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PubMed1999

Reference values for a homogeneous Ferritin assay and traceability to the 3rd International Recombinant Standard for Ferritin (NIBSC code 94/572).

Reference values for two ferritin assays (Tina-quanta Ferritin, Enzymun, both Roche Diagnostics, Mannheim, Germany) were established (136 males and 139 females). To rule out inflammation as well as iron deficiency in the reference population, subjects with the C-reactive protein concentration < 5 mg/l, and zinc protoporphyrin < 40 micromol/mol heme and the soluble transferrin receptor < 3 mg/l were selected. Taking into account latent iron deficiency as well as hereditary hemochromatosis the 5-95 percentile range was as follows: male, 27-365 microg/l; female, 13-148 microg/l for Tina-quanta and 12-151 microg/l for Enzymun. The Tina-quanta Ferritin assay showed a very good correlation (r > or = 0.990) to Enzymun ferritin, Ferritin Abbott (Abbott Diagnostics, Delkenheim, Germany), N Latex Ferritin (Dade Behring, Marburg, Germany) and the Ferritin Chiron (Chiron Diagnostics, Fernwald, Germany). However, the slopes of the standard principal component method analysis were calculated to be between 1.03 (Enzymun) and 1.41 (N Latex Ferritin). For four assays the median recovery of the 3rd International Recombinant Ferritin Standard (NIBSC 94/572) measured by serial dilution was 89-109%. The N Latex Ferritin assay recovered half of the target values. Because of the good correlation with other assays, a matrix effect is likely. The question arises whether the manufacturers' agreement on the recombinant ferritin standard would harmonize ferritin measurement.

Adult↗

PubMed2004

Study of reference values and biological variation: a necessity and a model for Preventive Medicine Centers.

Laboratory tests were at the origin of the modern approach to the evaluation of the health status in many Preventive Medicine Centers. Guided by the theory of reference values and its applications, years of efforts have been devoted to defining the health status of people, and understanding the biological variation of the population. At the Nancy Center for Preventive Medicine, 40,000 people are invited every year for health examination; many coming with their families. French legislation authorized every citizen to have full health examination every five years. Annually, 600,000 people are seen at 70 centers. The visit includes answering questionnaires, physiological and biological testing modified for age, risks, and social criteria. The process concludes with consultation with a general practitioner. Data accumulated over 30 years have led to the identification of primary factors influencing biological variation of common laboratory tests. For example, body mass index (BMI) has to be considered, in addition to age and gender, for measurement of gamma-glutamyltransferase, alanine aminotransferase, and other analytes. More recently, the familial Stanislas cohort has shown that apolipoprotein E (apoE) genetic polymorphism has to be considered as a factor for variation in some individuals. For example, there was greater than 100% difference in the mean concentration of apoE between epsilon2/epsilon2 and epsilon4/epsilon4 individuals. This example nicely illustrates the relationship between genotype and phenotype. Demonstrating the effects of multiple gene polymorphisms on phenotypes will be a valid approach to predictive laboratory medicine.

Adult↗

PubMed2000

Induced sputum cellularity. Reference values and distribution in normal volunteers.

Sputum induction has recently been proposed as the only direct noninvasive method for measuring airway inflammatory indices. The reference values and the distribution of cells in induced sputum in a control population have not yet been well defined. We therefore evaluated data from a large number of healthy volunteers. One hundred fourteen healthy, nonatopic, nonsmoking volunteers without airway hyperreactivity were enrolled (age: 38 +/- 13 yr [mean +/- SD]; FEV(1): 105 +/- 10% predicted; provocative dose of methacholine inducing a 20% decrease FEV(1) > 3,200 microgram). Ninety-six subjects (84%) produced adequate analysis samples. The subjects had a normal age distribution. Their induced sputum was rich in macrophages (69.2 +/- 13%) and neutrophils (27.3 +/- 13%), and poor in eosinophils (0.6 +/- 0.8%), lymphocytes (1.0 +/- 1.2%), and epithelial cells (1.5 +/- 1.8%). Only macrophages and neutrophils showed a normal distribution; total and differential counts of other cells did not. We propose that these data be used in comparison of the induced sputum cells of normal subjects and those of patients with airway inflammation.

Adult↗

PubMed2000

Reference values for chromium, nickel and vanadium in urine of youngsters from the urban area of Rome.

