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PubMedDate not supplied

Using reference values in pulmonary ventilation studies.

The aim of this study was to examine the discriminating power of six widely used, or recently introduced, reference values in the interpretation of pulmonary ventilation (FVC and FEV1) in occupational health surveys. These six reference values were applied to a sample of 400 Italian males; 200 of the sample were foundry workers and the other 200 were workers who were not occupationally exposed to dusts; 50% of each group were smokers. The relationship between the reference values and their capacity to discriminate between the workers occupationally exposed to dusts and the workers who smoked in each group was evaluated. The results showed very significant differences among the various reference values. Generally speaking these differences may be determined by the different selection criteria of the subjects under study, or may be a result of the different characteristics of the population included in the various studies. Our conclusions show the need for a critical approach to the use of reference values, particularly during screening tests.

Adult↗

PubMed1999

[Reference values for IGF-I, IGFBP-1, IGFBP-3 and osteocalcin in healthy children in Zaragoza].

OBJECTIVE: Our aim was to estimate reference values for basal serum concentrations of insulin-like growth factor (IGF)-I, IGF binding protein (IGFBP)-1, IGFBP-3 and osteocalcin in healthy children of Zaragoza. PATIENTS AND METHODS: The reference population consisted of healthy children between 0 and 14 years of age with normal weight and height and living in the metropolitan area of Zaragoza (Spain). It was a transversal study. Immunoradiometric assays were used to determine basal serum IGF-I, IGFBP-1, IGFBP-3 and osteocalcin concentrations. Reference values and ranges were estimated according to the recommendations of the International Federation of Clinical Chemistry. RESULTS: Reference values have been classified according to age, sex and pubertal stage. IGF-I, IGFBP-1, IGFBP-3 and osteocalcin concentrations differ during the pubertal period according to age. There are differences in IGF-I, IGFBP-3 and osteocalcin levels between prepuberty and puberty and differences in IGF-I and osteocalcin levels among the pubertal stages. Sex did not influence IGF-I or IGFBP-1 concentrations and there were punctual differences in IGFBP-3 and osteocalcin levels between girls and boys. CONCLUSIONS: Sincere there are differences in IGF-I, IGFBP-1, IGFBP-3 and osteocalcin reference values according to age, sex, pubertal stage and immunoassays, it is necessary to establish the reference values for each population and laboratory in accordance with these parameters.

Adolescent↗

PubMedDate not supplied

Hematologic and clinical chemistry reference values in red lories (Eos spp.).

We established reference ranges for three hematologic and 15 clinical chemistry parameters of 40 clinically healthy birds of the genus Eos. The following species were included to the study: Eos histrio (n = 19), Eos squamata (n = 8), Eos bomea (n = 5), Eos reticulata (n = 4), Eos cyanogenia (n = 4). Detailed information concerning methodology, which is often missing in papers dealing with reference values, is included. As far as possible, data are compared with literature, and some thoughts on obvious deviations are given. The problem of establishing reference values in rare species is reviewed.

Animals↗

PubMed1999

Comparison of lung-function reference values.

OBJECTIVE: Lung-function reference values play an important role in medical surveillance examinations of occupational and environmental respiratory diseases, in stipulation of preventive measures, in initiation of therapeutic measures, and in granting of benefits to which individuals with lung injuries or occupational lung diseases are entitled (e.g., bronchial asthma, pneumoconiosis, or farmer's lung disease). Prediction equations most widely used are based on studies performed more than 20 years ago and may not represent the findings obtained in today's population. METHODS: We recorded case histories and lung function values of 139 healthy subjects (spirometric and plethysmographic data, T(LCO)) and computed the differences of measured values minus predicted ones as recommended by different authors. RESULTS: The means of these differences can be seen as shifts in our group versus the theoretical (predicted) values of various authors. These shifts, the standardized mean values of residuals, and their probability as determined under the assumptions of the respective regression model and the number of subjects below the threshold limits are given. FVC, FEV1, and FEV1%FVC show mostly good agreement with the recommendations by Crapo et al., Roca et al., Glindmeyer et al., Brändli et al., and Berger et al. Our IVC and FVC values do not differ significantly from each other. Normative flow-volume curve parameters of various authors deviate widely, however, and are not compatible with the values of our control group. Plethysmographically measured volumes (FRC, TLC, and RV) are only insufficiently reflected by Quanjer's reference equations. Measured T(LCO) and K(CO) show good agreement with the predictions of Cotes et al. [11] for females but display less concurrence with the predictions for males. CONCLUSIONS: Our results indicate that the ERS values of FVC, FEV1, and FEV1%FVC mainly applied in Europe should be verified. The much better-evaluated formulas of Brändli et al. are recommended. Furthermore, the age range between 60 and 70 years should be extrapolated from these formulas until better epidemiological data on lung function are available.

