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PubMed1997

[Selection criteria for the establishment of reference values in tropical zones. Application to specific proteins: C-reactive protein, haptoglobin, transferrin in gabonese children].

About 220 children (110 boys and 110 girls) aged 18 months to 10 years, 65.9% have been selected from anamnesis, clinical, and biological criteria to produce reference values on specific proteins dependent inflammatory, anemia and hemolysis (C-reactive protein = CRP; Transferrin = TRF and Haptoglobin: HPT). Specimens have been analysed by Nephelometric immuno-chemical method. For the two groups, A1 [18 months-5 years] and A2 [5-10 years], the reference values of the whole study population are reported: CRP (A1 3.35 +/- 3 mg/l: A2 2.40 +/- 2.30 g/l, with a significant difference at Student Fisher "t" test p < 0.03); TRF (A1 4.05 +/- 1.5 g/l; A2 4.50 +/- 1.4 g/l; NS, p > 0.05) HPT (A1 2.55 +/- 2.0 g/l: A2 1.20 +/- 1.10 g/l; S(r) p < 10(-5)). Furthermore, for TRF, HPT we must consider the sex in the results meaning because of significant difference into boys and girls.

Age Factors↗

PubMed2001

Year-long validation study and reference values for urinary amino acids using a reversed-phase HPLC method.

BACKGROUND: Reversed-phase HPLC (RP-HPLC) has become an alternative to ion-exchange chromatography for amino acid analysis in biological fluids. However, validation studies for its urine application are limited, and the corresponding reference values have not been reported extensively. We studied the long-term performance of a commercial HPLC method for urine amino acid analysis and established specific age-related reference values for urine amino acid excretion. METHODS: Method performance was continuously assessed by recovery and precision studies with urine samples and controls, respectively. Healthy individuals were prospectively analyzed throughout a 5-year period. Excretion of individual amino acids, expressed as mmol/mol of creatinine, was included in six age-related groups for random urine samples (0-1 month, 1-12 months, 1-3 years, 3-8 years, 8-16 years, and >16 years) and in two groups for 24-h urine collections (8-16 years and >16 years). RESULTS: Over a 1-year period, CVs for retention times were <0.5% and 3.3% for within- and between-run imprecision, respectively. For amino acid concentrations, within-run CVs were 2.9-17% and between-run CVs were 7.1-46% for the same period. Amino acid recoveries were 78-122%. Reference intervals for 35 amino acids were calculated and compared with the concentrations observed in patients diagnosed with specific pathologies. A few statistically significant differences were found between the reference intervals derived using random and 24-h urine collections. CONCLUSIONS: Long-term reliability of the RP-HPLC method for urine amino acid analysis has been demonstrated. Representative age-related reference intervals for the RP-HPLC method in both random urine and 24-h urine collections have been established, and their feasibility for diagnosis of aminoaciduria has been shown. These intervals could serve as a guide for laboratories changing to HPLC methods.

Adolescent↗

PubMed2000

Reference values of fat-free and fat masses by bioelectrical impedance analysis in 3393 healthy subjects.

Determination of fat-free mass (FFM) and fat mass (FM) is of considerable interest in the evaluation of nutritional status. In recent years, bioelectrical impedance analysis (BIA) has emerged as a simple, reproducible method used for the evaluation of FFM and FM, but the lack of reference values reduces its utility to evaluate nutritional status. The aim of this study was to determine reference values for FFM, FM, and %FM by BIA in a white population of healthy subjects, to observe the changes in these values with age, and to develop percentile distributions for these parameters. Whole-body resistance of 1838 healthy white men and 1555 women, aged 15-64 y, was determined by using four skin electrodes on the right hand and foot. FFM and FM were calculated according to formulas validated for the subject groups and analyzed for age decades. This is the first study to present BIA-determined age- and sex-specific percentiles for FFM, FM, and %FM for healthy subjects, aged 15-64 y. Mean FM and %FM increased progressively in men and after age 45 y in women. The results suggest that any weight gain noted with age is due to a gain in FM. In conclusion, the data presented as percentiles can serve as reference to evaluate the normality of body composition of healthy and ill subject groups at a given age.

Adipose Tissue↗

PubMed1989

Normal reference values for regional pulmonary peripheral airspace epithelial permeability. Influence of pneumonectomy and the smoking habit.

