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The reference values of the most commonly used parameters in hematology were evaluated in a metaanalysis using practices of a group of major hospitals in Switzerland and in detail review of the literature. Extensive differences of the reference values have been noted being caused mainly by selection of different patient/control collectives. Whenever possible, reference values were separately evaluated for age, gender and race. The reported reference values approximated a Gauss distribution allowing for statistical evaluation accordingly. Due to recent standardization (ICSH and NCCLS), differences caused by instrumentation and preanalytics were found to be of less importance. Our presented validated reference values in hematology should allow for better discrimination of classical hematological disease entities such as an iron deficiency anemia, thalassemia and hemolysis.
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Reference concentrations of metals are the basis for risk assessment studies and for estimation of type and magnitude of environmental and occupational exposure. Urine is often used as a specimen for monitoring studies, as it plays an important role in the elimination of various substances from the body and in addition it can be collected easily. Therefore, the urinary levels of seven trace elements (Al, Co, Cr, Mo, Nb, Ni, Ti) were determined by atomic spectrometric methods (ICP-MS and GFAAS) in 100 urine samples of the Viennese population. The obtained creatinine adjusted concentrations (medians) are in microg/g 6.1, 1.5, 1.1, 46.2, 0.4, 0.1, and 8.0 for Al, Co, Cr, Mo, Nb, Ni, and Ti, respectively.
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INTRODUCTION: The reference values (RV) of biological indicators are used in the interpretation of the results of such indicators in individuals occupationally exposed to chemical agents. The Brazilian Group for the Establishment of Reference Values has worked on these definitions for the purpose of establishing RVs for several bioindicators in various regions of the country. In the present study, the RV for carboxyhemoglobin (COHb) was determined for the South of Minas Gerais. MATERIAL AND METHOD: The COHb was analyzed by the Beutler and West (1984) spectrophotometric method, optimized in our laboratory. In all the samples, analyses of some biochemical and hematological parameters were made to evaluate the health condition of a population of 200 volunteer non-smokers occupationally not exposed to CO. Each individual answered a questionnaire to obtain data pertinent to the interpretation of the results. The reference values were expressed as mean values +/- standard deviation, with a 95% confidence interval, and an upper reference value. The statistical distribution of the results was made so as to enable comparisons between the results of groups of workers, rather than individual evaluations, to be made. RESULTS AND CONCLUSIONS: The mean value +/- standard deviation was 1.0% +/- 0.75; the 95% confidence interval was 0.9-1.1% and the upper reference value was 2.5%. By the t Student test (p < or = 0.05), no difference was detected between the values related to sex, age or ingestion of alcoholic beverages. The reference values obtained were close to those reported for others countries.
The paper presents an integrated system if guide values, represented by reference values, action levels, limit values, theoretically able to cover the interpretation of all the data from biological monitoring. This practice, requires in fact accurate values to which refer for demonstrating exposures to xenobiotics, and their early health effect. The procedures to select subjects, to control pre analytical and analytical factors, to apply correct statistical methods for establishing accurate reference values are recalled, and the relationship between the different guide values discussed.
A review describing the fallacies of the concept of normal values and the reasons for its substitution with reference values. The "reference value philosophy", its terminology and recommended practical procedures are presented and it is warned not to use incorrect terms such as "normal reference range". The concepts of health and disease are discussed from the point of view of the laboratory. Reference values are not always derived from "healthy" persons. In order to be comparable, reference values and observed (i.e. patient) values should be produced in the same way, using the same analytical procedure, quality control, etc. The influence of preanalytical factors such as food intake, posture, use of tourniquet and freezing and storing samples is great and necessitates standardisation of specimen collection. Strategies for the selection of reference individuals are presented and the reasons and methods for subdivision of the data are described. Descriptions are also given of the individual reference values and the statistical treatment of collected data including multivariate analysis. Finally, the reporting of observed values in relation to reference values is discussed. There is a trend to avoid the use of the reference interval because of the temptation to regard the values falling outside it as pathological.
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Dietary reference values for food energy for population groups are set at the level of average energy requirement without a safety margin to avoid any risk of inadequate energy intake. Average energy requirements and hence reference values for energy can be determined from either energy intake data or energy expenditure. In this article, the present reference values for energy of 12 countries, the FAO/WHO/UNU and the Scientific Committee on Food (SCF/EC) are compared regarding the level of their standards and underlying concepts. Methods for estimating energy requirements of different population groups and data sources for reference values for energy are summarized. Furthermore, reference values for energy for males and females of all ages are presented in separate graphs. The comparison of national standards illustrates that the level of reference values for energy for individual countries is dependent on variables such as methodology, data sources, allowances for physical activity, reference body weight, and age range. Standards for adolescents and elderly persons reveal that differences in reference values are most apparent in population groups for which only limited data on energy requirements are available. Although it is not possible to evaluate the adequacy of reference values for energy by comparing data of different countries, many differences in the level of reference values can be explained on the basis of underlying concepts.
