dry-reagent strip for quantifying carbamazepine evaluated.

We examined a new colorimetric homogeneous immunoassay for carbamazepine based on the apoenzyme reactivation immunoassay system (ARIS) principle. The test, in dry-reagent strip format, is to be used with the Ames Seralyzer reflectance photometer. Within-run CVs (n = 20) were 3.0%, 2.7%, and 2.8% at 3.0, 6.1, and 12.1 mg/L; between-run CVs (n = 15, in 15 days) were 4.1%, 2.7%, and 1.9% at 6.0, 9.1, and 12.1 mg/L. Mean analytical recovery was 99.9 (SD 2.3)%. Results by this test (y) for clinical plasma specimens (n = 96) compared very well with those obtained by fluorescence polarization immunoassay (y = 1.01 x - 0.02, r = 0.995) and by liquid chromatography (y = 0.99 x + 0.14, r = 0.990). Bilirubin (45 mg/L), uric acid (145 mg/L), and various anticoagulants at about fourfold the usual concentrations did not interfere. High concentrations of cholesterol (4.9 g/L), triglycerides (3.8 g/L), and hemoglobin (4 g/L) caused slight positive interference. Carbamazepine-10,11-epoxide cross reacted only at greater than or equal to 5 mg/L. The two-point calibration line was validly stored for at least three weeks. Free carbamazepine also can be measured. The test is convenient and rapid (test time 80 s), and thus is particularly useful in all clinical settings where prompt testing is needed.

Adolescent↗

Performance evaluation of reflectance meter for glucose determination by two different reagent strips.

Serum glucose concentrations of 112 blood samples determined by the GOD/POD/Trinder method were compared with values obtained on whole blood by means of the Glucometer reflectance meter and two different reagent strips, Dextrostix and an experimental strip (GX 947822), in order to establish over a wide range of glucose concentrations, the precision and reproducibility of reflectometric methods. The two methods examined showed an excellent correlation with the reference method, particularly if data were corrected for the individual hematocrit value, and both accuracy and precision were reasonably satisfactory.

Blood Glucose↗

Diagnostic value of two reagent strips (Multistix 8 SG and Combur 2 LN) in cirrhotic patients with spontaneous bacterial peritonitis and symptomatic bacterascites.

OBJECTIVE: Spontaneous bacterial peritonitis is a life-threatening complication in patients with liver cirrhosis requiring a rapid diagnosis. We have tested two reagent strips, Multistix 8 SG and Combur 2 LN for bedside diagnosis of spontaneous bacterial peritonitis and symptomatic bacterascites, a variant of spontaneous bacterial peritonitis. METHODS: Responses of the two strips in colorimetric scale were compared with results given by cyto-bacteriological analysis of ascitic fluid. Results with positivity in grades 1 and 2 of colorimetric scale were analyzed. RESULTS: Four hundred and forty three paracentesis were performed in 116 patients including 46 samples of ascitic fluid with spontaneous bacterial peritonitis occurring in 25 patients and 20 samples of ascitic fluid with symptomatic bacterascites occurring in 17 patients. Forty two percent of spontaneous bacterial peritonitis were culture-negative neutrocytic ascites, gram-positive pathogens and enterobacteriaceae were responsible for 36% and 21% episodes of spontaneous bacterial peritonitis and 71% and 29% episodes of symptomatic bacterascites respectively. Fifty seven percent of spontaneous bacterial peritonitis had polymorphonuclear cell count<1000/mm3. For spontaneous bacterial peritonitis diagnosis, grade 1 positive Multistix and Combur tests had a sensitivity of 69.6% and 80.4% respectively, and a negative predictive value of 96% and 97.3%. Grade 2 positivity increased specificity to 98% and 99.2% and positive predictive value to 75% and 91% for the two strips respectively. Grade 1 positive tests had a sensitivity of 100% and 90% and a negative predictive value of 100% and 99.4% respectively for diagnosis of spontaneous bacterial peritonitis with polymorphonuclear count > 1000/mm3. For symptomatic bacterascites diagnosis, grade 1 positive tests had a sensitivity of 22.4% and 44.4% respectively and a negative predictive value of 96% and 97%. CONCLUSION: Although Combur had a higher sensitivity than Multistix for the diagnosis of spontaneous bacterial peritonitis, sensitivity of the two strips remains low with polymorphonuclear cell count<1000/mm3. Grade 2 positive Combur test had an acceptable positive predictive value. Sensitivity of both strips is insufficient for diagnosis of symptomatic bacterascites. Rapid cyto-bacteriological analysis of ascitic fluid remains necessary for diagnosis of these complications.

