Evaluation of the HemoCue compared with the Coulter STKS for measurement of neonatal haemoglobin

OBJECTIVE

To compare the measurement of haemoglobin concentration ([Hb]) using the HemoCue haemoglobinometer with that using the Coulter STKS haemoglobinometer.

DESIGN

Thirty two EDTA samples were taken from neonates. [Hb] was measured in these samples using the HemoCue; the samples were then transferred to the haematology laboratory for [Hb] determination with the Coulter STKS. In addition, [Hb] was determined in 50 different random EDTA neonatal samples already held in the laboratory, using the HemoCue and Coulter STKS.

PATIENTS

Neonates in the intensive care and low dependency Units of the Royal Devon and Exeter Hospital.

INTERVENTIONS

Samples were collected from arterial lines or by venepuncture or heel prick into an EDTA bottle.

MAIN OUTCOME MEASURES

[Hb] using the HemoCue and Coulter STKS methods.

RESULTS

The mean [Hb] measured using the HemoCue was 150.3 g/l (range 78-215) compared with 152.8 g/l (range 78-217) measured using the Coulter STKS, with a mean of the differences of 2.5 g/l. The standard deviation of the differences of the 82 samples was 3.73 g/l. The limits of agreement of the two methods (mean difference +/- 2SD) were -4.8 to +9.8 g/l.

CONCLUSION

With adequate training and monitoring, the HemoCue can be used directly on the neonatal unit for rapid determination of [Hb] to within 7.5 g/l compared with the laboratory Coulter STKS, using much smaller sample volumes.

[Standard material for measurement of hemoglobin A1c]

In Japan, the standardization of measurement of hemoglobin A1c(HbA1c) has been successfully achieved using the standard material(JDS Lot 1, lyophilized, two levels) produced and distributed by the former Shima Committee of the Japan Diabetes Society(JDS). However, methods for measurement of HbA1c other than the HPLC method, for example immunoassay, have been commonly used in the laboratory. Peptide mapping, a candidate method of analytical chemistry for determination of HbA1c, cannot be applied to a lyophilized sample. The present JDS Committee, which continues the work of the Shima Committee, recently certified a deeply-frozen material as the primary standard reference material(five levels) and named it JDS Lot 2. The Lot 2 value of HbA1c is the same as Lot 1, and is different from the National Glycohemoglobin Standardization Program(NGSP) value by -0.3%. It is likely that the standardization of measurement of HbA1c in the future in Japan will be continued using with JDS Lot 2.

The national glycohemoglobin standardization program: a five-year progress report

BACKGROUND

The Diabetes Control and Complications Trial (DCCT) and the United Kingdom Prospective Diabetes Study (UKPDS) demonstrated conclusively that risks for complications in patients with diabetes are directly related to glycemic control, as measured by glycohemoglobin (GHB). In 1994, one year after the DCCT results were reported, the American Diabetes Association (ADA) set specific diabetes treatment goals. However, 1993 College of American Pathologists (CAP) Survey results indicated a lack of comparability of GHB test results among methods and laboratories that represented a major obstacle to meaningful implementation of the ADA guidelines. Thus, an AACC subcommittee was formed in 1993 to develop a standardization program that would enable laboratories to report DCCT-traceable GHB results. This program was implemented in 1996 by the National Glycohemoglobin Standardization Program (NGSP) Steering Committee.

APPROACH

We review the NGSP process and summarize progress in standardization through analysis of CAP data.

CONTENT

Since 1996, the number of methods and laboratories certified by the NGSP as traceable to the DCCT has steadily increased. CAP GH2-B survey results reported in December 2000 show marked improvement over 1993 data in the comparability of GHB results. In 2000, 90% of surveyed laboratories reported GHB results as hemoglobin A(1c) (HbA(1c)) or equivalent, compared with 50% in 1993. Of laboratories reporting HbA(1c) in 2000, 78% used a NGSP-certified method. For most certified methods in 2000, between-laboratory CVs were <5%. For all certified methods in 2000, the mean percent HbA(1c) was within 0.8% HbA(1c) of the NGSP target at all HbA(1c) concentrations.

Variability in hemoglobin levels: clinical implications. Case study of the anemic patient

A historical, prospective, multicenter, observational study was conducted on data from October 1996 to December 1997 to determine the impact of hemoglobin (Hb) variability on the interpretation of maintenance anemia management outcomes in hemodialysis patients. Trends in mean Hb levels were retrospectively analyzed to determine whether there were any differences between 1-month Hb averages versus 3- or 6-month rolling averages. Results showed that: (a) Hb measurements exhibit wide variability between patients and within patients, regardless of the assessment method used, and (b) it is difficult to maintain patients within the 1 g/dL Hb spread recommended by NKF-K/DOQI. The largest variations in Hb readings were observed in 1-month readings, while 6-month rolling averages exhibited the least variability. These data illustrate the importance of assessing long-term trends in laboratory data before making incremental or decremental modifications in the anemia prescription.