In the assessment of human health risk, the obtainment of reference values in biological tissues and/or fluids is crucial to estimate the type and magnitude of occupational and environmental exposure. In this context, urine is the major excretion route for many noxious substances that have entered the organism and can be viewed as one of the most useful materials for biomonitoring campaigns. In this study, reference concentration ranges for Cr, Ni and V in urine were achieved in a sub-population of 131 youngsters, aged 6-10, attending primary schools in the urban area of Rome. Subjects under drug therapy or affected by any pathological diseases were not included in this investigation. Strict precautions against contamination or loss of the analytes of interest were adopted for all steps. Determinations were performed by means of high resolution inductively coupled plasma mass spectrometry. In general, the natural log-transformed concentration data for the three elements investigated conformed to a satisfactorily normal distribution. The estimated reference ranges were as follows (microg g(-1) creatinine): Cr, 0.07-0.76; Ni, 0.20-1.23; V, 0.02-0.22. The sex of the youngsters was tentatively treated as a statistical explanatory variable using the Fischer F-test on variance.

Child↗

PubMed2005

Sural/radial nerve amplitude ratio: reference values in healthy subjects.

The sural/radial nerve amplitude ratio (SRAR) has been proposed as a sensitive indicator of early-stage axonal polyneuropathy. However, previous studies did not take into account the effect of sex differences or different calculating methods. To obtain reference values and information on the variability of the SRAR in daily practice, we measured amplitudes of sural and superficial radial sensory nerve action potentials in 106 healthy adults, correlated them with epidemiological variables, and calculated the SRAR in several ways. Our results show that the SRAR is a robust measure, independent of age, weight, sex, or method of calculation. The use of bilateral measurements is recommended. The cut-off value (5th percentile) of 0.2 in these healthy subjects is much lower than found previously, especially compared to defining cut-off values by comparing patients with matched controls. Further study is needed to establish the clinical value of this SRAR in the early detection of axonal polyneuropathies.

Action Potentials↗

PubMed1989

Automatic analysis of heart rate variation: I. Method and reference values in healthy controls.

Many patients referred to an electrophysiological laboratory may have autonomic dysfunction. Some parasympathetic tests are based on the assessment of heart rate variation induced by breathing, Valsalva maneuver, and standing. We have developed fast and practical computer-based methods to analyze heart rate variation using standard EMG equipment and a personal computer. For quantitative description we have evaluated different algorithms, both earlier described and new ones. Findings in patients with diabetes have been compared with those obtained from healthy subjects in order to determine the diagnostic utility of the various algorithms. The optimal algorithm has been chosen by this and other criteria, and a reference database from healthy subjects has been developed.

Adolescent↗

PubMed1986

Electroneurographic examination of the ulnar and radial nerves in the dog: reference values, biological variation and reproducibility.

The radial and ulnar nerves were examined electrophysiologically in 90 normal dogs. In 66 of these dogs, aged between one and eight years, the reference values were established for 27 variables. Multicomponent sensory nerve action potentials were encountered at the proximal recording site in the ulnar nerve in 68 per cent of the dogs in the reference group and in the radial nerve in 26 per cent. Differences between the sexes were not significant, nor were differences between two breeds of similar body size. There were no significant age related differences between the ages of one and eight years. Limb length, measured as the distance between sensory stimulation site (digits) and proximal recording site (elbow), was found to have a significant effect on the velocity, amplitude, number of positive peaks and duration of the nerve action potentials. The variation in results of repeated measurements of velocities ranged from 0 to 11 per cent. The relative error in velocities due to errors in measurement of distance and latency ranged from 1 to 12 per cent.

Age Factors↗

PubMed1999

Reference values for concentric knee isokinetic strength and power in nonathletic men and women from 20 to 80 years old.

STUDY DESIGN: A prospective, controlled, randomized study. OBJECTIVE: To establish reference values for prediction of concentric isokinetic knee strength and power in a sample of nonathletic men and women. BACKGROUND: Adequate interpretation of knee isokinetic strength and power relies on a representative frame of reference. However, none of the most widely cited prediction studies used a randomly selected sample of nonathletic subjects, therefore limiting the clinical application of these studies. METHODS AND MEASURES: We evaluated the concentric right and left knee extensor and flexor peak torque, total work, set total work, average power, and torque acceleration energy (Cybex 6000 System) in 96 healthy subjects (45 men and 51 women, aged 20 to 80), randomly selected from more than 8000 individuals. RESULTS: By stepwise regression analysis, we found that gender, age, weight, height, and regular physical activity explained up to 84% of the variability of the dependent variables: a set of linear prediction equations for strength (at 60 degrees/s) and power (at 300 degrees/s) is provided. CONCLUSIONS: Results from this study might provide a clinically useful frame of reference for interpretation of concentric isokinetic knee strength and power in nonathletic men and women.

Adult↗

PubMed2005

Reference values of coplanar and non-coplanar PCBs in serum samples from two Italian population groups.