Peripheral airspace epithelial permeability (PAEP) to diethylentriaminopentacetate (DTPA), an index of pulmonary integrity, was measured in 3 groups of subjects for different purposes: (1) to establish vertical regional reference values; (2) to determine the physiological role of acute doubling of total pulmonary blood flow; (3) to quantify the pulmonary epithelial damage in smokers and the possibility of lung protection by an agent stimulating surfactant production. This study broadens previous knowledge of PAEP. First of all, regional reference values are given for young normal nonsmoking subjects and the existence of a vertical gradient of PAEP is confirmed. Furthermore, this study shows that this gradient is independent of the vertical blood flow gradient, since an acute increase of total blood flow in pneumonectomized patients does not modify the regional distribution of PAEP. Finally, it is confirmed that the cigarette smoker's lung is more permeable than the controls and that probably a drug-stimulating surfactant production gives some protection against damage due to chronic smoking.

Adult↗

PubMed2006

Reference values for performance on the Automated Neuropsychological Assessment Metrics V3.0 in an active duty military sample.

The Automated Neuropsychological Assessment Metrics (ANAM) is a computerized measure of processing speed, cognitive efficiency, and memory. This study describes performance and psychometric properties of ANAM in an active duty, healthy military sample (N = 2,371) composed primarily of young (18-46 years) adult males. Rarely have neuropsychological reference values for use with individuals in the military been derived from a large, active duty military population, and this is the first computerized neuropsychological test battery with military-specific reference values. Although these results do not provide demographically corrected, formal normative data, they provide reference points for neuropsychologists and other health care providers who are using ANAM data in research or clinical settings, with patients of comparable demographics to the present sample.

Adolescent↗

PubMed2000

Trace element reference values in serum determined by inductively coupled plasma atomic emission spectrometry.

Serum reference values for Ba, B, Cd, Cu, Fe, Mn, Li, Se, Sr, and Zn in 141 healthy Norwegians were determined. The trace element concentrations were determined by the inductively coupled plasma atomic emission spectrometry technique that we have recently validated. The reference intervals were established according to the recommendations of the International Federation of Clinical Chemistry and Laboratory Medicine. Also coverage intervals with coverage uncertainties were calculated according to the International Union of Pure and Applied Chemistry. The population studied consisted of 69 men and 72 women of the ages 21-87 years. The effects of gender, age, smoking, and oral contraceptives on serum levels of trace elements were investigated. Median concentrations of the different trace elements in (micromol/l) were as follows: Ba (0.44), B (1.50), Cd (0.004), Cu (17.1), Fe (21.4), Li (0.06), Mn (0.003), Se (1.26), Sr (0.17), and Zn (13.3). An increase in serum Ba and Sr was detected with age. These metals and Se were also significantly higher in women over 50 years of age in comparison to younger women. Women had higher serum Cu than men and those on oral contraceptives had higher serum Cu and Fe. Serum B tended to increase with age, while it was significantly reduced with smoking.

Adult↗

PubMed1981

[Interest of the determination of reference values for the monosaccharide composition of the human erythrocyte membrane (author's transl)].

The carbohydrate composition of the human erythrocyte membrane was just established ten years ago. Carbohydrates have crucial functions in the membrane structures and the determination of this composition may have an important semeiological signification. In this way, reference values are necessary. The existence of possible variations of the composition with two physiological parameters: the groups in the ABO system and the age of erythrocytes have been investigated and are reported. Their repercussion on the determination of reference values is discussed.

Blood Group Antigens↗

PubMed1997

Studies on some trace and minor elements in blood. A survey of the Kalpakkam (India) population. Part II: Reference values for plasma and red cell, and correlation with coronary risk index.

Since data on the trace element levels in Indian population are lacking, we chose to conduct a survey of the Kalpakkam township population. People in the age group 40-55 were included in this study. Reference values for trace and minor elements of the blood of the Kalpakkam population were arrived at by carrying out the analysis of plasma and red cells of healthy subjects of the Kalpakkam population. Although the "reference values" for many elements were found to be normal and comparable to values available in the literature, slight deficiency with respect to Se was noticed. Subjects with high coronary risk index were also included in the study to assess the possible correlation of elemental and lipid profile. A study of box plots showed that the elements Se, Mg, Na, K, and Fe show significant differences between "high risk" coronary risk index (CRI > 5) and "no risk" (CRI < 4.5). In the plasma, the levels of Mg, Na, and K were found to be less in the high-risk group. In red cells, the amount of Se, Fe, and K were found to be significantly less in the "high-risk" group as compared to the "no-risk" group.