Ascites↗

Guidelines on the use of blood glucose meters and nonmeter blood glucose reagent strips in hospitals. Committee on Monitoring Devices, Canadian Association of Pathologists.

A cross-sectional survey of Canadian hospitals carried out in 1984 revealed a large diversity of practices in the use of blood glucose meters and nonmeter blood glucose reagent strips and of providers of this service. Most hospitals lacked guidelines and acceptable delegation of quality control. The results prompted the Committee on Monitoring Devices of the Canadian Association of Pathologists, composed of representatives of the medical profession, professional organizations, industry and an accrediting organization, to develop guidelines on the use of blood glucose monitoring devices in hospitals.

Blood Glucose↗

A comparison of enzyme reagent strip tests for lacrimal glucose.

Lacrimal glucose screening for diabetes mellitus is becoming increasingly popular in optometric practice. Several commercial glucose test kits are available and can be used for this purpose. This paper compares the cost, reaction range, and reaction time reported for six different types of reagent strip tests.

Costs and Cost Analysis↗

Rapid identification of bacterially contaminated platelets using reagent strips: glucose and pH analysis as markers of bacterial metabolism.

BACKGROUND: One in every 1000 units of platelets is bacterially contaminated, which puts patients at risk for transfusion-associated sepsis and death. However, there is currently no screening test in place to detect contaminated units. The use of commercially available multiple-reagent urine dipsticks for this purpose was evaluated. STUDY DESIGN AND METHODS: Platelet concentrates were inoculated with either sterile saline or suspensions of Staphylococcus aureus, Staphylococcus epidermidis, Bacillus cereus, Klebsiella pneumoniae, or Serratia marcescens to a final concentration of 50 colony-forming units (CFU) per mL. The platelets were analyzed daily by the use of multiple-reagent strips, quantitative culture, and glucometry. RESULTS: B cereus grew rapidly, reaching 10(7) CFU per mL 1 day after inoculation, while S. epidermidis grew slowly, achieving similar concentration 4 to 6 days after inoculation. Two of 10 dipstick reagents, glucose and pH, proved useful in detecting bacteria. Both were lower in bacterially contaminated units than in controls. Glucose data obtained from automated analyzers validated the dipstick data. All organisms were detected at concentrations > or = 10(7) CFU per mL, and S. aureus and K. pneumoniae were detected in the range of 10(3) to 10(5) CFU per mL. CONCLUSION: The multiple-reagent test used had a sensitivity and specificity of 95 percent (> or = 10(7) CFU/mL) and 98 to 100 percent, respectively. These data indicate that urine dipsticks can be used to rapidly and inexpensively detect bacterial contamination in platelet concentrates, which potentially will reduce morbidity and mortality at minimal cost.

Bacillus cereus↗

Capillary blood beta-hydroxybutyrate measurement by reagent strip in diagnosing diabetic ketoacidosis.

OBJECTIVE: To compare blood beta-hydroxybutyrate (beta-OHB) levels measured by reagent strip with serum ketone levels assessed by the nitroprusside reaction in diagnosing diabetic ketoacidosis (DKA). DESIGN: Prospective study of DKA in 19 Thai diabetic patients from September 2001 until August 2002. SETTING: A university hospital. PATIENTS: Nineteen patients with DKA and ten patients with metabolic acidosis from other causes. INTERVENTIONS: Capillary blood alpha-OHB was measured by a blood ketone meter (MediSense Optium). Concurrently, serum ketone was measured semiquantitatively by nitroprusside reaction (Ketostix, N-multistix, and Labstix). MAIN OUTCOME MEASURE: Sensitivity, specificity, and ROC curve of both methods in diagnosing DKA. RESULT: Mean age +/- SD of DKA patients was 45.6 +/- 16.95 years. Plasma glucose was 675.25 +/- 188.15 mg/dL, arterial blood pH 7.19 +/- 0.12, anion gap and serum bicarbonate 29.93 +/- 4.90 and 8 +/- 3.35 mmol/L. Serum ketone was moderately to markedly positive in most cases. Capillary beta-OHB ranged from 2.4 to >6 mmol/L. The sensitivity and specificity of serum ketone by nitroprusside reaction in diagnosing DKA were 95% and 100%. The sensitivity and specificity of capillary beta-OHB was 90% and 100% respectively. The areas under ROC curves of serum ketone and capillary beta-OHB were 0.975 and 0.950 (NS) respectively. CONCLUSION: Serum ketone and blood beta-OHB measurement are equally effective in diagnosing DKA among uncomplicated cases.