Adolescent↗

PubMedDate not supplied

Reference values for arm muscle area, arm fat area, subscapular skinfold thickness, and sum of skinfold thicknesses for American adults.

Reference values for the mid-upper arm muscle area, mid-upper arm fat area, subscapular skinfold thickness, and sum of triceps and subscapular skinfold thicknesses of American adults were developed from data collected by the National Center for Health Statistics during the first National Health and Nutrition Examination Survey, 1971 to 1974. The reference values were compared to other reference values derived from a similarly conducted cross-sectional survey of the American population, the Health Examination Survey of 1960 to 1962. These comparisons revealed that arm muscle area and subscapular skinfold thickness of men and arm muscle area of women continuously increase with aging from 18 to 74 yr; arm fat area and sum of skinfold thicknesses of men increase with aging from 18 to 34 yr but stabilize or decrease with further aging; and arm fat area, subscapular skinfold thickness, and sum of skinfold thicknesses of women increase with aging from 18 to 64 yr but decrease thereafter. As these parameters frequently change more than 20% over the period of a single decade, it is important that age be considered in nutritional evaluations based on anthropometric measurements. Changes in these four parameters with successive generations are also frequently large. Consequently, it is imperative that the reference values used in nutritional assessment protocols be updated at regular intervals.

Adipose Tissue↗

PubMed1998

Hematology and chemistry reference values for free-ranging harbor seals (Phoca vitulina) and the effects of hemolysis on chemistry values of captive harbor seals.

Most reported laboratory reference values for harbor seals (Phoca vitulina) are derived from captive seals, or stranded seals that have recovered from disease in marine mammal centers. This study established hematology and serum chemistry reference values for free-ranging harbor seals, using methods and that are current and readily available, and determined the effects of hemolysis on serum chemistry values of captive harbor seals. Blood samples were collected for hematologic and serum chemistry measurements from 14 clinically normal, adult male and female harbor seals and two juvenile harbor seals (approximate age 6 mo) captured in saltwater sloughs and estuaries near Moss Landing, California, USA. Values for amylase, globulin, and differential leukocyte count, not previously reported, were determined. In general, hematology and chemistry values in adults were similar to those reported for free-ranging and captive harbor seals, except for glucose, urea nitrogen, and lactate dehydrogenase (LDH) values, which were higher than those reported previously. Red blood cell counts in the two juveniles were higher than in adults and in young harbor seals studied previously. To determine the effects of hemolysis on serum chemistry values, two intensities of hemolysis were generated experimentally in blood collected from 11 harbor seals recovering from injuries or stranding at the Marine Mammal Center (Sausalito, California 94965, USA). Moderate hemolysis (++, 1 g/L hemoglobin, red-tinged) significantly increased LDH activity, whereas severe hemolysis ( , 2 g/L hemoglobin, cherry red) significantly increased total protein, albumin, calculated globulin, LDH, and total bilirubin and significantly decreased creatinine. The effects of hemolysis must be considered when chemistry results of harbor seals are interpreted.

Animals↗

PubMed2002

Reference values of body mass at. birth among native northern population of Russia.

