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PubMed1996

[Detection of prostate cancer in urological practice: clinical establishment of serum PSA reference values by age].

BACKGROUND: Determinations of serum levels of prostate specific antigen (PSA) are widely used for the detection of prostate cancer, but have not demonstrated sufficient sensitivity and specificity to be useful in urological practice. In order to enhance the diagnostic value of serum PSA, we studied the distribution of serum PSA levels by age in urological patients without clinical evidence of prostate cancer and determined clinical PSA reference values by age decades. METHODS: The study included a total of 590 male patients aged 40 to 89 years who visited our urological clinic complaining of voiding symptoms from January 1991 to October 1994, but had no clinically evident prostate cancer. We defined patients to be without clinical evidence of prostate cancer if they had negative test results in digital rectal examination, ultrasonography, and serum PSA assay, or had positive test results in one or more of these tests but had a nonmalignant prostate biopsy. Serum PSA levels were measured by E-Test Tosoh II (AIA-PACK PA, normal range; 0 to 5.3 ng/ml). The patients were grouped by age decades and serum PSA values were given as percentiles. RESULTS: Analyzed by Pearson's correlation coefficient, serum PSA levels were correlated significantly with patient age (r = 0.24, p < 0.001). Prostatic volume was correlated weakly but significantly with patient age (r = 0.12, p = 0.005), and PSA density was also correlated significantly with patient age (r = 0.20, p < 0.001). Thus, serum PSA levels were demonstrated to increase with advancing patient age. Factors other than benign prostatic hypertrophy were also suggested to explain the increase in serum PSA levels in older patients. With the 95th percentile for serum PSA as the upper limit, the clinical PSA reference values by age decades were determined to be 2.6 ng/ml for patients aged 40 to 49 years, 5.0 ng/ml for 50 to 59 years, 7.5 ng/ml for 60 to 69 years, 10.1 ng/ml for 70 to 79 years, and 12.4 ng/ml for 80 to 89 years. CONCLUSION: We found a significant increase in serum PSA levels with advancing patient age. Thus, it is appropriate to have serum PSA reference values by age decades. Prospective clinical trials are necessary to define the usefulness of the PSA reference values by patient age in urological practice.

Adult↗

PubMed1991

Cardiovascular autonomic reflex tests: normal responses and age-related reference values.

One hundred and forty-three healthy unmedicated subjects from a random sample, aged 20-80 years, were examined and cardiovascular autonomic function tests (Valsalva manoeuvre, deep and quiet breathing tests and active orthostatic test) were performed in order to study normal responses to these tests and to determine age-related reference values. Most of the cardiovascular indices reflecting autonomically mediated heart rate responses decline with advancing age and this leads inevitably to the need for age-related reference values. The indices are in general independent of sex but most indices are dependent on resting heart rate. The inter-individual variation is very marked so that the normal ranges are wide, and because the indices diminish with age, the lower reference values are less suitable for use in aged subjects. The reference values make it possible to use the indices for diagnostic purposes in young and middle-aged subjects (up to 65 years), whereas in older subjects the indices can be used in order to exclude autonomic disturbances. Reproducibility of heart rate indices is satisfactory or good whereas reproducibility of blood pressure indices is poor.

Adult↗

PubMed2004

Population-based hematologic and immunologic reference values for a healthy Ugandan population.

To assess the validity of the reference values for hematologic and immunologic indices currently used in Africa, we evaluated blood samples from 3,311 human immunodeficiency virus (HIV)-negative Ugandans aged 1 week to 92 years. Erythrocyte, hemoglobin, and hematocrit levels and mean corpuscular volume all significantly increased with age (P < 0.001) and were independent of gender until the age of 13 years, after which the levels were higher in males than in females (P < 0.001). White blood cell, neutrophil, lymphocyte, basophil, and monocyte counts significantly declined with age until the age of 13 years (P < 0.001), with no differences by gender, while platelet counts declined with age (P < 0.001) and showed differences by gender only among adults older than age 24 years. CD4+- and CD8+-cell counts declined with age until the age of 18 years; thereafter, females had higher counts than males. The absolute values for many of these parameters differed from those reported for populations outside Africa, suggesting that it may be necessary to develop tables of reference values for hematologic and immunologic indices specific for the African population. This may be particularly important with regard to CD4+-cell counts among children because significant differences in absolute and percent CD4+-cell counts exist between the values for Western populations and the values for the population evaluated in our study. These differences could influence the decision to initiate antiretroviral therapy among children infected with HIV.