3-Hydroxybutyric Acid↗

Evaluation of reagent strips for the rapid diagnosis of nitrite poisoning.

Two commercial urine test strips based on the Griess nitrite-specific diazonium salt reaction, having sulfanilamide and para-arsanilic acid as substrates, respectively, were studied as qualitative tests in the rapid diagnosis of nitrite/nitrate poisoning. Their usefulness was compared to other rapid tests, such as the sulfanilic acid-1 naphthylamin and diphenylamine blue tests. The practical sensitivity limit to nitrites in plasma and in water of both the reagent strips and SA-1NA test was 0.50 micrograms NO2/mL, while the diphenylamine test, which is not nitrite specific, showed a positive reaction to nitrites in plasma and in water above 50 micrograms NO2/mL and 5 micrograms NO2/mL, respectively. The in vitro assays were evaluated in vivo by the sublethal intoxication of a sheep with nitrite, demonstrating that commercial urine test strips may be useful for the rapid diagnosis of nitrite/nitrate poisoning.

Evaluation Studies as Topic↗

Centrifugation techniques and reagent strips in the assessment of microhaematuria.

During a survey for bladder cancer in a healthy male population a surprisingly high incidence of significant microhaematuria was found and no urinary sample was completely free of blood. A study of the sensitivity of the different techniques for assessing microhaematuria seemed necessary. A semiquantitative centrifugation technique, developed for cytological purposes, was found to be the most sensitive. Blood could be detected in concentrations of less than 50 RBC/ml urine. With conventional analysis, performed carefully, the minimum detectable concentration was about 500 RBC/ml. Reagent strips, based on the orthotholidin peroxidase reaction and developed specifically for urine analysis, gave positive reactions in minimum concentrations of 1 000 000 RBC/ml (original Hemastix), 50 000 RBC/ml (new Hemastix), and 20 000 RBC/ml (Sangur-Test). Positive scores with lower concentrations could be obtained with the Sangur-Test strip when it was read with a magnifying glass. However, the degree of erythrocyturia that may be regarded as physiological and that which is pathological has yet to be defined.

Aged↗

[Diagnosis of spontaneous ascites infection in patients with cirrhosis: reagent strips].

AIM: To evaluate the sensitivity, specificity, and predictive values of dipstick testing (DT) for detecting spontaneous bacterial peritonitis (SBP), defined by an ascites neutrophil polymorphonuclear cell count > or = 250/mm3, in patients with cirrhosis. METHODS: The study includes all patients with cirrhosis and ascites admitted to our general hospital on the southern outskirts of the Paris metropolitan area (France) from June 2003 to May 2004 (n = 47:27 men and 20 women). Diagnostic abdominal paracentesis was performed on admission, and a Multistix SG (Bayer Pharma) reagent strip was immersed in one ascitic sample from each patient. Readings after 120 s were either negative (DT-) or positive (DT+, with 4 levels of positivity: trace, +, ++, or +++). In case of cytologically-proven SBP, patients were treated with cefotaxime, and subsequent paracentesis with DT and cytologic testing took place every 48 hours, until recovery. RESULTS: Six of the 47 patients had proven SBP, all with clinical signs of SBP (fever and/or abdominal pain); five of these patients were DT+ and one was DT-. In the five patients initially DT+, the DT became negative at the same time as the cytologic criteria for SBP disappeared. Forty-one patients did not meet the cytologic criteria for SBP: 34 were DT- and 7 were DT+ (traces: 4, ++: 2, +++:1); two of these had clinical signs suggestive of SBP. CONCLUSION: Although the sensitivity (83%), specificity (83%) and negative predictive value (97%) of DTwere satisfactory, its positive predictive value (42%) was low. Dipstick testing of ascitic fluid is easy to perform and inexpensive and may be recommended for diagnosis and follow-up of SBP, especially in emergency settings.