Infants with body mass at birth deviating from the mean values exhibit higher level of mortality. The absence of the expressed phenotype deviations refers to the preservation and heredity of the most adopted genotypes (reference values). The newborns out of the adaptive norm are morbidity-prone. The reference value for body mass at birth was studied in the indegenous populations of the Kola Peninsula, Siberia, Far East and the Urals. By our data the Arctic Saami and the Far East Nanais show the reference values more distinct from other. Lasting (many-centuries-long) adaptation to specific environmental conditions leads to development of a special phenotype complex. The Saami and Nanais are the most representative populations of the arctic and the monsoon climate zones. Accordingly, the parameters of reference values of their newborns are significantly different from the characteristics of the infants of the moderate climate zone.

Anthropometry↗

PubMed2000

Population-based body mass index reference values from Göteborg, sweden: birth to 18 years of age.

UNLABELLED: The body mass index or BMI (weight/height2) is a somewhat crude estimate of nutritional status. However, due to its simplicity and high correlation with total body fat, it has been the method of choice in both paediatric clinics and research over the years. Since BMI is not an equivalent measure of the percentage of body fat in different ethnic groups and in the two sexes, population-specific BMI reference data is needed. Several BMI reference values have been published for French, American, British and Hong Kong children in recent years. In Sweden, weight-for-age and height-for-age reference values, which were published in 1976, are still used as the current national growth reference values. Updated growth reference values are needed for assessing nutritional status due to the secular trend toward and increasing prevalence of childhood obesity. The aim of this study was to produce BMI reference values for Swedish children of paediatric age. The series came from a large Swedish population-based longitudinal growth study of 3650 full-term babies followed from birth to 18 y of age. The children in this data set were born in the early 1970s. The pattern and level of 50th centile BMI values presented here are quite similar to those of the Swedish cohort study in the 1950s. In comparison with the US BMI reference values, the Swedish values are much lower, especially for the higher centile values. CONCLUSION: The new Swedish BMI chart from our study may provide a useful tool for paediatricians to assess body fat, and consequently nutritional status, in Swedish children.

Adolescent↗

PubMed1999

[Reference values of FSH, LH, total testosterone, free testosterone, 17-beta-estradiol and SHBG in healthy children in Zaragoza].

OBJECTIVE: Our purpose was to estimate reference values for basal serum concentrations of follicle-stimulating hormone (FSH), luteinizing hormone (LH), total testosterone, free testosterone, 17-beta-estradiol (E2) and sex steroid binding globulin (SHBG) in healthy children of Zaragoza. PATIENTS AND METHODS: The reference population consisted of healthy children between 0 and 14 years of age with normal weight and height and living in the metropolitan area of Zaragoza (Spain). It was a transversal study. Basal serum concentrations of FSH, LH and SHBG were measured by immunoradiometric assay. Basal serum concentrations of total testosterone, free testosterone and E2 were analyzed by radioimmunoassay. Reference values and ranges were estimated according to the recommendations of the International Federation of Clinical Chemistry. RESULTS: Reference values have been classified by age, sex and pubertal stage. Serum concentrations of FSH, LH, total testosterone, free testosterone and E2 increase during the first six months, remain low in infancy and rise during puberty. All of these concentrations showed marked differences according to sex. Serum SHBG levels are influenced by age and during puberty by sex. CONCLUSIONS: Differences in reference values for gonadotrophins, sex steroids and SHBG during infancy, childhood and adolescence makes it necessary for every population to establish their own reference values according to age, sex and pubertal stage.

Adolescent↗

PubMed1999

[Reference values for thyroid hormones, thyrotropin and thyroglobulin in healthy children of Zaragoza].