Adult↗

PubMed2001

Reference values for alveolar membrane diffusion capacity and pulmonary capillary blood volume.

The reference values for diffusion capacity of the alveolar capillary membrane (Tm,CO) and pulmonary capillary volume (Qc) are scarce, while the standard deviations of the equations are large. New equations and residual standard deviations (RSDs) were determined in a sample of healthy subjects. Tm,CO and Qc values were measured in 117 (72 females, 45 males) nonsmoking healthy subjects. The carbon monoxide transfer factor (TL,CO) was determined when the volunteer was breathing room air and subsequently, when the volunteer was breathing 100% oxygen. From these data, Tm,CO and Qc values were calculated. The females' TL,CO was 3.15 mmol x min(-1) x kPa(-1) lower than the males', apparently caused by lower female lung volume. Tm,CO and Qc were lower in females, but correction for lung volume eliminated this difference. Qc(-1) reference equations for females and males, respectively, are 4.375 x 10(-2) - 1.085 x l0(-2) x height and 4.455 x 10(-2) -1.085 x 10(-2) x height (RSD for both sexes: 2.544 x 10(-3)). Tm,CO(-1) reference equations for females and males, respectively, are 0.111+3.304 x 10(-4) x age-4.753 x 10(-2) x height and 0.127+3.304 x 10(-4) x age-4.753 x 10(-2) x height (RSD for both sexes: 1.085 x 10(-2)). The general character of these equations complies with earlier publications, the only difference being that the RSDs are 1.18-2.76 times lower. New reference equations for diffusion capacity of the alveolar capillary membrane and pulmonary capillary volume are available with considerably smaller residual standard deviations.

Adult↗

PubMedDate not supplied

Reference values for a multiple repetition 6-minute walk test in healthy adults older than 20 years.

PURPOSE: To (1) identify greatest 6-minute walk distance (6MWD) from among several repetitions (best 6MWD) in a wide age range of healthy volunteers to develop reference values for the multiple repetition 6MWD, and (2) investigate the influence of demographics, anthropometrics, and habitual exercise activity on best 6MWD. METHODS: Four 6MWD were performed on the same day in a 20-meter corridor by 41 male and 38 female healthy volunteers ranging in age from 20 to 80 years. The greatest 6MWD by each subject from among four 6MWDs was the primary outcome measure. RESULTS: Eighty-six percent had their best 6MWD after the first walk; an average increase of 43 meters was observed from first to best 6MWD (P < 0.003). Best 6MWD averaged 698 +/- 96 meters and was inversely related to age (P < 0.001), directly to height (P < 0.001), and was greater in men than women (P < 0.0002). A regression model accounted for 41% of between-subject variability in best 6MWD (P < 0.00000001). In a subset of older subjects, predicted 6MWD significantly underestimated measured best 6MWD when reference values were used from another study where test familiarization was not provided, but this difference disappeared when value were used from the present and a third study where test familiarization was provided. CONCLUSIONS: The present study is the first to provide predicted 6MWD values performed with multiple repetitions and for subjects in the 20-40-year-old age range. Selection of appropriate predicted 6MWD values for interpretation of performance should be guided by subject age and degree of test familiarization provided.

Adult↗

PubMed1997

[Reference values, metabolism and findings of abnormal values of magnesium in childhood].

In the introduction we summarize specifics of reference values and metabolism of magnesium in childhood. We studied the frequency of abnormal values of magnesium in both children and adults hospitalized in Faculty Hospital Motol, Prague. We analyzed 6761 tests of S-Mg and 356 dU-Mg results located in archives of Department of clinical biochemistry (1. 1. 1992-1. 11. 1995). The frequency of low level of S-Mg (< 0.65 mmol/l) was 14%. Hypermagnesemia was present in 1.6% of the total number of cases. We found low values of dU-Mg in 20% of the total number of cases, hypermagnesiuria was present in 8.4% cases. We also proved that hypomagnesemia is more frequent in both boys and men than in girls and women. Critical values of S-Mg below 0.5 mmol/l are less frequent (84 cases). Estimated frequency of clinical significant hypomagnesemia in hospitalized patients was about 1.25%.

Adolescent↗

PubMed1981

[Pancreatic lipase: reference values at 25 degrees C (author's transl)].