Adolescent↗

PubMedDate not supplied

Reference values of urinary acetone in a Brazilian population and influence of gender, age, smoking and drinking.

BACKGROUND: Reference values for some xenobiotics naturally present in the body are important for biomonitoring, in order to compare the levels found in a population exposed to the xenobiotic with those of a reference population. Acetone in urine (UAc) is the most used bioindicator to evaluate worker exposure to acetone and isopropanol. OBJECTIVES: Since acetone is also found in individuals not occupationally exposed to these solvents, the purpose of the present study was to evaluate the basal levels of UAc and the possible influence of individual factors on such levels. METHODS: The population consisted in 207 individuals, 91 men and 116 women, between 18 and 80 years old. UAc was determined by headspace/gas chromatography/FID. RESULTS: For the total population, the reference values found were: mean (+/- SD), 1.12 (+/- 0.47) mg/l; median 1.04 mg/l; geometric mean 1.03 mg/l; 95% confidence interval 0.98-1.26 mg/l, 95th percentile 2.20 mg/l and upper reference level (mean+2 SD) 2.06 mg/l. As the values of UAc resulted in a non-Gaussian distribution, the option was to transform these values to log UAc, which drew the data closer to normal distribution (W=0. 98532, p<0.7000). CONCLUSIONS: Reference values for acetone in urine determined in a population in south Minas Gerais, Brazil, are close to the background values reported elsewhere; gender and ingestion of alcohol seem to affect the basal levels of urinary acetone, while age or smoking showed no similar effect.

Acetone↗

PubMed2000

Reference values and methods comparison of a new testosterone assay on the AxSYM system.

OBJECTIVES: We have contributed to the Design Validation Protocol of the new Abbott AxSYM Testosterone assay with a study on reference values and methods comparison. DESIGN AND METHODS: For reference values a population of 45 women and 30 men was tested. In methods comparison, 132 samples for the AxSYM vs. ACS-180, and 30 for the AxSYM vs. Elecsys were used. Pearson and intraclass concordance coefficients and Passing-Bablock test were performed for overall group, men and women. RESULTS: Reference values were 0.9-3.1 (females) and 1.0-30.2 nmol/L (males). Globally, a good agreement between methods in both the AxSYM vs. ACS-180 (slope: 0.88, y-intercept: 0.67, r = 0.961) and the AxSYM vs. Elecsys (slope: 1.08, y-intercept: 0.31, r = 0.935) studies was found. Slightly worse results were observed for women. CONCLUSIONS: The reference range of testosterone by the AxSYM system matches with those published for other methods. An acceptable agreement between the AxSYM Testosterone assay and both a classical (ACS-180) and a more recent (Elecsys) methodology was observed.

Adolescent↗

PubMed1987

Highly sensitive assays of serum-thyrotropin in the diagnosis of hyperthyroidism: assessment of performance and reference values.

The performance of three different highly sensitive immuno-assays for thyrotropin in serum (S-TSH) was compared. Specimens from 803 patients with suspected hyperthroidism or other thyroid disease were used. Hyperthyroid patients were identified and characterized by determining serum thyroid hormones and by clinical observation. The performance of the methods in discriminating between hyperthyroidism and euthyroidism was described in terms of diagnostic sensitivity and specificity. The performance was also assessed by systematically varying the reference values. If patients with treated hyperthroidism were eliminated, the three S-TSH assays performed equally well at a suggested lower reference value of 0.4 mU/l. A diagnostic efficiency of more than 0.95 was achieved at the observed prevalence of disease (0.12). A graphical model which allows an adjustment of reference values to favour sensitivity or specificity is presented. Reference values were also calculated from the euthyroid subjects using parametric and non-parametric approaches. The specificity, when using the recommended discrimination level, suggests that patients with low S-TSH values should be subjected to further investigation by biochemical or other methods.