The main goal of this study is to establish the reference values of individual Polychlorinated biphenyl (PCB) congeners in non-occupationally exposed subjects. Since the PCB pattern in human serum is related to the living area, two different population groups from North and Central Italy, were compared. Serum concentrations of both coplanar and non-coplanar PCB congeners were measured by using gas chromatography coupled with low-resolution mass spectrometry (HRGC-LRMS). A fast and reliable method for the determination of 60 congeners had been previously validated. Its reliability was further verified by using high-resolution mass spectrometry. Thirty-one congeners out of 60 were found at detectable concentrations in at least one sample. The mean value for total PCBs was found to be 2.48 and 3.93 microg/L for the two population groups. Eight dioxin-like PCBs were detected. In accordance with the findings from the literature, the most abundant congeners were found to be 153, 138, 180, and 170. Both univariate and multivariate analysis showed that age is a significant determinant of PCB concentrations. The correlation increased with increasing chlorination. Slight differences in the PCB pattern were observed in the two population groups.

Adult↗

PubMedDate not supplied

Reference values of umbilical cord and third-day cystatin C levels for determining glomerular filtration rates in newborns.

The aim of this study was to determine reference values for serum cystatin C at, and 3 days after, birth, and to determine if the concentration was influenced by gender, gestational age or bilirubin level. Umbilical cord and peripheral venous blood was taken, and serum cystatin C, creatinine, and total and direct bilirubin levels were measured. The mean concentration of cystatin C was not significantly different between cord blood and blood taken on day 3 (1.36 +/- 0.35 mg/l and 1.35 +/- 0.33 mg/l, respectively). Comparison of subgroups, divided by gender, duration of gestation and bilirubin levels, using the Mann-Whitney U-test and Wilcoxon analysis, showed no effect of these parameters on cystatin C levels.

Bilirubin↗

PubMed1990

Blood cell filtrability: reference values and clinical applications.

In 500 healthy individuals cell deformability, expressed as cell filtration rate in microliters/s was studied with a microcirculation method in order to determine reference values for this method for various age groups in adults. The overall normal red cell filtration rate (RFR) value in healthy individuals was 69 +/- 11 microliters/s. When one compared the age groups 20-29 and 60-69 years, the reductions for RFR, white cell filtration rate (WFR), plasma-white cell filtration rate (P-WFR) and whole-blood filtration RATE (WBFR) was 26 +/- 3 (p less than 0.01), 32% +/- 5 (p less than 0.01), 28% +/- 4 (p less than 0.01) and 28% +/- (p less than 0.01) respectively. The reduction of RFR was graded into four clinical classes (GCTA = Gothenburg Cardio-Thoracic Association); I = 1-24%, II = 25-49%, III = 50-74%, IV = 75-100%, class I with lowest and class IV with highest reductions. Significant reductions in the mean RFR were noted in patients undergoing heart surgery (36% +/- 3, P less than 0.01, class II), patients with cardiac arrest (55% +/- 5, p less than 0.01, class III), occlusive arterial disease (58% +/- 6, p less than 0.001, class III) diabetes (45% +/- 5, p less than 0.01, class II). None of the patients had a normal RFR value. This study demonstrated a loss of cell deformability with age and disease.

Adult↗

PubMed1991

Suggested reference values for regional blood volumes in humans.

Estimates of regional blood volumes (BVs) in man are needed for the dosimetry of radionuclides that decay in the circulation to a significant extent. The tabulation of regional BVs in Publication No. 23 of the International Commission on Radiological Protection (ICRP Reference Man document) may be the best available for dosimetric applications but is not consistent with current information for some organs and does not address some important blood pools. The purpose of this paper is to suggest an improved set of reference values for regional BVs in adult humans. The total blood volume (TBV) is viewed as comprising 22 separate pools, including several pools not addressed in the ICRP Reference Man document. Values suggested here for brain, liver, skin, active marrow, inactive marrow, and bone differ by at least a factor of two from those given for ICRP Reference Man.

Adult↗

PubMed1994

[Reference values of anthropometry parameters in school children and youths in Subotica].

Anthropometric measurements are most often used in order to evaluate the state of nourishment and gain insight into body growth and development of children and young people. The use of different criteria in everyday practical work causes very diversified results and at the same time presents a problem in early detection of certain disorders of growth, development and state of nourishment and in undertaking adequate dietetic and therapeutic treatments. In Subotica 18864 persons from 8-19 years of age were examined by transverse anthropometric measurements of height and weight. By statistical processing of results mean values, medians and percentiles of body height, body mass and the body mass index, BMI (kg/m2) were established. These reference values present a base for producing nomogram of growth, development and state of nourishment in children and young people in our area which could be applied in everyday work at clinics.

