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At least 19 recordsLinked to original sources
PubMed1995

A strategy to promote rational clinical chemistry test utilization.

There is abundant evidence that clinical chemistry laboratory tests are over-ordered in North America, but there does not seem to be an effective corrective strategy that has a prolonged effect. The goal of this study was to design one that had a prolonged effect. Using a pre- and post-intervention survey study design, the authors observed the effect of physician education followed by a ban on test-panel ordering of common clinical chemistry tests, reinforced by written reminders to physicians not heeding the ban, on ordering patterns (tests per specimen), and total numbers of these tests ordered. Panels of > 16 common biochemistry tests per specimen were reduced from 15% to 6% of orders for inpatients and from 44% to 11% for outpatients 1 year after the implementation of the ban on test-panel ordering. However, the ban had little effect on the ordering rates for panels of 7 common tests. Educational exercises (newsletters and lectures) had no effect. The authors conclude that a ban on test-panel (profile) ordering reinforced by continuing reminders to nonconforming physicians is an effective means of reducing clinical chemistry test usage over the long term. A 38% reduction of common biochemistry tests ordered was achieved. However, overall costs savings were modest. Nevertheless, the authors conclude that the cost-effective use of the clinical pathology laboratory by careful selection of tests in an essential part of a medical trainee's education.

Biochemistry↗
PubMed1999

Utilisation of clinical chemistry tests, with special reference to lipid profile, in disease management in a Nigeria setting.

BACKGROUND: Previous reports show that most Nigerian patients have not been subjected to detailed clinical chemistry investigations, especially lipid profiles during the course of their management. OBJECTIVE: To evaluate the level of utilisation of clinical chemistry tests, especially lipid profile, in the management of certain selected diseases. DESIGN: Analytical study of clinical chemistry tests done in patients with hypertension, liver diseases, nephrotic syndrome and peripheral neuropathy and in control subjects between January 1995 and December 1996. SETTING: Department of Chemical Pathology, Nnamdi Azikiwe University Teaching Hospital, Nigeria. RESULTS: The distribution of the chemical pathology tests in all the disease groups varied significantly. The mean values of TC, LDLC, TG and VLDLC increased while HDLC/TC ratio reduced in the hypertensive patients when compared with the control subjects. The variations in the mean values of HDLC and urea among the hypertensive patients and controls were not statistically significant. CONCLUSION: Our findings suggest an increase in the risk of cardiovascular disease in hypertensive patients and these observations should be remembered by all clinicians and other health workers during the management of hypertension and other diseases. We recommend that the investigations of lipid and lipoprotein indices and other clinical chemistry parameters should be encouraged during management of disease in Nigerians.

Adult↗
PubMed2006

Influence of hemolysis on routine clinical chemistry testing.

BACKGROUND: Preanalytical factors are the main source of variation in clinical chemistry testing and among the major determinants of preanalytical variability, sample hemolysis can exert a strong influence on result reliability. Hemolytic samples are a rather common and unfavorable occurrence in laboratory practice, as they are often considered unsuitable for routine testing due to biological and analytical interference. However, definitive indications on the analytical and clinical management of hemolyzed specimens are currently lacking. Therefore, the present investigation evaluated the influence of in vitro blood cell lysis on routine clinical chemistry testing. METHODS: Nine aliquots, prepared by serial dilutions of homologous hemolyzed samples collected from 12 different subjects and containing a final concentration of serum hemoglobin ranging from 0 to 20.6 g/L, were tested for the most common clinical chemistry analytes. Lysis was achieved by subjecting whole blood to an overnight freeze-thaw cycle. RESULTS: Hemolysis interference appeared to be approximately linearly dependent on the final concentration of blood-cell lysate in the specimen. This generated a consistent trend towards overestimation of alanine aminotransferase (ALT), aspartate aminotransferase (AST), creatinine, creatine kinase (CK), iron, lactate dehydrogenase (LDH), lipase, magnesium, phosphorus, potassium and urea, whereas mean values of albumin, alkaline phosphatase (ALP), chloride, gamma-glutamyltransferase (GGT), glucose and sodium were substantially decreased. Clinically meaningful variations of AST, chloride, LDH, potassium and sodium were observed in specimens displaying mild or almost undetectable hemolysis by visual inspection (serum hemoglobin < 0.6 g/L). The rather heterogeneous and unpredictable response to hemolysis observed for several parameters prevented the adoption of reliable statistic corrective measures for results on the basis of the degree of hemolysis. CONCLUSION: If hemolysis and blood cell lysis result from an in vitro cause, we suggest that the most convenient corrective solution might be quantification of free hemoglobin, alerting the clinicians and sample recollection.

Artifacts↗
PubMed1996

Strategies to promote rational clinical chemistry test utilization.

