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PubMed1995

Review of trace elements in blood, serum and urine for the Czech and Slovak populations and critical evaluation of their possible use as reference values.

The availability of accurate trace element reference values in human tissues represents an important indicator to the health status of the general population and occupational groups exposed to trace elements. The EURO TERVIHT project (Trace Element Reference Values in Human Tissues) aims to establish and compare trace element reference values in tissues from inhabitants of the European countries as baseline values for clinical/toxicological assessment studies. In this context, one of the first steps considered is the critical evaluation (state of the art) of existing literature on trace element reference values in blood, serum and urine in the general population of each European country. This paper reviews the Czech and Slovak situation by assessing studies carried out in these countries for Al, As, Cd, Co, Cr, Cu, F, Mn, Hg, Ni, Pb, Rb, Sc, Se, V and Zn in blood, serum and urine. These studies show that most of the data available do not meet criteria designed recently for deriving reference intervals, especially regarding the number of subjects, the age of population sample studies as well as the use of appropriate sampling techniques and quality assurance procedures. Elements which present the highest potential risk for health in Czech and Slovak populations and for which reference values should be urgently established are: Cd, Hg, Pb (major pollutants); As, Cr, Ni (carcinogenic metals); Al, F, Mn, Tl, V (released into the environment by coal combustion and other industrial activities); Pt (increasing use of Pt catalyst in petrol-driven automobiles); essential trace elements such as I, Se and Zn for which a deficiency in Czech and Slovak populations was detected or is suspected.

Czechoslovakia↗
PubMed2005

The Calgary Depression Rating Scale for schizophrenia in a healthy control group: psychometric properties and reference values.

BACKGROUND: Assessment of depression in schizophrenia is of great importance as depressive signs and symptoms and suicidality are highly prevalent in patients with schizophrenic disorders. The Calgary Depression Rating Scale (CDSS) is the standard assessment instrument for that purpose due to its proven reliability and validity. However, so far no reference values derived from an adequate healthy sample have been published. METHODS: The present study analyzed CDSS item scores and summary scores in 154 healthy subjects (49% female, mean age 32.8+/-11.7 years) selected from studies as controls for schizophrenic patients. RESULTS: The total CDSS score was 2.6+/-2.7 (range 0-12), about 1/3 of healthy subjects had scores=0. Gender differences were observed with respect to "early awakening" and "suicidal ideation" with higher scores in females. Total CDSS scores (r=-0.17, P=0.03) and single items were slightly negatively correlated with age. The psychometric properties of the CDSS scale were satisfying (corrected item-score correlations r(tc)=0.33-0.61, internal consistency Cronbach's alpha=0.76, one-dimensional factor structure). CDSS total scores showed a skewed distribution fitting the upper part of a normal distribution. Based on the empirical distribution of CDSS values, reference values were listed for the total group of healthy subjects, and for females and males separately. CONCLUSIONS: The results corroborate the favourable psychometric properties of the CDSS found previously in clinical samples in a healthy control group. The reference values reported here can assist the clinical use and interpretation of CDSS values and emphasize the usefulness of the CDSS for a thorough assessment of depression and suicidality in schizophrenia.

Adult↗
PubMed2006

[Reference values for anaemia in the elderly].

According to the reference values of the World Health Organization (WHO), anaemia is defined as a haemoglobin (Hb) level < 8.1 mmol/l in men and < 7.5 mmol/l in women. Lower reference values are often used in older patients because many doctors consider a decreased Hb level to be physiological in advanced age. However, Hb values under the WHO reference values are associated with increased mortality in older persons. Moreover, a cause of the anaemia is found in > 80% of older persons with anaemia if further diagnostic tests are done. Decreased Hb levels are also associated with functional impairments such as mobility disorders. These findings apply not only to severely decreased Hb levels but also to Hb levels that are only slightly below the WHO reference values. Correspondingly, increased erythropoietin levels are seen in older persons with severely decreased Hb levels as well as in older persons with slightly decreased Hb levels. Thus, a decrease in the Hb level in advanced age is not physiological and the WHO reference values for anaemia are also valid for older persons.

Age Factors↗
PubMed1990

Biochemical reference values in elderly black subjects.

Biochemical reference values for the black age group of greater than or equal to 65 years were determined from the black urban population of the Orange Free State. Biochemical investigations performed were those included in the Sequential Multiple Analyser Computer profile because it includes the 20 most requested clinical chemistry investigations. Most of the reference values corresponded to values for the same age groups in the Western world. There was no age-related rise in the alkaline phosphatase values, which suggested absence of occult Paget's disease. Reference values for serum total protein and globulin were found to be higher than values derived from elderly white groups.