Adolescent↗

PubMedDate not supplied

[Reference values in occupational and environmental medicine].

Origin, significance, production and use of reference values (RV) in environmental and occupational medicine are discussed. The concept of RV was established in last sixties to correctly interpret data from modern clinical chemistry, but its acceptance in occupational medicine was neither immediate nor easy. These difficulties were mainly due to the nature and biological fate of analytes for which RV were requested, quite different from those of clinical chemistry. For this reason specific procedures to select the subjects, to control the pre analytical factors and to set up analytical methods are necessary. The Italian Society of Reference Values (SIVR) attempted to achieve concepts and practice for RVs and proposed RVs produced by specific investigations for some metals and organic compounds. Furthermore in this paper two provisional lists of RVs for metals and organic substances are proposed. Finally the relationship between RVs and other more familiar guide line values such as action levels and limit values is discussed.

Environmental Medicine↗

PubMed1999

Methanol reference values in urine from inhabitants of Brazil.

In order to properly evaluate the results of the occupational biomonitoring of chemicals it is necessary to establish reference values for the biomarkers of exposure. The aim of this study was to determine the reference values for methanol in urine of the general population non-occupationally exposed to the xenobiotic under study. Thus, urinary methanol was measured in 84 occupationally non-exposed subjects from the city of São Paulo, Brazil, by means of headspace gas chromatography with a flame ionization detector. The results revealed a mean of 2.26 +/- 1.26 mg methanol/l urine and a geometric mean of 2.10 mg/l for the studied population. The reference values varied within the range of 0.50-4.78 mg/l (mean +/- 2 S.D.). Methanol levels in urine did not differ statistically between male and female subjects. Urinary methanol in the total population was less than 4.80 mg/l in 95% of cases.

Adult↗

PubMedDate not supplied

[Reference values of urinary mercury in the Italian population].

This paper shows the results of a polycentric study performed to assess the reference values of urinary mercury (U-Hg) in Italian population. 374 subjects from four Italian cities (Bari, Brescia, Genova e Siena) have been examined. A questionnaire on life style, dietary habits, occupational or environmental exposure to Hg and clinical history has been administered to every participant and number and surface of dental amalgams have been verified for all subjects. The determination of U-Hg has been performed on urinary extemporary samples by hydride generation atomic absorption method (HG-AAS); urinary creatinine has been determinated to reduce the intraindividual variability. U-Hg reference values were: 0.21-3.20 micrograms/g creat (5 degrees and 95 degrees percentile) and 0.12-6.04 micrograms/g creat (range). Moreover study results have shown that number and surface of dental amalgams, dietary fish intake and body mass index (BMI) influenced significatively U-Hg excretion. U-Hg reference values from this polycentric study resulted comparable to those assessed in other European countries, whereas the mean U-Hg observed in the referent Italian population was lower.

Adolescent↗

PubMed1999

Reference values and action levels of biological monitoring in occupational exposure.

The primary objectives of biological monitoring are (1) to prevent health impairment, (2) to assist in the assessment of risk, and (3) to evaluate the effectiveness of environmental controls. An efficient way to achieve these objectives would be to enforce the compliance of biological exposure standards at the workplace. However, biological monitoring should be viewed in the total context of control and prevention of work-related diseases, and not merely to comply with permissible standards. Biological monitoring depends very much on the conditions that the chemical is absorbed and how it is metabolised. Genetic diversity could therefore contribute to significant differences in this aspect. Furthermore, many of the reference values established have so far not been fully validated and therefore their usefulness is rather limited. This paper reviews and illustrates using some recent findings to show that biological reference values are influenced not just by the above mentioned issues, but also factors such as (1) health and nutritional status of the exposed population, (2) social and cultural factors, and (3) climatic conditions. Caution has to be taken when considering having an action level for some of the biological reference value. Biological reference values set without considering people, technology, and working conditions would be fraught with difficulties in implementation.

Benzene↗

PubMed2001

Intra- and inter-tester reliability and reference values for hand strength.