Aged↗

What do the needles, syringes, lancets and reagent strips of diabetic patients become in the absence of a common attitude? About 1070 questionnaires in diabetic clinics.

The aim was to investigate the fate of injection and monitoring material after its use by diabetic patients in different countries (France, Belgium, Luxemburg, Switzeland and Tunisia). Some suitable containers are available for disposal but little is known about the attitudes of patients and physicians to them. 1 070 questionnaires were completed by patients (age: 50 +/- 18 years; diabetes duration: 15 +/- 11 years; 2.8 +/- 1.1 injections per day) visiting 109 doctors. Injections were done at home (72.6%), or both at home and at work (26.6%). At home: needles, syringes, lancets and reagent strips were thrown directly into the bin in 46.9%, 49.9%, 52.2% and 67.6% of cases, respectively; and in a closed plastic bottle in 29. 6%, 28.5%, 28.9% and 19.9% of cases, respectively. Specific containers were used in 8.6% and 6.3% of cases for needles and syringes, respectively. 62% of the bottles and containers were thrown directly into the bin, whereas 15.5% were returned to a pharmacy (4.5% taken to hospitals, 2.9% were burned). At work: 63% of the patients brought their needles and syringes home for disposal, 6.9% kept suitable containers at work and 30% threw their materials directly into local bins. We conclude that awareness should be increased and the organization of the collection of used material improved.

Adult↗

Comparative study of the efficacy of seven paper-reagent strips and conventional biochemical tests in identifying gram-negative organisms.

Gram-nagative organisms were tested with commercially available reagentimpregnated strips (PATHO-TEC). Of the 291 strains, all were tested by using seven paper tests and their conventional counterparts. Excellent correlation was obtained with the oxidase, phenylalanine-deaminase, and Voges-Proskauer tests. Indole tests made on liquid medium cultures also gave complete correlation, but some false-negative results with indole-positive Proteus strains were obtained when growth from solid medium was tested by the strip method. Paper strip urease tests were positive within 2 hr with all Klebsiella and some Serratia, Herellea, and Citrobacter strains as well as with Proteus strains. Approximately 15% of citrate strip test results differed from those of the conventional tests, and reproducibility was poor on retest. The lysine decarboxylase strip test showed a number of discrepancies and posed problems of interpretation and readability. Paper reagent strip methods are simple and convenient and merit further development to increase the specificity of those which depend on pH change up to that achieved with the Voges-Proskauer, oxidase, phenylalanine, and indole methods.

Acinetobacter↗

Haematuria and proteinuria during Schistosoma haematobium infection: relationship to intensity of infection and the value of chemical reagent strips for pre- and post-treatment diagnosis.

The relationship of haematuria and proteinuria to intensity of Schistosoma haematobium infection, the possibility of using haematuria and proteinuria for diagnosing S. haematobium infection, and the value of haematuria and proteinuria in assessing chemotherapeutic efficacy after treatment with praziquantel were studied in 235 male and female schoolchildren, 9-to 14-year old. A correlation was found between both severity of dipstick proteinuria/haematuria and frequency of visible haematuria, and intensity of S. haematobium infection. Haematuria and proteinuria proved reasonably sensitive indicators of urinary schistosomiasis (78% and 86% respectively) and both techniques detected all heavy infections (over 64 eggs/10 ml urine), but haematuria was considered the overall better indicator due to its greater specificity before (83% vs 64%) and after (78% vs 67%) treatment. The presence of visible haematuria detected 19% of all infected children and two-thirds of those passing more than 64 eggs/10 ml urine, and can provide a useful saving of time and the use of reagent strips. Comparison of the results with those obtained elsewhere confirmed regional differences in the intensity of infection inducing specific levels of haematuria/proteinuria and in the sensitivity and specificity of urinary blood and protein as indicators of infection.

Adolescent↗

Recognition of impending ketoacidosis delayed by ketone reagent strip failure.

During a one-year period, six patients were admitted to the hospital in diabetic ketoacidosis following 12 to 24 hours of illness at home. Urine testing with strips impregnated with sodium nitroprusside had indicated that no ketone bodies were present. Nine of 11 bottles of reagent strips in use for less than three months by these and other patients contained totally unreactive strips. Nitroprusside tablets exposed more than three months continued to give accurate readings.

Diabetic Ketoacidosis↗