Assessment of a new visual blood glucose strip.

A new double-tipped strip for home glucose monitoring without a meter is described. Comparison between values obtained with the new method by trained nursing staff and those obtained with a glucose-oxidase analyzer demonstrates close correlation between the two methods (r = +0.95, a = +22.2 mg/dl, b = +1.14). The mean concentration in 117 strip tests over an analyzer range of 5-775 mg/dl (0.3-43.0 mmol/L) was 52 mg/dl (2.9 mmol/L) greater than the analyzer estimate. Forty-seven percent of samples were read as the color block closest to the analyzer estimate. Samples in the lower glucose range tended to read one block high. The technique is faster to perform than most other visual blood glucose strip methods, and is a useful addition to the equipment available for home glucose monitoring. Modifications to the strip by the manufacturers appear to have overcome the low value over-reading error.

Application of reflectance spectroscopy to the estimation of uric acid, urea and glucose: an evaluation of the Ames Seralyzer.

An original approach to the measurement of analytes in clinical chemistry has now become available, in which dry reagent strip technology is linked to measurement by reflectance spectroscopy. The present studies have evaluated the performance of the first of these test systems-for uric acid, urea and glucose, in serum-by comparison with conventional liquid chemistry methods. Satisfactory performance in terms of both precision and accuracy was obtained for all three test systems, the current "state-of-the-art" performance criteria being met; the Seralyzer system proved reliable and easy to use in the hands of trained operators. It should find a place as a "Stat" analyser in the laboratory, in specified wards and in Health Centres.

Measurement of bilirubin, cholesterol and creatinine in serum and plasma, by solid-phase reflectance spectroscopy.

The Seralyzer chemistries for total bilirubin, cholesterol, and creatinine have been examined in the routine hospital laboratory, and have demonstrated good correlation and precision when compared to established routine methodologies. The system has proved to be reliable and easy to use.

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.

Urine specific gravity measurements: comparison of a new reagent strip method with existing methodologies, as applied to the water concentration/dilution tests.

A study was carried out to compare a new, unique chemical strip test for the measurement of urine specific gravity with the traditional methods of hydrometry and refractometry, during water concentration/dilution tests in 12 normal subjects. The pattern of specific gravity results during these serial measurements was virtually identical for the strip and for the comparative methods. Comparison of the strip results with those obtained by both hydrometry and refractometry produced acceptable linear regression data. In addition, a close relationship was demonstrated between the strip specific gravity and urine osmolality. The findings show that the strip method is an acceptable alternative to traditional methods as an indicator of urine concentration.

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.

Selection of sputum specimens for microbiological examination.

The purpose of this study was to compare the leucocyte esterase (LE) strip test with direct microscopy of Gram-stained sputum smears for the demonstration of leucocytes (WBC) and to develop a simple method for selecting specimens suitable for cultural examination. A total of 11% of specimens were demonstrated to be unsuitable for bacteriological examination using the proposed algorithm. It is thought that this technique offers a simple alternative to traditional microscopy alone for screening sputum specimens.

Dextrostix-Eyetone in the insulin hypoglycaemia test.

The Ames Dextrostix-Eyetone system was evaluated for monitoring the blood glucose concentration during insulin-induced hypoglycaemia. The results agreed well with laboratory values for plasma glucose, obtained by an orthotoluidine method, and the method was practicable as a bedside technique. In two cases quick results obtained with the Eyetone enabled the insulin tolerance test to be interrupted to prevent severe hypoglycaemia before the clinical indications were obvious. The extra time and effort required were minimal, and its value seems to far outweigh the disadvantage of the extra work entailed. Nevertheless, care in using the system was important, and the operator must familiarise himself with the system before the most reliable results can be obtained.

Application of substrate-labelled fluorescent immunoassay to the measurement of anticonvulsant and antiasthmatic drug levels in plasma and serum.