Age Factors↗
PubMed2001

[Reference values of serum lipid].

The guideline for the reference value of serum lipid(total cholesterol, LDL-cholesterol, HDL-cholesterol and triglyceride) was proposed by the Japan Atherosclerosis Society in 1997. These values are utilized for the diagnosis and treatment of hyperlipidemia to protect patients from ischemic heart disease. The upper limit of reference value was not determined by the 95 percentile range from healthy subjects, but on the basis of clinical data on serum lipid in the Japanese. This way to determine the reference value will be suitable in case of lipid, because there is a tendency to increase cholesterol level in the Japanese for these thirty years. The standardization for each lipid assay is crucial. The CDC-established Reference Methods for measuring total cholesterol(TC), HDL-C. LDL-C, and triglyceride(TG) are used to set reference values for the serum pools used for LSP(Lipid Standardization Panel) standardization. In Japan, the routine methods for cholesterol and triglyceride have been proposed by the special committee in the Japan Society of Clinical Chemistry. In contrast, homogeneous assay for HDL- and LDL-C, which are used routinely at present, have still some problems in the point of accuracy. A new ELISA for Lp(a) has been developed using antibody not reacting to kringle IV type 2. Its standardized assay, thus, will be available sooner or later. With respect to other lipid-related test such as RLP(remnant-like particles) and oxidized LDL, it is necessary to accumulate more clinical data for the determination of reference value.

Apoproteins↗
PubMed1999

Musculoskeletal function assessment: reference values for patient and non-patient samples.

Although researchers and clinicians are encouraged to use health-status questionnaires to evaluate, monitor, and modify care, their use is hindered by the lack of reference values. Without reference values, it is difficult to interpret or evaluate questionnaire scores. In this paper, we present reference values for the Musculoskeletal Function Assessment, a 101-item health-status questionnaire designed and validated for patients with a broad range of musculoskeletal disorders. We describe reference values for two samples: non-patients (n = 123) and patients with isolated extremity injuries (n = 274). For the non-patient sample, descriptive statistics are presented by age and gender, measured at one point in time. For the patient sample, descriptive statistics are provided for seven Orthopaedic Trauma Association/AO diagnostic groups, measured at two points in time. Reference values for changes in the Musculoskeletal Function Assessment total score are described for patients 3 and 9 months and 6 and 12 months after injury. The total scores by post-injury interval, across the diagnostic groups, are significantly better at follow-up than at baseline (p = 0.00). Reference values for changes in total scores are also described in terms of these diagnostic groups across post-injury intervals. Musculoskeletal Function Assessment total scores for Orthopaedic Trauma Association/AO diagnostic groups are significantly better at follow-up than at baseline (p < 0.03). Changes in the total score are also tested for responsiveness with use of standardized response means. Large effects are demonstrated for patients completing the Musculoskeletal Function Assessment at 3 and 9 months (1.03), and small effects are demonstrated for those completing it at 6 and 12 months (0.49). Moderate and large effects are demonstrated for Orthopaedic Trauma Association/AO diagnostic groups across post-injury intervals.

Adolescent↗
PubMed2006

Revised reference value for pentachlorophenol in morning urine.

Reference values are continuously derived by the Human Biomonitoring Commission of the German Federal Environment Agency to give help in assessing the exposure of individuals or population groups in comparison to the background exposure. As environmental conditions may change reference values should be checked periodically and they have to be updated, if new data become available. The results of the German Environmental Survey 1998 (GerES III) showed the decreasing pentachlorophenol (PCP) exposure of the German adult population. Therefore, the reference value for PCP in morning urine was lowered: from 8 to 5 microg/l for adults (aged 18-69 years) living in homes where wood preservatives had not been used.

Adolescent↗
PubMed2002

Polychlorinated biphenyls and hexachlorobenzene in full-term neonates. Reference values updated.