Reference values for 18 plasma chemical variables in blue neck ostriches (Struthio camelus australis, n = 60, age 24-36 mo) were established for use in veterinary clinical practice using nonparametric statistics. The following values were established for the percentiles P2.5 and P97.5: sodium 147-157 mmol/L, calcium 2.4-4.8 mmol/L, inorganic phosphate 1.3-2.3 mmol/L, chloride 94-105 mmol/L, glucose 10.3-13.7 mmol/L, urea 0.5-0.8 mmol/L, uric acid 351-649 mumol/L, bile acids 8-33 mumol/L, total protein 39-56 g/L, albumin-globulin ratio 0.45-0.59, osmolality 304-330 mOsm/kg, alkaline phosphate 69-217 IU/L, aspartate aminotransferase 243-418 IU/L, gamma-glutamyltransferase 0-1 IU/L, creatine kinase 1648-4894 IU/L, glutamate dehydrogenase 8-17 IU/L, and lactate dehydrogenase 860-2236 IU/L. The plasma calcium concentration was significantly (P < 0.001; r = 0.74) related to the total protein concentration and an adjustment-formula for calcium was derived: adjusted Ca (mmol/L) = Ca (mmol/L)--0.09 TP (g/L) + 4.4. The influence of blood sample treatment on the plasma potassium concentration as seen in other avian species was demonstrated in a separate experiment, emphasizing the need to separate plasma and cells immediately after collection in avian blood samples.
This article describes the working principles and working procedures of the Commission on Human Biological Monitoring, which was established in 1993 as a joint commission of the Federal Health Office (Bundesgesundheitsamt) and the Federal Environmental Agency (Umweltbundesamt) in Germany. One of the main tasks of the commission is to develop scientifically based criteria for the application of human biological monitoring and for the evaluation of human monitoring data in environmental medicine. In principle, two different kinds of criteria are recommended: (a) reference values and (b) human biological monitoring values (HBM values). Reference values are intended to indicate the upper margin of the current background exposure of the general population to a given environmental toxin at a given time. Reference values can be used to identify subjects with an increased level of exposure (in relation to background exposure) to a given environmental toxin. However, reference values do not represent health-related criteria for the evaluation of human biological monitoring data. HBM values are derived from human toxicology and epidemiology studies and are intended to be used as a basis for a health-related evaluation of human biological monitoring data. Usually the commission recommends two different HBM values: HBM I, the concentration of an environmental toxin in a human biological material (usually blood, serum, plasma, or urine) below which there is--according to the knowledge and judgement of the commission--no risk for adverse health effects in individuals of the general population: and HBM II, the concentration of an environmental toxin in a human biological material (usually blood, serum, plasma, or urine) above which there is--according to the knowledge and judgement of the commission and with regard to the environmental toxin under consideration--an increased risk for adverse health effects in susceptible individuals of the general population. The HBM I value can be considered a kind of alert value (from the toxicological point of view), whereas the HBM II value represents a kind of action level, at which attempts should be undertaken to reduce the level of exposure immediately and to carry out further medical examinations. Values between HBM I and HBM II should be considered a warning signal of the need to control the analytical measurement and to reduce the level of exposure of the concerned individual as reasonably as is achievable. At present, reference and HBM values are available for lead in blood, for cadmium and mercury in blood and urine, and for pentachlorophenol in plasma/serum and urine. Reference values have been established for some polychlorinated biphenyls in blood and plasma as well as for hexachlorocyclohexane and hexacholorobenzene in blood as well as for some organochlorine in human milk.
The determination of Reference Values (R.V.) in biological fluids is a hard task for analytical laboratories because: (1) the instrumentation must have detection limits adequate to low concentration levels; (2) the analytical method adopted should reduce the sample manipulation in order to avoid the cross-contamination; (3) the control of pre-analytical factors must assure low levels of blank in term of absolute value and variability. The possibility to analyze the samples without pretreatment by using hyphenated techniques with low detection limits it is the main tool to obtain reliable reference values. The large number of papers recently published and the reported examples show that the determination of metallic species in biological fluids can be successfully performed by ICP-MS in its different configuration and that mass spectrometry can be considered as reference technique in this specific application field.
The factors that influence reference values are briefly reviewed using our experimental data. The factors can be divided into the following 3 subfactors: analytical technology, selection of so called healthy person and statistical method. The most large effect came from a variety of physiological conditions in healthy persons, i.e., age, sex, diurnal and menstrual rhythms, drinking and smoking habits, diet, physical exercise, posture, tourniquet etc. A new concept of tow-step reference values "the basal value and the equivocal value" is postulated from the studies of the effect of these physiological conditions. The effects of the statistical methods for obtaining the distribution type of data of normal reference group and the 95% reference range were not so large. Then, we conclude that the reference values or the reference ranges should be made in your own laboratories using carefully selected healthy persons even if 30 or 50 small numbers are used.
Reference values for common laboratory tests were determined as part of a cross-sectional survey of 70 year olds in Jerusalem in 1991. Subjects were systematically chosen from electoral lists. They were extensively interviewed regarding demographic, socioeconomic and health characteristics. Subsequently, 456 underwent a thorough medical examination including hematologic, biochemical and endocrinologic testing. Analysis of disease-specific mortality and hospital morbidity at 3 year follow-up proved these subjects to be representative of the overall Jerusalem Jewish population of 70 year olds. Test-specific reference subgroups were determined to exclude effects of known diseases and drug consumption. Reference values in these subgroups differ significantly from reference values currently used for adults without regard to age. The determination of disease for subjects provided the opportunity to identify changes that might reflect normal aging and those that might be affected by subclinical pathology. Interpretation of laboratory testing of older adults must consider the age-related differences in reference values.
Haematological and biochemical reference values were established from 45 clinically healthy koalas. Statistical analysis revealed no significant differences for sex and season of sampling. Immature koalas had significantly higher alkaline phosphatase and inorganic phosphate values, and significantly lower total protein concentrations due to low globulins values. Enzyme reference values tended to be wide and could limit their usefulness in detecting disease. In the reference values for leukocytes, neutrophils and lymphocytes, the inclusion of low values which were not actually seen may interfere with the detection of reduced levels due to disease.