The intra- and inter-tester reliability for measurement of handgrip strength and indexgrip strength using the Jamar dynamometer was investigated in 32 healthy volunteers, and the intra-tester reliability in 13 patients with cervical radiculopathy. The results from the reliability studies showed that handgrip and indexgrip strength measured with the Jamar dynamometer is a reliable method (ICC values 0.85-0.98) and can be recommended for use in clinical practice. Age- and sex-specific reference values for handgrip strength and indexgrip strength were measured with the Jamar dynamometer in 101 randomly selected healthy volunteers, aged 25-64 years. The results from the reference value study showed that sex is a more important determinant of hand strength than age, height and body weight. The reference values for hand strength improve the potential for objective evaluation of patients with arm/hand disorders caused by cervical radiculopathy.

Adult↗

PubMed2001

Multicentric reference values for some quantities measured with Tina-Quant reagents systems and RD/Hitachi analysers.

Ten clinical laboratories in different regions of Spain have shared the search for reference individuals and the production of reference values for quantities concerning ferritin, transferrin, rheumatoid factors, C-reactive protein and antistreptolysin O, using Tina-Quant reagents systems and RD/Hitachi analysers. All the logistic work has been done in co-operation with the supplier of the reagents and analysers (Roche Diagnostics España, S.L., Barcelona). The reference limits produced in the virtual laboratory are derived from the blend of reference values obtained by each laboratory. The multicentric reference limits were estimated according to the recommendations of the International Federation of Clinical Chemistry. The work done is a model of co-operation between the in vitro diagnostic industry and clinical laboratories for the production of reference values.

Adult↗

PubMedDate not supplied

[Reference values of assayable pyridinolines as markers of bone turn-over].

The authors aimed to identify reference values for pyridine cross-links (HP and LP) in clinically normal populations. These cross-links are thought to be markers of bone resorption and are released by osteoclasts and eliminated in the urine. The normal values reported in the literature vary considerably. For this purpose the authors analysed groups of male and female patients, divided into age brackets, with no apparent bone metabolism disorders. Hydroxylysylpyridinoline (HP) values revealed no statistically significant differences in relation to either sex or age. Lysylpyridinoline (LP) values in subjects aged under 50 showed virtually comparable reference intervals in male and female subjects, whereas patients over 50 showed a different pattern of behaviour. In conclusion it can be said that, once reliable reference values have been identified using a urinary cross-link assay (in particular for LP), it is possible to evaluate bone resorption in postmenopausal women.

Age Factors↗

PubMed1992

Definition of reference values for Cd-B and Cd-U: methodological aspects and preliminary results.

In the present study, a definition of the reference values of blood cadmium (Cd-B) and urinary cadmium (Cd-U) was attempted, adopting the same methodology as that used for Hg-B by ICOH and IUPAC. Papers published from 1976 onwards were reviewed. The majority of the studies were concerned with the formation of control groups for toxicological and epidemiological investigations rather than with the definition of reference values. Since the number of subjects for whom data on cadmium were available was small, only the data on Cd-B were considered. After evaluation, only four studies were found to be suitable for the establishment of tentative reference values for Cd-B. It is essential in all such studies to check the statistical and analytical methods for correctness, and the case-list must be selected taking smoking into account as the main interfering factor. It was found that Cd-B values show less dispersion when geometric means and standard geometric deviations are used instead of arithmetic means and standard deviations.

Cadmium↗

PubMed1996

Immunoglobulin M in cerebrospinal fluid: reference values derived from 111 healthy individuals 18-88 years of age.

The importance of immunoglobulin M (IgM) determination in cerebrospinal fluid (CSF) has increased parallel to the need for early diagnosis of infectious and inflammatory disorders of the central nervous system. Current reference values are based on analysis of CSF from 'reference groups' consisting of patients with psychiatric and/or neurological symptoms but without positive clinical findings. Therefore, accurate reference values for CSF IgM are of utmost importance. The present study presents reference values for IgM in CSF in a large sample (n = 111) of healthy individuals with an age span of 18-88 years. The upper reference limit, calculated as the 0.95 fractile, was 0.36 mg/l for CSF IgM, 0.40 for CSF/serum IgM ratio, and 0.045 for the IgM index. These parameters showed no significant difference between sexes nor any significant correlations with age. The correlations between CSF/serum albumin ratio and CSF/S IgM ratio were linear and statistically highly significant, suggesting that the IgM index values do not depend on the blood-CSF barrier function within the normal range of the CSF/serum albumin ratio.