Bedside Hemoglobinometry in Hemodialysis Patients: Lessons from Point-of-Care Testing

The HemoCue B-hemoglobin test system (HemoCue, Inc., Mission Viejo, CA) is a photometric method for rapid bedside determination of hemoglobin (Hb). We compared the performance of HemoCue measured Hb against Coulter STK-S (CSTK) measured Hb in chronic hemodialysis (HD) patients in two different settings. In the first setting, Hemocue analysis was performed by multiple HD technicians (n = 132). In the second setting, a nurse trained in proper specimen handling performed the HemoCue analysis (n = 74). Simultaneous measurement of Hb by the CSTK method was performed. First setting: Hb was 11.1+/-1.66 (SD) g/dl by CSTK and 11.7+/-2.29 g/dl by HemoCue. The HemoCue method consistently overestimated Hb by an average (SD) of 0.63 (1.267) g/dl (95% CI = 0.42 to 0.85). Hb was overestimated in 25.7% and underestimated in 2.3% of the patients by 1 g/dl or more. Thus, the HemoCue system was accurate within 1 g/dl only 72% of the time. Second setting: HemoCue overestimated Hb by an average (SD) of 0.29 (0.52) g/dl (95% CI, 0.17 to 0.41). Only 4% of all patients had errors in estimation of 1 g/dl or more. Thus, HemoCue was accurate in 96% of the patients within 1 g/dl. After reviewing the two protocols, the primary difference in the two studies was the technique used to obtain the specimens. When performed properly, Hb testing using the HemoCue testing system had a high level of agreement with CSTK. Appropriate training in specimen handling, as well as test performance, will increase accuracy and reliability of bedside hemoglobinometry.

Field evaluation of who hemoglobin color scale in West Java

The results obtained with a WHO hemoglobin (Hb) colour scale were evaluated in a field study in Chibubur district in Java island by comparison with hemoglobin values obtained by an automated blood cell analyzer K-800 (Sysmex. Kobe, Japan). When the color scale test was performed following the instructions for use. Hb values observed were usually higher than the values obtained by the analyzer. Thirty microl blood was loaded on the filter paper and an 60 sec waiting period was used. The sensitivity of results obtained with the color scale was 23.3% (14/60), and specificity was 96.6% (58/60). We propose an additional testing method based on our results.

Evaluation of the HB-Quick: a portable hemoglobinometer

OBJECTIVE

The Hb-Quick is a new portable hemoglobinometer that uses disposable cuvettes to measure the total hemoglobin concentration of capillary, venous, or arterial blood. Therefore, the objectives of this study were 1) to evaluate the performance of this compact, battery-powered hemoglobinometer by assessing its precision, accuracy, and linearity, 2) to determine whether its measurements suffer from interference by hemolysis, bilirubin, fetal hemoglobin, or hemodilution, and 3) to establish whether it can easily be used by clinical personnel with little or no laboratory training.

METHODS

The precision of the test instrument was assessed by making repeated measurements on blood samples. Its accuracy and linearity were evaluated by comparing its measurements with the internationally accepted cyanmethemoglobin method. Samples of whole blood with and without bilirubin, fetal hemoglobin, hemolysis, and hemodilution were also analyzed to determine if any interference occurred when these disturbances were present, and it was placed in physicians' offices to evaluate its use by non-laboratory personnel.

RESULTS

Repeated measurements on blood samples with a wide range of hemoglobin concentrations were consistent with the precision specification (0.25 g/dl). The bias of the new hemoglobinometer was calculated as the mean difference between its readings and measurements with the cyanmethemoglobin method, and its accuracy as the standard deviation of the differences between the two methods. As assessed in this manner, the new hemoglobinometer had a bias of -0.04 g/dl and an accuracy of 0.40 g/dl. The linearity was checked over a hemoglobin concentration range from 0 to nearly 30 g/dl. There was a highly significant linear relationship between its readings and measurements with the cyanmethemoglobin method (slope = 0.997, y-intercept = 0.005, r = 0.999). Complete hemolysis of the sample increased the readings on average by only 0.22 g/dl. Bilirubin (17.5 mg/dl) increased the reading by an average of 0.29 g/dl, and fetal hemoglobin (76.5% HbF) reduced the readings by an average of only 0.035 g/dl. Diluting blood samples with saline also did not appreciably affect its accuracy.

CONCLUSIONS

The new hemoglobinometer is fast and easy to operate. No sample preparation or pipetting is required. To operate the instrument, the user simply allows a drop of blood to fill the disposable cuvette by capillary action and inserts the cuvette into the instrument. The instrument analyzes the 10 microl sample and displays the results in less than 10 seconds. The interference caused by hemolysis, hemodilution with saline, fetal hemoglobin, and bilirubin were too small to be of any dinical importance. Tests in physician's offices indicated that clinical personnel with little or no formal laboratory training could successfully use this device. The observed precision, accuracy, linearity, and freedom from interference indicate that this hemoglobinometer is suitable for near-patient testing in a wide range of clinical settings including physicians' offices.