Development of a new specific test for estimation of pancreatic lipase activity (EC 3.1.1.3.) required establishment of reference values. An upper reference range of 170 to 190 U/l at 25 degrees C was determined from a group of 368 females and 435 males aged 20 to 70 years. Values below 170 U/l are very likely to be normal, values above 190 U/l are considered pathological. Values between 170 and 190 U/l require further controls. For practical reasons age and sex dependency need not be accounted for as these influences are negligible.

Age Factors↗

PubMed2005

Establishing reference values for both total soluble Fms-like tyrosine kinase 1 and free placental growth factor in pregnant women.

It has been reported that the concentration of free placental growth factor (PIGF) is decreased and that of soluble fms-like tyrosine kinase 1 (sFlt-1) is increased before the onset of preeclampsia. However, no study has determined the reference values for sFlt-1 and free PIGF during pregnancy using a commercially available enzyme-linked immunosorbent assay (ELISA) kit. This longitudinal cohort study was undertaken to address this issue. Serum samples were collected from 148 women at 10, 18, 28, and 37 weeks of gestation. Preeclampsia occurred in 6 women: 4 women who delivered at <37 weeks of gestation, and 2 women who delivered at > or =37 weeks. The average and 90% confidence interval (90% CI) of the serum concentration of both sFIt-1 and free PIGF were determined in a total of 433 specimens from 148 subjects with 1 to 4 collections at 7 to 39 weeks of gestation, and were represented as quadric curves. The mean values (90% CI) of sFlt-1 (pg/ml) at 10, 18, 28, and 37 weeks of gestation were 413 (174-981), 296 (125-704), 413 (174-982), and 1,130 (477-2,690), respectively. The mean values (90% CI) of free PIGF (pg/ml) were 36 (14-89), 206 (83-515), 518 (207-1,290), and 354 (142-884), respectively. We also established the reference values for the ratio of sFlt-1/PIGF. These values may be useful for predicting the subsequent occurrence of preeclampsia.

Adult↗

PubMed1998

Neuron-specific enolase: reference values in cord blood.

With foetal sonography prenatal detection of tumours has become more frequent. To evaluate and treat these infants it is necessary to identify the tumour postnatally. Elevated neuron-specific enolase is a biochemical marker of neuroblastoma. Since conditions during birth may influence neuron-specific enolase concentration in foetal serum, specific reference values in cord blood are required. Cord blood samples were taken from 192 healthy term newborns and concentration of neuron-specific enolase was measured by enzyme immunoassay (EIA). Median neuron-specific enolase concentration in the reference group was 8.0 micrograms/l and the 5th-95th percentiles were 4.8-19.4 micrograms/l. No differences between male and female newborns were detected (p = 0.13). Measurement of neuron-specific enolase in cord blood, in comparison with our reference values, offers an early postnatal possibility of confirming the diagnosis of neuroblastoma.

Biomarkers, Tumor↗

PubMed2005

Reference values for ethylenethiourea in urine in Northern Italy: results of a pilot study.

This study was carried out to define reference values for urinary ethylenethiourea (ETU) in the Northern Italy population and to identify the sources of exposure. Ninety-five healthy subjects were selected. A spot urine sample was collected in the morning, and analyzed using GC/MS in the EI/SIM mode. Thirty-nine subjects showed urinary ETU concentrations lower than the limit of detection (LOD, 0.4 microg/g creatinine), and the remainders ETU concentrations ranging from 0.5 to 11.6 microg/g creatinine. No correlation was shown between smoke or alcohol intake and urinary ETU concentrations. Based on data on ethylene-bis-dithiocarbamate (EBDC) concentrations in food, we estimated a total EBDCs intake of 31.7-50.1 microg/day. These values are largely below the ADIs, but explain the presence of small amounts of ETU in the urine samples we have analyzed. Finally, it was estimated that the mean ETU in urine in the Italian general population is 0.6-0.8 microg/g creatinine, with a 95th percentile of 4.5-5.0 microg/g creatinine. These values can be used as reference, to compare the results of biological monitoring activities carried out on EBDCs occupationally and environmentally exposed populations.

Adult↗

PubMed1997

Immunophenotyping of blood lymphocytes in childhood. Reference values for lymphocyte subpopulations.