OBJECTIVE: To determine actual reference values of polychlorinated biphenyls (PCBs) and hexachlorobenzene (HCB) in full-term neonates. PATIENTS AND METHODS: Cord blood samples were taken from 200 healthy, full-term neonates in 1998. Blood specimens were immediately centrifuged, and serum was stored in glass tubes at -20 degrees C up to analysis. Six PCB congeners (IUPAC No. 28, 52, 101, 138, 153, and 180) and HCB were determined with capillary gas chromatography with electron capture detection. Study groups were tested on mean differences with Wilcoxon's test of independent samples. The 95th percentiles by rank were calculated as reference values. RESULTS: One sample was excluded from further evaluation because of unusually high PCB concentrations. Personal data of the remaining 199 newborns showed 106 male and 93 female neonates. Mean gestational age was 40 weeks (range 38-43 weeks), mean birth weight was 3,450 g (2,300-5,060 g). The concentrations of the lower-chlorinated PCB congeners 28, 52, and 101 were below the detection limit with exception of two probes. Reference values (95th percentile by rank) of the higher-chlorinated PCB congeners and HCB were as follows: PCB 138, 0.5 microg/l; PCB 153, 0.5 microg/l; PCB 180, 0.4 microg/l; and HCB, 0.5 microg/l. CONCLUSIONS: The results of the present study clearly demonstrate a further decline in the prenatal uptake of PCBs and HCB since 1994-1995. During the past 15 years, a 75% decline in the prenatal burden with PCBs and a 90% reduction in the burden with HCB could be demonstrated.

Chromatography, Gas↗
PubMed2004

Comparison of spirometric reference values.

Lung-function reference values play a vital role in the management of respiratory disorders. There are many proposed reference equations for pediatric spirometry. Recently, spirometric reference equations were proposed, using data from people aged 8-80 years living in the US compiled by the third National Health and Nutrition Examination Survey. Our objective was to compare the predictive value of wider age-range reference equations to established pediatric reference equations for the pediatric population. Spirometry, height, and weight were obtained from 70 normal children aged 6-18 years. The difference between measured and predicted values as suggested by different reference equations was compared. Predicted values from general equations significantly differed from those generated from pediatric equations and from measured values in this population. The difference between measured and predicted values from the wider age-range equations varied between 7-16% for forced expired volume in 1 sec (FEV1) and forced vital capacity (FVC). The difference between measured and predicted values for the pediatric equations varied between 1-4%. Although wider age-range equations provide continuity through age ranges, their predictive accuracy may be low in the pediatric age group, especially for the youngest, smallest children. Extrapolating reference equations beyond the age range of subjects used to generate then is not recommended.

Adolescent↗
PubMedDate not supplied

[Reference values for xenobiotics in biological matrixes: the state of the art].

The basic concepts of reference values of xenobiotics in biological matrixes have been extensively discussed over the last 3-4 years by transferring the principles from clinical chemistry. In this paper three topics of current interest, i.e. the control of variability factors, metanalysis procedure for production of reference values, the reference values as a part of the system of guide values, are dealt with. The control of variability factors is identified as the most important procedure to guarantee the quality and consequently the usefulness of the reference values. Metanalysis is not considered as a correct method to produce reference values, but rather a method to compare the investigation published and to compel the investigators to standardize their working methods. Lastly reference values should be considered as the first step of an integrated system of values (action levels, limit values) which enable us to correctly interpret the significance of biological monitoring.

Alcohol Drinking↗
PubMed1989

[Reference values of ambulatory arterial pressure in activity and during the night. Multicenter study of 394 normotensive subjects at rest].

The blood pressure pattern and variability were assessed in a population of 394 normotensive subjects (OMS) stratified by age (20 to 75 years) and sex. Ambulatory blood pressure measurements were performed with an automatic device (Spacelabs 5200) every 15 min. from 6 a.m. to 12 p.m., and every 30 min. from 0 a.m. to 6 a.m. The analysis was effected during normal daily activities (from 9 a.m. to 7 p.m.) and during night (from 11 p.m. to 7 a.m.). Blood pressure levels were higher in males than females. During daytime and nighttime, diastolic blood pressure rose with age until 59 years while SBP was not affected, except for the females older than 60 years. After this age, diastolic blood pressure decreased. No epidemiological study has provided a measure of the cardiovascular risk related to ambulatory blood pressure, so that we were unable to define true normal values. However, reference population values provided from two statistical methods: limit of the 95th upper confidence interval for the mean of limit of the 90th percentile value for the total data. These blood pressure distributions according to age and sex may allow a better approach to borderline hypertensive patients.

Adult↗
PubMedDate not supplied

[Reference values for the central motor conduction time and silent period obtained by the transcranial magnetic stimulation].