Hemoglobin and hematocrit: an analysis of clinical accuracy. Case study of the anemic patient

Hemoglobin (Hgb) and hematocrit (Hct) are often used interchangeably to evaluate anemia in dialysis patients. Hgb is the preferred method in most European countries, while Hct is generally used by clinicians in the United States. This article examines the comparative accuracy of these two values, including a same-patient assessment of laboratory samples. These data illustrate that Hgb is a more accurate method of assessing anemia. Using Hgb may help nurses and patients by: (a) decreasing variability in laboratory assessment, (b) avoiding ongoing errors in anemia measurement, (c) decreasing the nursing time spent on anemia management, and (d) increasing the potential for patients remaining in the recommended DOQI target Hgb range of 11 g/dL to 12 g/dL.

[How to achieve analytical reliability of hemoglobinometry]

Three kits of reagents manufactured by RENAM Research and Production Unit provide the analytical reliability of hemoglobinometry. The kits contain: 1) dry powder transforming agent; 2) four calibration standard solutions of hemoglobin cyanate requiring no dilution; 3) three highly purified stable solutions of hemoglobin (simulating human blood) with attested concentrations of hemoglobin from 50 to 200 g/liter.

Accuracy of a portable haemoglobinometer in clinical practice

The haemoglobin (Hb) levels of 100 blood samples submitted to the haematology laboratory of Groote Schuur Hospital were estimated by 3 clinical observers using the Buffalo Medical Specialties (BMS) portable haemoglobinometer. The average error was between 5% and 6% of the laboratory Hb value (0.6 g/dl). It is concluded that the BMS machine, besides being easy to use and giving a rapid result, is also sufficiently accurate for clinical practice.

An assessment of the operating characteristics of Coulter Counter Model S-Plus STKR

BACKGROUND AND METHODS

The operating performance of the Coulter Counter S Plus STKR was evaluated in two hospital laboratories in Rome and in Florence. Experimental design conformed to both the ICSH and NCCLS Standards for the evaluation of hematologic analyzers, and to the ECCLS guidelines for the multicenter evaluation of analyzers in clinical chemistry.

RESULTS AND CONCLUSIONS

Cell counts in K3 EDTA were unchanged over 6 hours at room temperature and 72 hours at 4 degrees C, while MCV, MPV and leukocyte differentials were far less stable. Carry over, precision and linearity met the manufacturer's specifications, while a satisfactory relative accuracy was demonstrated by determining reference values on an adult reference group and by comparing the instrument with the previous model S Plus IV D. The accuracy of the leukocyte differentials was evaluated by the microscope reference method, and our results seemed to validate the hypotheses that the STKR model counts: i) eosinophils, basophils and banded neutrophils among GR; ii) variant lymphocytes among LY, and iii) various abnormal cells among mononuclear cells. However, in spite of this statistical significance, some difficulties in correctly classifying the mononuclear population were demonstrated.

The distribution of selected hematology measurements in the CAP survey

Investigation of the 1978 CAP Hematology Survey results for hemoglobin, hematocrit, erythrocyte count, leukocyte count, prothrombin time, and partial thromboplastin time with respect to the assumption of normality and the method for detecting outliers was performed. The findings indicate that the assumption of normality, while not exactly valid, is reasonable for the purposes of the Survey, but that the method of determining outliers may be too stringent in the case of hemoglobin, hematocrit, erythrocyte count, and leukocyte count, and not appropriate for prothrombin time and partial thromboplastin time. These findings are similar to those reported earlier for selected chemistry and immunology constituents in the CAP Survey.

The status of methods of calibration in hematology

Three years ago, the authors described methods for calibration and quality control of Coulter automated hematology instruments. These and other methods have received fairly widespread use in hematology laboratories. The effectiveness of such use was tested through special questionnaires conducted by the College of American Pathologists in 1978. Current information indicates no clear-cut advantages between fresh whole blood and preserved-cell control materials when properly used for calibration or quality control procedures. Minor but troublesome differences persistently appear between manual or semiautomated methods and in results on fully automated systems. Likewise, daily internal quality control may be monitored by preserved cells or by continuous process control using patient samples. The various systems for calibration and quality control have certain advantages and disadvantages.

Comparison of the Sahli and grey wedge haemoglobinometers

Experiment confirms that the MRC grey wedge photometer is better for haemoglobinometry than the Sahli haemoglobinometer. However, there is considerable observer variation and the precision of those who undertake haemoglobinometry should be studied by analysis of duplicates. Only in this way can the significance of any measurements obtained be assessed.

[How effective are simple laboratory tests (Hb, BSG) in the early diagnosis of stomach neoplasms]

Up to now only early resection has proven of value in healing gastric carcinoma. It is therefore mandatory that the pathologic lesion be diagnosed as early as possible. Thus, patients with persistent epigastric complaints under symptomatic treatment should undergo endoscopy even if blood parameters are still within normal limits. The fact that, among all our gastric cancers diagnosed in 1977 by endoscopy, 23% were classified as early cancers indicates that the method is well suited to establishing true early diagnosis.