OBJECTIVE: The purpose of this study was to estimate the basal serum concentration reference values for total T3 (T3), total T4 (T4), free T4 (FT4), thyrotropin (TSH) and thyroglobulin (Tg) in healthy children of Zaragoza. PATIENTS AND METHODS: Healthy children aged 0 to 14, with normal weight and height, living in the metropolitan area of Zaragoza (Spain) were the reference population of this transversal study. Basal serum concentrations of T3, T4 and FT4 were measured by radioimmunoassay and of TSH and Tg by immunoradiometric assay. Reference values and ranges were estimated according to the recommendations of the International Federation of Clinical Chemistry. RESULTS: Reference values have been classified according to age, sex and pubertal stage. There are differences in T3, T4, FT4 TSH and Tg concentrations during the prepubertal period according to age, but not to sex, and between the prepubertal period and puberty. Sex and Tanner stage influence T3 and T4 concentrations during puberty. CONCLUSIONS: Since there are differences in T3, T4, FT4, TSH and Tg reference values according to age, sex, pubertal stage and immunoassays, it is necessary to establish reference values for every population and laboratory in accordance with these parameters.

Adolescent↗

PubMed1980

[Creatine kinase "NAC-activated": reference values for children (author's transl)].

Reference values for 327 children aged between 1 day and 15 years are given for the revised standard method for the determination of serum creatine kinase (CK) activity by activation with N-acetylcysteine (NAC). No sex-dependence could be observed, but CK activity was found to vary markedly with age. The following values are suggested as upper limits of the reference ranges for measurements at 25 degrees C: neonates: 1-3 days: less than or equal to 370 U/l, 4-10 days: less than or equal to 200 U/l, 11-31 days: less than or equal to 100 U/l; children (2 months-15 years): less than or equal to 90 U/l.

Acetylcysteine↗

PubMed1982

Standardization of blood specimen collection procedure for reference values. International Committee for Standardization in Haematology (ICSH).

This document has been prepared by an ICSH Task Force as a proposed ICSH Standard for Blood Specimen Collection for Reference Values. The procedures described are a model for standardization of blood specimen collection either for people confined to bed, or for those who are ambulant; they are intended for obtaining reference values using the principles described in the ICSH paper on the Theory of Reference Values (Clin. lab. Haemat. 3, 369-373, 1981). The document is based on recommendations by the Committee on Reference Values of the Scandinavian Society for Clinical Chemistry and Clinical Physiology as published in Scand. J. clin. lab. Invest. (35, Suppl. 144, 39-43, 1975); it has been prepared in collaboration with the Panel on the Theory of Reference Values of the Scientific Committee of the International Federation of Clinical Chemistry (IFCC). The responsible authorities of ICSH and IFCC have proposed that it should be the basis for joint recommendations by both organizations.

Blood Preservation↗

PubMedDate not supplied

Reference values of erythrocyte sedimentation rate of adult healthy subjects.

BACKGROUND: The purpose of this paper is to provide a scientific basic (rather than basic) for a unified standard of the erythrocyte sedimentation rate (ESR) reference value of healthy subjects in China between the ages of 41 and 75 years [corrected]. METHODS: ESR reference values of healthy subjects between 41 and 75 years of age were collected according to Wintrobe methods. The relationship between these healthy subjects' ESR reference values and altitude was tested in this paper. RESULTS: It was found that the ESR reference value of 41- to 75-year-old healthy subjects decreases when altitude gradually increases; the relationship is quite significant. Method of mathematical univariate regression analysis was used to deduce two regression equations: Y (1) = 14.89-0.00273 X +/- 3.52, and Y (2) = 23.92-0.00423 X +/- 5.34. CONCLUSION: If the altitude value of a particular area of China is known, ESR reference value of healthy subjects (41-75 years) ) can be calculated by regression equations. Furthermore, in terms of altitude, China can be divided into the following three districts: Qingzang District; Central District, and Eastern District.

Adult↗

PubMed1997

Reference values of urinary chromium in Italy.