Adolescent↗

PubMed2006

Reference values of total serum IgE and their significance in the diagnosis of allergy in young European adults.

Allergic sensitization mediated by immunoglobulin E (IgE) is the basis of allergic diseases, and elevated total IgE, in spite of some well-known limitations, is frequently included as a diagnostic criterion for allergic diseases. The reference value of total IgE (IgE-t) in the literature (1.5-144 kU/l) was established almost 2 decades ago. The aim of this study was to establish IgE-t reference values, establishing an updated cutoff value able to identify atopic subjects, defined as a positive CAP-radioallergosorbent test to at least one of a panel of common allergens, among young European adults. The study included 6,670 subjects from 10 Western European countries within the framework of the European Community Respiratory Health Survey II. IgE-t and specific IgE (IgE-s) were measured for the main inhalant allergens; IgE-s in class 0 for all allergens (66.2%) characterized non-atopy. The reference values were estimated by means of linear regression using a 50% random subsample of non-atopic subjects. Two non-atopic subsamples were examined so that one subsample could be used to establish reference IgE-t values, and these values were compared to those in the second non-atopic subsample to validate the findings. Sensitivity and specificity for atopy were assessed on the other 50% of non-atopic and on all atopic subjects. The 95th percentile of IgE-t reference values in non-smokers was 148 kU/l in women and 169 kU/l in men, while it was 194 and 220 kU/l in female and male smokers, respectively: serum IgE-t above the 95th percentile identifies <32% and above the 99th percentile <20% of atopic adults (low sensitivity), but a serum IgE-t below the 95th percentile identifies >90% and below the 99th percentile identifies >95% of non-atopic adults (good specificity). Due to the adequate specificity, IgE-t values exceeding the normal limits confirm a suspected atopic status; however, because of the low sensitivity, values below the cutoff seem not to exclude an atopic status with sufficient accuracy.

Adult↗

PubMed1994

[Lung function reference values for students 6 to 16 years of age].

The diagnosis of lung function impairments in childhood is based on a variety of reference values. The assessment of "normal" function and growth of lung and airways in pediatric and environmental investigations is biased. The detection of small airway disease at an early stage is based on flow volume measurements, however, reference values in Europe relied on small and highly selected groups of children. We examined 18,106 children and adolescents aged 6 to 16 years at their schools by standardized methods. After exclusion of children with poor cooperation, respiratory signs or symptoms and active smokers, regression analysis was applied for FVC, FEV1, PEF, MEF75, MEF50, MEF25, and MMEF predicted from standing height, sex, age and weight. Means and standard deviations (SD) of lung function parameters of healthy Austrian school children are presented as a basis for reference. Individual lung function can thus be evaluated in SD-scores. Flow measures representing small airway functions were found higher in adolescent girls. MEF25 showed the highest variability unexplained by anthropometric characteristics. The new reference values improve available tools for early detection of respiratory diseases and dysfunctions in children and adolescents and they should help to evaluate environmental and other factors influencing function and growth of lung and airways.

Adolescent↗

PubMed1992

[Establishment of reference values for fructosamine and HbA1c in childhood].

Reference values for fructosamine and glycated haemoglobin in children are still lacking. Using samples from 522 children (age range 1 day to 9 years), plasma electrophoresis was performed, fructosamine and total protein were determined in EDTA-plasma, and glucose and the fraction of glycated haemoglobin (HbA1c) were determined in EDTA blood. The results were grouped according to age (1, 3 and 5 days, 6-28 days, 2-12 months, 2-3 years, 4-6 years, and 7-9 years). Differences between the age groups were determined using the Mann-Whitney-U-test, and the values in each group were summarized where possible. The 95%-interval was calculated for fructosamine, protein-corrected fructosamine, and HbA1c.

Child↗