OBJECTIVE: To critically review the elements of laboratory services that result in inappropriate ordering of clinical chemistry tests and the efficacy of corrective interventions. METHODS AND RESULTS: In our experience, inappropriate use of laboratory services derives from multiple factors, including the use of multitest profiles, organ- or disease-specific test panels, indiscriminate ordering, standing orders, excessive reporting delays, poor audit trails of test requests, rigid group test ordering, failure to eliminate obsolete tests, and some features of computer software design. Educational strategies can be effective in modifying test-ordering patterns, provided there is sustained feedback to physicians. Careful design of requisitions and the use of disease-specific algorithms have also proven effective. CONCLUSION: Limited resources must be directed to where they are most effective by optimizing laboratory work-flow from test ordering to reporting, to avoid practices that promote inappropriate laboratory use.

Chemistry, Clinical↗
PubMed1986

The application of two-dimensional centrifugation to clinical chemistry testing.

We have developed a new clinical chemistry analyzer, the VISION System, which uses centrifugal force to separate whole blood, measure reagent and plasma volumes, and complete all steps required for a spectrophotometric analysis. The system is based on a multichambered test pack containing liquid reagents, which can be centrifuged in two planes oriented at right angles to each other. The analyzer regulates the temperature, timing and optical measurements for up to 10 different test packs in the same run. We have demonstrated good precision and accuracy on 6 clinical chemistry analytes, 2 enzymes, potassium and theophylline using this system.

Blood Chemical Analysis↗
PubMed1990

Differential application of rate and delta check on selected clinical chemistry tests.

Through the present delta value check used in quality control programs is a powerful tool for detecting random errors in clinical chemistry analysis, it has some problems, such as missed true errors and delays in reporting time, because it also has the potential of showing erroneous positive results. Recently, new calculation methods for delta check with delta difference, delta percent change, rate difference, and rate percent change have been suggested by Lacher and Connelly (Clin Chem 34:1966-1970, 1988). Based on this new delta check method, we made the new criteria of which calculation method is applied to the clinical chemistry tests, i.e., the differential application of rate and delta check, and selectively applied the new method to 17 chemistry tests in order to solve the above problems. The applied criteria were the time dependence of the test item and the coefficient of variation of the absolute delta difference. Calcium, inorganic phosphorus, total protein, albumin, sodium, potassium, and chloride were classified as delta difference calculation method group; glucose and cholesterol as delta percent change group; creatinine, total and direct bilirubin as rate difference group; and urea nitrogen, uric acid, ALP, ALT, and AST as rate percent change group. With the previous criteria by Whitehurst et al. (Clin Chem 221:87-92) for 5045 specimens, the check-out rate was 47.8% (2,411 out of 5,045), and the positive predictive value was 0.41% (10 out of 2,411). For the new criteria, the check-out rate was 12.7% (621 out of 5,045), and the positive predictive value was 1.8% (nine out of 621).(ABSTRACT TRUNCATED AT 250 WORDS)

Albumins↗
PubMed2006

Influence of the needle bore size used for collecting venous blood samples on routine clinical chemistry testing.

BACKGROUND: Despite remarkable advances in technology and laboratory automation, results of laboratory testing still suffer from a high degree of preanalytical variability. Although there is no definitive evidence, the use of small-gauge needles for venipuncture is usually discouraged to reduce the chance of producing unsuitable specimens. METHODS: The purpose of this investigation was to assess the influence of the needle size used to collect venous blood on the measurement of 14 common analytes, including free hemoglobin, the most representative enzymes, protein-bound substances and electrolytes. Results for venous blood samples collected from 20 fasting voluntary physicians using either a 23- (0.60 mmx19 mm) or 25-gauge-needle (0.50 mmx19 mm) butterfly devices with polyvinyl chloride tubing (1.40 mmx300 mm) were compared with reference specimens collected using a 21-gauge-needle (0.80 mmx19 mm) butterfly device with polyvinyl chloride tubing (1.40 mmx300 mm). RESULTS: All means for paired samples collected using the smaller needles did not differ significantly from the reference specimen by paired Student's t-test analysis. Passing-Bablok regression analysis and Pearson's or Spearman (creatine kinase, aspartate aminotransferase, alanine aminotransferase and chloride) correlation were acceptable for most of the analyses, although a lower correlation coefficient was observed for electrolytes. In addition, when expressed as a percentage of the mean for paired samples, the s(y,x) value exceeded the desirable bias for free hemoglobin, glucose, lactate dehydrogenase, aspartate aminotransferase, sodium, chloride, calcium and magnesium (in samples collected using both 23 G and 25 G needles) and potassium (in samples collected using a 25 G needle). Although Bland-Altman plot analysis and +/-1.96 SD agreement intervals for the set of differences between values was acceptable overall, the bias was rather broad for free hemoglobin and several critical electrolytes (calcium, chloride, potassium, sodium), exceeding the respective limits for desirable bias. CONCLUSIONS: The results of our investigation indicate that 23 G needles, if handled correctly, will not introduce any statistically or clinically significant error to the measurement results compared to a 21 G needle. For the 25 G needle, we observed increased variability for potassium compared to a 23 G needle. Small-bore needles of 25 G or less cannot be universally recommended when collecting venous blood for clinical chemistry testing and should be reserved for selected circumstances, such as in patients with problematical venous accesses and newborns. In such cases, however, the bias introduced by the use of smaller needles should always be taken into consideration when interpreting test results.