OBJECTIVES: The paper describes the results of a polycentric study for the assessment of reference values of urinary chromium (U-Cr) in the Italian population. METHOD: A total of 890 subjects (58.3% males and 41.7% females) were selected on the basis of standardized criteria in eight different areas of Italy. Urinary chromium was determined on morning spot samples collected using standardized procedures. The U-Cr was determined independently by three laboratories using an Electrothermic atomization-Atomic Absorption Spectrometry (ETA-AAS) method with a detection limit of 0.05 microgram/l, adopting-for the statistical analysis-the median value of the results of the three laboratories. The between-laboratories within-subjects standard deviation was 0.049 microgram/l. Due to the high proportion (approx, 28%) of undetectable chromium levels, the geometric mean (GM) and geometric standard deviation (GSD) were estimated using a procedure of linear interpolation. The analysis of the effects of some variables (sex, age, center, residence, smoking and drinking habits) on the U-Cr values, was also performed, by multiple regression analysis after logarithmic transformation, using GM and SD. RESULTS: The reference value of U-Cr was of 0.08 microgram/l as an estimated GM, whereas the expected distribution ranged from not detectable (nd) (95% CI = nd-0.06) to 0.24 microgram/l (95th percentile; 95% CI = 0.20-0.31). Among the variables studied, only geographical area and sex significantly influenced the U-Cr levels. In subjects selected in the provinces of Bari and Venice values of U-Cr were significantly lower than those determined in subjects residing in other areas. CONCLUSIONS: From our investigation the reference values for U-Cr were lower than those obtained in previous investigations. In addition it confirms a further reduction in U-Cr levels following the previous decline reported in the 1970s and 1980s. In over 20 years U-Cr values in the general population dropped from values greater than 1 microgram/l to values between 0.5 and 0.2 microgram/l. The reasons of this progressive decline cannot be attributed in our opinion to a reduced intake of the metal, but mainly to the improvement in analytical instrumentation and methods. A further decrease may be ascribed to a more accurate definition of the reference groups and to a better control of pre-analytical factors. Considering that the reference values for U-Cr are much lower than those determined some decades ago, toxicological studies in order to verify the significance of biological limit values currently suggested for chromium seem to be necessary.

Adult↗

PubMed1990

[Principles of determining reference values in hematology].

A short explanation of fundamental terminology concerning reference values is presented. Criteria for formation of a reference group are discussed and the significance of standardization of blood collection and laboratory procedures is emphasized. Interpretation of reference values is founded on the probability theory and attention is directed to non-parametric statistics.

Hematologic Tests↗

PubMed1999

Determination of reference values for total PSA, F/T and PSAD according to prostatic volume in japanese prostate cancer patients with slightly elevated serum PSA levels.

BACKGROUND: For screening prostate cancer (CAP) using prostate-specific antigen (PSA), the indications of biopsies for patients showing slightly elevated PSA values are still controversial. Furthermore, the dependence of total PSA, free-to-total PSA ratio (F/T) and PSA density (PSAD) on prostatic volume in gray zone cases is unclear. METHODS: By analyzing 1913 patients with a serum total PSA ranging from 2.0 to 20 ng/ml, we evaluated the correlation between total PSA and age or prostatic volume and positive predictive value (PPV) in each range for total PSA, age and prostatic volume. Then suitable reference values for total PSA, F/T and PSAD were decided according to prostatic volume. RESULTS: There was no close correlation between PSA and age or volume. The PPV was high in the group with a prostatic volume of 10-30 ml. Prostatic volume was categorized into three groups, <20, 20-40 and > or =40 ml, and reference values for obtaining a sensitivity of 90% were proposed. The reference values of total PSA and PSAD were lowered and that of F/T was raised with increase in prostatic volume. The specificity was very low for the > or =40 ml group. The highest specificity of 36% in PSAD was obtained for the <20 ml group. CONCLUSION: The reference values for total PSA, F/T and PSAD must be changed according to prostatic volume in order to maintain a sufficient diagnostic sensitivity of CAP. Of these parameters, PSAD showed a high specificity in the group with a prostatic volume of <40 ml.

Adenocarcinoma↗

PubMed1997

[Dimensions of the proximal thoracic aorta from childhood to adult age: reference values for two-dimensional echocardiography. Ligurian Group of SIEC (Italian Society of Echocardiography)].