The use of the Ames homogeneous Substrate-Labelled Fluorescent Immunoassay is described here. It performed easily and accurately across the therapeutic and low toxic ranges with the drugs phenytoin, phenobarbital, primidone, carbamazepine, and theophylline, and also at high toxic levels subsequent to prior sample dilution. The assay performed well in comparison to the standard assays of gas-liquid chromatography, radioimmunoassay, and enzyme immunoassay, and showed no problems with lipaemic, icteric, or, particularly, uraemic specimens.

An aid to the early detection and management of diabetic nephropathy: assessment of a new point of care microalbuminuria system in the diabetic clinic.

AIMS: To compare the performance of the DCA2000 microalbuminuria system for albumin and creatinine concentrations and the albumin:creatinine ratio (ACR) with laboratory measurements in the hospital diabetes clinic and to assess the ease of use and applicability by standard clinic personnel. METHODS: Urine albumin and creatinine concentration and ACR were measured in 154 diabetic patient samples and in 77 normal subjects. Both albumin assays are based on immunoturbidimetry. The DCA2000 system utilizes reagent cartridges processed automatically. RESULTS: Control material within-run precision (coefficient of variation (CV)) for albumin and creatinine ranged up to 7.1% and 3.3% respectively. Between-run CVs ranged from 2.1% to 4.3%. Method comparisons yielded correlation coefficients > 0.99 for albumin, creatinine and ACR, only a small negative bias of 3.2 mg/l for albumin and 0.10 mg/mmol for ACR, no concentration-related bias for ACR and no between-method difference for either albumin (P = 0.195) or ACR (P = 0.341). At a laboratory albumin concentration cut-off of 20 mg/l the sensitivity, specificity, negative and positive predictive values were 92.4% 100% 92.7% and 100%. Normal reference range mean albumin, creatinine and ACR values for the DCA2000 and the laboratory were 7.7 mg/l vs. 9.0 mg/l 13.0 mmol/l vs. 12.6 mmol/l and 0.66 mg/mmol vs. 0.81 mg/mmol respectively. Clinic personnel found that the DCA2000 system was easy to use suited the clinic environment and generated confidence in the results. CONCLUSIONS: This point of care system safely substitutes laboratory-based measurements. Ease of use and low cost make it suitable for screening and monitoring diabetes treatment. It facilitates the use of random urines, and may obviate the need for timed samples. This approach has a clear place in the battle to reduce the diabetic vascular disease burden.

Microbumintest and non-albumin proteinuria in diabetes.

Bedside methods for the detection of microalbuminuria such as Microbumintest (TM) have the advantage of simplicity but not the specificity of radio-immunoassay. In the present study we assessed whether apparently inappropriate positive Microbumintest results in the presence of low urinary albumin concentrations could be accounted for by non-albumin proteinuria of glomerular or renal tubular origin. Urinary albumin and transferrin were considered to indicate glomerular proteinuria, and alpha-1-microglobulin and N-acetyl-beta-D-glucosaminidase to reflect tubular proteinuria. Microbumintest had a sensitivity of 100% and specificity of 67% to detect a urinary albumin concentration of 40 mg/l. Samples with albumin concentration less than 40 mg/l contained more total protein: 110 (78-155) v 60 (35-104) mg/l p less than 0.0001 (geometric means with 1 SD range), more albumin: 11.7 (5.1-26.8) v 5.4 (2.8-10.4) mg/l p less than 0.005 and more transferrin: 496 (191-1284) v 174 (78-389) micrograms/l p less than 0.001, in those testing positive with Microbumintest than in those testing negative. Microbumintest had a sensitivity of 82% and specificity of 75% to detect an albumin concentration of 20 mg/l. In samples containing less than or equal to 20 mg/l albumin, the mean albumin concentration was no greater in those testing positive compared with those testing negative. However, total protein: 108 (72-161) v 60 (34-105) mg/l p less than 0.001, and transferrin: 326 (148-715) v 157 (78-316) micrograms/l p = 0.01 both remained increased in samples testing positive compared with those testing negative.(ABSTRACT TRUNCATED AT 250 WORDS)