INTRODUCTION: Normal values of reference to transcranial magnetic stimulation for the motor central conduction time (CCT) and silent period (SP) is recorded in 30 healthy control subjects over abductor pollicis brevis. MATERIAL AND METHODS: We get for the CCT four measurements: two with low intensity of stimulus, 5% plus the motor threshold, with and without facilitation (CCT1 and CCT1 fac.); and two with high intensities of stimulus, elevating the magnetic stimulation intensity to 1.5 times the threshold (CCT2 and CCT2 fac.). RESULTS AND CONCLUSIONS: The mean and standard deviation of each measurement are: CCT1: 9.34 +/- 1.19, CCT1 fac.: 7.12 +/- 1.1. CCT2: 8.84 +/- 1.05 and CCT2 fac.: 6.57 +/- 1.05. Given that the CCT and SP doesn't follow a normal distribution, the medium and the 5-95% percentiles for the normal values of reference are calculated; there are: CCT1: 7.15-11.32, CCT1 fac: 5.27-9.42. CCT2: 7.05-10.73 and CCT2 fac: 4.91-9.14. For the silent period gets only one measurement employing high intensities. These last measurement were recorded in two localizations: on vertex and on motor area, selecting the greater duration. Given the great individual variability of this period in normal population absolute and ratio for the difference duration of SP between both sides are calculated. The latency of the SP is 50.2 +/- 5.99, 95 percentiles 39.1-64.63, the duration 151 +/- 32.51, 95 percentiles 102.63-239.55. The total SP measured from the discharge of the stimulus to the end of the silent period is 201.71 +/- 33.27; 95 percentiles: 151.39-296.4. The comparison of both hemispheres would give us pathological security for the 99.99% of the population for more than 14.94 ms of absolute difference, and for less of the 79.81% of ratio difference. A summary of the discoveries of the silent period in different pathologies is contributed in the discussion.

Adult↗
PubMed1987

Neonatal reference values for ionized calcium, phosphate and magnesium. Selection of reference population by optimality criteria.

Thirty-one full-term newborn babies were investigated in order to establish reference values for ionized calcium. Only children fulfilling certain optimality criteria (with best possible maternal and infant conditions and uncomplicated pregnancy and delivery) were included. All infants were breast fed. Capillary blood for analysis of ionized calcium was collected by heel puncture on day 1 (6-36 h post partum, p.p.), day 3 (60-84 h p.p.) and day 5 (108-132 h p.p.). Ionized calcium was measured with a semi-automatic electrode system ICA 1 (Radiometer A/S, Copenhagen, Denmark). The reference ranges (mean +/- 2 SD) for days 1, 3 and 5 were 1.05-1.37, 1.10-1.42 and 1.20-1.48 mmol/l, respectively. The mean ionized calcium concentration on day 1 was significantly lower than on days 3 and 5. Reference values are also given for total calcium, magnesium and phosphate. We emphasize that it is impossible to calculate ionized calcium from total calcium or vice versa.

Calcium↗
PubMedDate not supplied

[Statistical aspects of the definition of reference values].

The criteria adopted in the study of reference values have a great influence on the statistical analysis of the data. To avoid a poor statistical treatment of the data, the scope of the study must be well defined: a study to establish reference values for a chemical in the body fluids of a population is not a survey to prove relations among variables and the chemical. In this latter case, criteria to select subjects and methods are different. Confusion between the two types of surveys can lead to poor results. Reference subjects must be selected with precision, using reproducible criteria. It can be suggested to pick-up subjects from a variety of sub-groups of the population. It must be used selection criteria strictly defined to exclude from the study groups of subjects having specified characteristics (patients, resident in contaminated-zone...). The use of partition criteria is useful to know the distribution of some characteristics in the population, or to describe reference values in particular subgroups. On the contrary, partition can not be used to study relationships. Particular attention must be payed in choosing number of strata and variable of partition. When a population is analysed for reference values, the choice of subjects and relevant variables must be made after consulting a statistician.

Adult↗
PubMed2004

The evolution of the reference value concept.

This manuscript reviews the introduction of the concept of reference values, the corresponding philosophy, and subsequent recommendations reflecting the different subtopics of the field. The generally unrecognised phenomenon that laboratory results of the population tended to be lognormal instead of Gaussian attracted the attention of the author, who became sceptical of the concept of normal values because of its ambiguity. Together with N.-E. Saris a new concept of reference values was launched at a congress in 1969. Briefly, clinical measurements should be interpreted against values from proper control subjects. Subsequently international, regional and national societies established expert panels which produced recommendations covering the general principles and terminology of reference values, the concept of health, standardised specimen collection and preanalytical factors, statistical treatment of collected values, stratification of data, relating observed (patient) values to reference values, etc. The importance of using correct terminology, taking into consideration the aim of ordering the laboratory test and some neglected procedures (e.g., survival values) are emphasised. New developments such as reference changes are mentioned. The field has evolved largely as the result of constructive international teamwork.