BACKGROUND: Two-dimensional echocardiography (2-DE) represents the main tool for detecting and monitoring abnormalities of proximal thoracic aorta. However, previous studies performed to assess the reference values of aortic diameters using this technique are few and, often, involve a small number of subjects. Furthermore, such a study has not been performed on an Italian population. METHODS: To assess the reference values and the growth curves of the dimensions of the proximal thoracic aorta in an Italian population, we measured aortic diameters at the level of the anulus, of the sinuses of Valsalva and of the supraaortic ridge, by using 2-DE, in 134 healthy volunteers (78 males, 56 females), aged 35 +/- 16 years (range 5-76). Sex, age, weight, height, body surface area (BSA), heart rate, systolic and diastolic blood pressure were analyzed as determinants of proximal thoracic aorta diameters. In addition, to compare the specificity of the reference values, we have obtained with those provided by literature, we studied another independent group of 23 healthy volunteers, aged 32 +/- 15 years (range 11-65). RESULTS: In our study population, mean values and range of aortic 2-DE diameters were 2.1 +/- 0.3 cm (range 1.3-2.9) at the level of the anulus, 2.6 +/- 0.4 cm (range 1.7-3.7) at the level of the sinuses of Valsalva and 2.4 +/- 0.4 cm (range 1.5-3.4) at the level of the supraaortic ridge. At multivariate regression analysis, sex and age emerged as the only independent determinants of the aortic root diameters (r2 = 0.35, 0.43, and 0.52 for aortic diameter at the level of anulus, sinuses of Valsalva, and supraaortic ridge, respectively). On average, aortic root dimensions at the level of the anulus, of the sinuses of Valsalva and of the supraaortic ridge in females were 1.5 mm, 2.8 mm, and 1 mm, respectively, smaller than those of males of comparable age, height and weight. The growth curves showed that proximal thoracic aorta increases in size in the first 30 years of life; thereafter, it remains relatively constant in size up to 55 years, after which the proximal thoracic aorta tends to enlarge gradually. The ratios of sinuses of Valsalva to annular diameter and of supraaortic ridge to annular diameter (1.27 +/- 0.17 and 1.17 +/- 0.16, respectively) were found to be indexes of aortic root dimension independent of sex and age. No correlation was found between aortic root dimensions and systolic blood pressure. M-mode echocardiography systematically overestimated 2-DE aortic diameters at the level of the anulus, as well as at the level of the sinuses of Valsalva and of the supraaortic ridge (+0.8 +/- 0.04 cm, +0.2 +/- 0.04 cm, and +0.4 +/- 0.04 cm, respectively, p < 0.0001 for all). In the control population, our reference values demonstrated a specificity significantly higher than that of the main reference values reported in literature (97 +/- 2% versus 62 +/- 4%, p < 0.0001). CONCLUSIONS: Our study provides a prospectic, systematic and detailed analysis of 2-DE proximal thoracic aorta diameters in a wide group of healthy Italian subjects. Our data show that: 1) 2-DE aortic root dimensions are influenced by sex and age but not by body size or blood pressure; 2) the ratios of sinuses of Valsalva to annular diameter and of supraaortic ridge to annular diameter are indexes of aortic root dimension which are independent of age and sex; 3) M-mode diameter systematically overestimates 2-DE diameters of the aortic root; and 4) Italian population based reference values showed higher specificity than values provided by literature.

Adolescent↗

PubMed1997

[Reference values for lead levels in blood for the urban population].

INTRODUCTION: The lead reference values for blood used in Brazil come from studies conducted in other countries, where socioeconomic, clinical, nutritional and occupational conditions are significantly different. In order to guarantee an accurate biomonitoring of the population which is occupationally exposed to lead, a major health concern of the studied community, reference values for individuals who are not occupationally exposed and who live in the southern region of the city were established. MATERIAL AND METHOD: The sample was composed of 206 subjects of at least 15 years of age. Various strategies were employed to assure good-quality sampling. Subjects who presented values outside clinical or laboratory norms were excluded, as well as those whose specific activities might interfere with the results. RESULTS: Lead reference values for blood were found to be from 2.40 to 16.6 micrograms.dL-1, obtained by the interval x +/- 2s (where x is the mean and s is the standard deviation form observed values) and the median was 7.9 micrograms.dL-1.

Adolescent↗