Adult↗
PubMed2004

Corrections of clinical chemistry test results in a laboratory information system.

CONTEXT: The recently released reports by the Institute of Medicine, To Err Is Human and Patient Safety, have received national attention because of their focus on the problem of medical errors. Although a small number of studies have reported on errors in general clinical laboratories, there are, to our knowledge, no reported studies that focus on errors in pediatric clinical laboratory testing. OBJECTIVE: To characterize the errors that have caused corrections to have to be made in pediatric clinical chemistry results in the laboratory information system, Misys. To provide initial data on the errors detected in pediatric clinical chemistry laboratories in order to improve patient safety in pediatric health care. DESIGN: All clinical chemistry staff members were informed of the study and were requested to report in writing when a correction was made in the laboratory information system, Misys. Errors were detected either by the clinicians (the results did not fit the patients' clinical conditions) or by the laboratory technologists (the results were double-checked, and the worksheets were carefully examined twice a day). No incident that was discovered before or during the final validation was included. On each Monday of the study, we generated a report from Misys that listed all of the corrections made during the previous week. We then categorized the corrections according to the types and stages of the incidents that led to the corrections. RESULTS: A total of 187 incidents were detected during the 10-month study, representing a 0.26% error detection rate per requisition. The distribution of the detected incidents included 31 (17%) preanalytic incidents, 46 (25%) analytic incidents, and 110 (59%) postanalytic incidents. The errors related to noninterfaced tests accounted for 50% of the total incidents and for 37% of the affected tests and orderable panels, while the noninterfaced tests and panels accounted for 17% of the total test volume in our laboratory. CONCLUSION: This pilot study provided the rate and categories of errors detected in a pediatric clinical chemistry laboratory based on the corrections of results in the laboratory information system. A direct interface of the instruments to the laboratory information system showed that it had favorable effects on reducing laboratory errors.

Child↗
PubMed1997

In vitro interference of the red cell substitute pyridoxalated hemoglobin-polyoxyethylene with blood compatibility, coagulation, and clinical chemistry testing.

OBJECTIVES: Pyridoxalated hemoglobin-polyoxyethylene (PHP) is a prototypical red cell substitute approved for phase I studies. Peripheral blood smears of human blood mixed with PHP in 1 to 4 g/dL concentrations showed dose-dependent red cell aggregation and rouleaux. Whether this aggregation limits interpretation of blood compatibility testing and whether the intense coloration of serum or plasma containing PHP affects routine coagulation and clinical chemistry measurements was tested. DESIGN: In vitro studies. SETTING: University hospital laboratory. PARTICIPANTS: Four healthy volunteers, blood types A, B, AB, and O. All were Rh+. MEASUREMENTS AND MAIN RESULTS: ABO typing, Rh typing, and antibody screening and coagulation studies were performed on blood: PHP admixtures having final concentrations of 1, 2, and 4 g/dL. For clinical chemistry interference studies, known concentrations of analytes were added to a serum matrix containing PHP. ABO (forward) and Rh typing showed no interference in the three concentrations tested. Reverse ABO typing and antibody screening showed rouleaux at 4 g/dL, which corrected with routine saline replacement. Partial thromboplastin time (PTT), prothrombin time (PT), and fibrinogen showed no clinically significant differences from the controls. Results for electrolytes, renal function analytes, and markers of cardiac injury were acceptable by standard laboratory methods. However, results of liver function tests were unacceptable in PHP-containing specimens. CONCLUSIONS: PHP-induced aggregation was observed with high PHP concentration; however, compatibility testing was not affected because agglutination was corrected by saline replacement, which is standard practice. Although routine blood banking, coagulation, and most clinical chemistry analytes can be measured reliably, alternative methods and strategies are needed for assessing liver function in the presence of PHP.

Blood Coagulation↗
PubMed1983

Effects of Fluosol-DA (artificial blood) on clinical chemistry tests and instruments.

Artificial blood must be added to the list of therapeutic agents that produce interference with diagnostic laboratory tests. Fluosol-DA (Alpha Therapeutic Corp., Los Angeles, CA), a stable 20% emulsion of perfluorocarbons in aqueous medium, is being evaluated in clinical trials as a blood substitute in the United States. We investigated its effects in blood and serum samples on test results and instruments in the clinical chemistry laboratory. The 20% emulsion was added to blood or serum specimens in amounts corresponding to the replacement of in-vivo plasma volumes of 10-50%, concentrations that would be expected in blood samples obtained from patients who have received Fluosol. Observed interferences mimicked those caused by high triglyceride concentrations in serum specimens: interference with chemical reactions and generation of spurious absorbance readings because of turbidity. These types of errors are often additive, and the cumulative effect may cause either erroneously high or low values for the analytes concerned. Because Fluosol may be used widely, although infrequently, for patients refusing blood transfusions on religious grounds and for patients with rare antibodies to red blood cells who require transfusion, laboratories analyzing specimens containing Fluosol should be aware of the potential errors.

Alkaline Phosphatase↗