OBJECTIVE: Immunophenotyping of blood lymphocytes is an important tool in the diagnosis of hematologic and immunologic disorders. Because of maturation and expansion of the immune system in the first years of life, the relative and the absolute size of lymphocyte subpopulations vary during childhood. Therefore we wished to obtain reference values for the relative and the absolute size of all relevant blood lymphocyte subpopulations in childhood. STUDY DESIGN: We used the lysed whole blood method for analysis of lymphocyte subpopulations in 429 blood samples from neonates (n = 20), healthy children (n = 358), and adults (n = 51). The following age groups were used: 1 week to 2 months (n = 13), 2 to 5 months (n = 46), 5 to 9 months (n = 105), 9 to 15 months (n = 70), 15 to 24 months (n = 33), 2 to 5 years (n = 33), 5 to 10 years (n = 35), and 10 to 16 years (n = 23). RESULTS: Our results show that the absolute number of CD19+ B lymphocytes increases twofold immediately after birth, remains stable until 2 years of age, and subsequently gradually decreases 6.5-fold from 2 years to adult age. The CD3+ T lymphocytes increase 1.5-fold immediately after birth and decrease threefold from 2 years to adult age. The absolute size of the CD3+/CD4+ T-lymphocyte subpopulation follows the same pattern as the total CD3+ population, but the CD3+/CD8+ T lymphocytes remain stable from birth up to 2 years of age, followed by a gradual threefold decrease toward adult levels. In contrast to B and T lymphocytes, the absolute number of natural killer cells decreases almost threefold in the first 2 months of life and remains stable thereafter. Our study also showed that changes in the absolute size of lymphocyte subpopulations are not always consistent with changes in their relative size. This demonstrates that the relative counts of lymphocyte subsets do not reflect their actual size and are therefore of limited value. CONCLUSION: On the basis of this study we strongly recommend that immunophenotyping of blood lymphocytes for the diagnosis of hematologic and immunologic disorders be based on the absolute rather than on the relative size of lymphocyte subpopulations. Our data can be used as age-matched reference values for blood lymphocyte immunophenotyping.

Adolescent↗

PubMed1997

Biochemistry reference values for Quebec lactating dairy cows, nursing sows, growing pigs and calves.

Reference values for lactating dairy cows, nursing sows, growing calves and pigs were established on jugular cannulated animals. On each day of sampling, 13 samples were taken every hour from dairy cattle, growing calves and pigs and 5 samples were taken every 2 h from nursing sows to minimize day and analysis bias. Results show that aging influences more biochemical factors in pigs than in calves, and in nursing sows variations observed between day 5 and 15 after farrowing are of greater amplitude than between day 15 and 25.

Aging↗

PubMed2005

Determination of a reference value for N(G), N(G)-dimethyl-L-arginine in 500 subjects.

BACKGROUND: Asymmetric dimethylarginine (ADMA) acts as an endogenous inhibitor of NO-synthase. In the last years ADMA has emerged as a cardiovascular risk factor. The aim of this study was to determine a reference value for ADMA. METHODS: Plasma samples of 500 healthy subjects in the 19-75 year age group were analyzed. Exclusion criteria from this study were smoking, any known significant disease, body-mass-index (BMI) above 30 kg m(-2), elevated plasma lipid levels, impaired renal function, hypertension, and intake of any medication. The ADMA levels were determined by ELISA, (DLD Diagnostics, Hamburg, Germany). RESULTS: Mean ADMA plasma concentration of the total population was 0.69 micromol L(-1) (SD 0.20) and 95% of the measured values were in the range from 0.36 micromol L(-1) to 1.17 micromol L(-1). Women below 50 years of age had lower ADMA levels than men below 50 years of age [0.62 (0.17) micromol L(-1) vs. 0.69 (0.19) micromol L(-1); P = 0.001] and woman above 50 years of age had higher ADMA levels than men above 50 years of age [0.80 (0.22) micromol L(-1) vs. 0.73 (0.20) micromol L(-1); P = 0.036]. A regression analysis of ADMA levels and age was performed for each sex. The regression factor was r = 0.444 for women in a squared regression model (P < 0.001) and r = 0.212 for men in a linear regression model (P < 0.001). CONCLUSION: The study was able to define a reference value for ADMA plasma levels with 0.36-1.17 micromol L(-1) and found sex dependent correlations between ADMA and age. Women showed a significant increase in ADMA plasma levels with onset of menopause.

Adult↗