Adolescent↗

PubMedDate not supplied

[Aromatic amines with certain, probable, or possible carcinogenic action: reference values].

The aim of this work is to determine the amount of some aromatic amines in urine of non-exposed people in order to define a reference value. The literature examination has showed that only a small numbers of aromatic amines are usually determined in urine namely: aniline, benzidine, 2-naphtilamine, o-toluidine, 3,3'-dichlorobenzidine, 4-chloro-o-toluidine and 4-chlorobenzidine. On the basis of our experience the analytical method proposed by Lichtenstein is appropriate for obtaining reliable analytical results.

Amines↗

PubMed1992

Tentative reference values for gold, silver and platinum: literature data analysis.

Data available on biologic fluid content of therapeutic metals are uneven for silver, gold and platinum respectively. Tentative reference values may be proposed on the basis of the most representative studies for silver and gold. For silver it is suggested that the variability in normal subjects could range up to 10 micrograms/l in whole blood and up to 1 microgram/l in urine. For gold 0.5 microgram/l can be considered the upper limit for both whole blood and urine. For platinum there is no indication that concentration in either blood or urine could reach detectable amounts in normal subjects.

Body Fluids↗

PubMed2003

A survey of 14 computed tomography scanners in Greece and 32 scanners in Italy. Examination frequencies, dose reference values, effective doses and doses to organs.

A survey of examination frequencies, dose reference values, effective doses and doses to organs involving 14 scanners from Greece and 32 scanners from Italy was carried out for the years 1999 and 2000. Examination frequencies per scanner and per year were found to be 3590 for Greece and 4520 for Italy. For the types of examinations considered, CDTI(W) and DLP measurements were taken. Also scan lengths used for the same types of examinations were monitored. For the same types of examinations effective doses were calculated by two methods, and it was found that their mean values ranged from 13.1 mSv for thoracic spine to 1.6 mSv for the brain examinations. From the data of the 14 Greek laboratories, doses to organs were calculated and it was found that the thyroid receives 50.2 +/- 19.8 mGy during a cervical spine examination while the gonads receive 17.8 +/- 6.9 mGy during a routine pelvis examination.

Body Burden↗

PubMed1998

Left ventricular diastolic function in infants, children, and adolescents. Reference values and analysis of morphologic and physiologic determinants of echocardiographic Doppler flow signals during growth and maturation.

OBJECTIVES: The aim of this study was to set up reference values for Doppler flow-derived left ventricular filling parameters and to evaluate physiologic determinants of changes in signal expression related to maturation. BACKGROUND: In left ventricular diastolic function studies, age-related modulations in signal expression are observed. Assuming degenerative myocardial changes to be absent during childhood and adolescence, the determinants of these modulations must be different from those suspected in adults. METHODS: Pulsed wave Doppler signals from the mitral valve tip region were recorded in 329 healthy subjects aged 2 months to 39 years. Multiple linear regression was used to evaluate statistical relations between Doppler flow signals and stroke volume in the mitral valve area. RESULTS: Increasing early filling time velocity integral throughout maturation caused a decrease in atrial filling fraction from 0.34+/-0.06 to 0.24+/-0.04 (p < 0.005). Peak flow velocities during atrial systole decreased from infancy to adolescence (66+/-15 to 41+/-10 cm/s). Main effects on signal modulation were caused by heart rate, stroke volume and mitral ring area with a linear model fit (R2) of 0.79 for early filling phase (E)-time velocity integral, 0.6 for atrial filling phase peak velocity 0.84 for total E duration and 0.73 for E deceleration time. Atrial filling phase-time velocity integral, albeit significantly dependent on heart rate, was stable throughout growth. CONCLUSIONS: During infancy and childhood, the stroke volume crossing the mitral valve is a main modulator for early filling phase (E)-time velocity integral and diastolic time intervals during early filling, whereas atrial filling phase parameters are mainly dependent on heart rate. This results in a more pronounced atrial filling during infancy and childhood.

Adolescent↗

PubMed1981

[Antithrombin III: reference values found with a chromogenic substrate (chromozym TH) (author's transl)].

A new kinetic assay for antithrombin III (heparin-cofactor) in plasma was used to determine reference values. Ranges of 10--15 IU/ml at 25 degrees C and 20--29 IU/ml at 37 degrees C were found for a reference population of 219 men and 204 women 15--93 years of age. There was no evidence that these values vary with age or sex, nor was there any difference between pre- and postprandial antithrombin activities, or between smokers' and non-smokers' values. None of the illnesses present in the reference population nor any related drug therapy affected the antithrombin III level, and there was no statistically significant difference between the values for women taking oral contraceptives and those who did not. However, this latter observation does not preclude the possibility of individual variation.

Adolescent↗