Chemistry, Clinical↗
PubMed1995

Finding the "natural" vector bases for multidimensional reference values.

The concept of reference values can be extended to multidimensional results. A probability function describes the relative density of the observations in the multivariate space. When the density of a given point is measured relative to all other points, we get an estimate of the density rank of a given point. If the rank of a point is lower than 95 per cent of all points, the multidimensional result is outside the multidimensional reference range. The single-dimensional case is a special case of this general concept. Many observations are needed to define multidimensional distributions. However, less points are needed if the dimensionality of the data matrix is reduced by statistical methods such as principal component analysis (PCA). Also other vector bases than the orthogonal solution produced by PCA are possible, and all of them compress data equally well. So the choice must be based on other criteria than compression. We propose using a vector basis that consists of positive numbers. The positive vectors can be found by direct methods such as Alternating Regression (AR) or they can be modified from the results of the PCA. Positive vectors resemble the spectra that are familiar in chemistry and physics. They are a "natural" way to describe multidimensional results. It is easier to name the positive vectors than the purely statistical vectors of PCA. To obtain a unique positive solution, additional constraints besides positivity are needed.

Clinical Laboratory Techniques↗
PubMed2002

Basic anatomical and physiological data for use in radiological protection: reference values. A report of age- and gender-related differences in the anatomical and physiological characteristics of reference individuals. ICRP Publication 89.

This report presents detailed information on age- and gender-related differences in the anatomical and physiological characteristics of reference individuals. These reference values provide needed input to prospective dosimetry calculations for radiation protection purposes for both workers and members of the general public. The purpose of this report is to consolidate and unify in one publication, important new information on reference anatomical and physiological values that has become available since Publication 23 was published by the ICRP in 1975. There are two aspects of this work. The first is to revise and extend the information in Publication 23 as appropriate. The second is to provide additional information on individual variation among grossly normal individuals resulting from differences in age, gender, race, or other factors. This publication collects, unifies, and expands the updated ICRP reference values for the purpose of providing a comprehensive and consistent set of age- and gender-specific reference values for anatomical and physiological features of the human body pertinent to radiation dosimetry. The reference values given in this report are based on: (a) anatomical and physiological information not published before by the ICRP; (b) recent ICRP publications containing reference value information; and (c) information in Publication 23 that is still considered valid and appropriate for radiation protection purposes. Moving from the past emphasis on 'Reference Man', the new report presents a series of reference values for both male and female subjects of six different ages: newborn, 1 year, 5 years, 10 years, 15 years, and adult. In selecting reference values, the Commission has used data on Western Europeans and North Americans because these populations have been well studied with respect to antomy, body composition, and physiology. When appropriate, comparisons are made between the chosen reference values and data from several Asian populations. The first section of the report provides summary tables of all the anatomical and physiological parameters given as reference values in this publication. These results give a comprehensive view of reference values for an individual as influenced by age and gender. The second section describes characteristics of dosimetric importance for the embryo and fetus. Information is provided on the development of the total body and the timing of appearance and development of the various organ systems. Reference values are provided on the mass of the total body and selected organs and tissues, as well as a number of physiological parameters. The third section deals with reference values of important anatomical and physiological characteristics of reference individuals from birth to adulthood. This section begins with details on the growth and composition of the total body in males and females. It then describes and quantifies anatomical and physiological characteristics of various organ systems and changes in these characteristics during growth, maturity, and pregnancy. Reference values are specified for characteristics of dosimetric importance. The final section gives a brief summary of the elemental composition of individuals. Focusing on the elements of dosimetric importance, information is presented on the body content of 13 elements: calcium, carbon, chloride, hydrogen, iodine, iron, magnesium, nitrogen, oxygen, potassium, sodium, sulphur, and phosphorus.

Adolescent↗
PubMed1979

Peak expiratory flow rate. Reference values for Swedish children.

Reference values for the peak expiratory flow rate assessed by the Wright-McKerrow peak flow meter have been established for Swedish children. The material consisted of 143 boys and 132 girls. We recommend the sexes be considered together. The equation of the regression line is 72.14 x height3 + 96.12. The coefficient of correlation is 0.93 and the residual standard deviation 13.7%.

Body Height↗