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PubMed1993

The role of genetics in defining reference values and health status.

Since its establishment, the Center for Preventive Medicine in Vandoeuvre-les-Nancy, France, performed specific studies on healthy humans, and its approach was very useful for defining reference values. Prevention should extend its interest to chronic diseases. The majority of important adult disorders are partially genetically determined. Genetic markers are also useful as exclusion or as partition criteria in the production of reference values. Results are presented that were obtained for apolipoproteins E, B and AIV, frequencies of these polymorphisms in the Lorraine population, and relationships between these polymorphisms and lipid metabolism-related parameters. Health checkup centers, in particular those involved in family screening, are well suited for resembling many data concerning environmental factors: tobacco consumption, alimentation habits, or alcohol and drug consumption. Simultaneous determination of genetic markers could allow the determination of an individual's susceptibility or resistance to developing a disease and to prepare a preventive action.

Environmental Exposure↗

PubMed2006

Clinical chemistry reference values for 75-year-old apparently healthy persons.

BACKGROUND: Clinical chemistry reference values for elderly persons are sparse and mostly intermixed with those for younger subjects. To understand the links between metabolism and aging, it is paramount to differentiate between "normal" physiological processes in apparently healthy elderly subjects and metabolic changes due to long-lasting diseases. The Vienna Transdanube Aging (VITA) study, which began in 2000 and is continuing, will allow us to do just that, because more than 600 male and female volunteers aged exactly 75 years (to exclude any influence of the "aging" factor in this cohort) are participating in this study. METHODS: Extensive clinical, neurological, biochemical, psychological, genetic, and radiological analyses, with a special emphasis on consumption of medication and abuse of drugs, were performed on each of the probands. The multitude of data and questionnaires obtained made possible an a posteriori approach to select individuals fulfilling criteria for a reference sample group of apparently healthy 75-year-old subjects for our study. Specific analytes were quantified on automated clinical analyzers, while manual methods were used for hormonal analytes. All clinical chemistry analytes were evaluated using in-depth statistical analyses with SPSS for Windows. RESULTS: In all, reference intervals for 45 analytes could be established. These include routine parameters for the assessment of organ functions, as well as hormone concentrations and hematological appraisals. Because all patients were reevaluated after exactly 30 months in the course of this study, we had the opportunity to reassess their health status at the age of 77.5 years. This was very useful for validation of the first round data set. Data of the second round evaluation corroborate the reference limits of the baseline analysis and further confirm our inclusion and exclusion criteria. CONCLUSIONS: In summary, we have established a reliable set of reference data for hormonal, hematological, and clinical chemistry analytes for elderly subjects. These values will be very useful for our future attempts to correlate disease states and aging processes with metabolic factors.

Aged↗

PubMed1990

Diet-related reference values for plasma amino acids in newborns measured by reversed-phase HPLC.

We have measured by reversed-phase HPLC concentrations of amino acids in plasma in groups of 80 normal appropriate-weight term babies fed from birth either a casein formula (WhiteCap SMA, n = 26), a whey formula (Gold Cap SMA, n = 26), or breast milk (n = 28). They were studied from day 11 to week 15 postpartum. The trend was towards an increase in amino acid concentrations in plasma with age, more marked in formula-fed than in breast-fed infants. Reference values were derived for each group. Both formula-fed groups showed several differences from the breast-fed group. Detailed examination indicated that tyrosine, phenylalanine, and methionine concentrations were increased in the casein-fed group greater than 20% of the time, but only threonine was similarly increased in the whey-fed group. Other amino acids, different ones for each formula group, were increased less frequently. There were no consistent correlations with any aspect of infant growth. Appropriate reference values are important for interpreting amino acid concentrations in plasma from newborns and for evaluating the effects of any future dietary modifications to infant formulas. HPLC analysis provides a suitable highly sensitive method for undertaking such studies.

Amino Acids↗

PubMed1997

Reference values for maximum work capacity in relation to body composition in healthy Dutch children.

Exercise performance is associated with physical development. For sick children, there is a need for parameters reflecting exercise performance, which should be easy to measure and should take their nutritional state into account. The aim of this study was to investigate the relationship between maximum work-load (Wmax) and body weight (BW) as well as fat-free mass (FFM) in healthy children performing an incremental maximum exercise test on a bicycle ergometer, and to develop reference values for Wmax corrected for nutritional state. A random sample of 158 children (77 boys and 81 girls), aged 12-18 yrs, underwent an incremental maximum exercise test on a bicycle ergometer. BW and FFM were also measured. Correlation analysis showed a significant association (p < 0.001) between BW and Wmax (boys: r = 0.82; girls: r = 0.73), and between FFM and Wmax (boys: r = 0.89; girls: r = 0.79). Two-way analysis of variance showed a significant effect of gender on variance of Wmax/BW ratio as well as Wmax/FFM ratio. The influence of age was significant for Wmax/FFM (p = 0.003), but not for Wmax/BW. The maximum workload/body weight ratio and the maximum workload/fat-free mass ratio are useful parameters of work capacity in bicycle exercise testing in children. The reference values (mean, SD, median, and percentiles) for boys and girls aged 12-18 years can be used to predict workload corrected for body composition in healthy and sick children.

Adipose Tissue↗

PubMed1999

Fetal ultrasound biometry: 1. Head reference values.

OBJECTIVE: To create reliable reference ranges and calculate Z scores for fetal head ultrasound biometry using a large sample size which is evenly distributed from 12 to 42 weeks of pregnancy. DESIGN: A prospective, cross-sectional study. SETTING: Obstetric clinics (outpatient and delivery units) at the University Hospital of Zurich. SAMPLE: The study data were obtained from 6557 pregnant women. METHODS: Only the first ultrasound examination between 12 and 42 weeks of each fetus with exactly established gestational age was used for analysis. No exclusions were made on the grounds of small-for-date birthweight, prematurity or other events several weeks after the examination. Separate regression models were fitted to estimate the mean and standard deviation at each gestational age for each parameter. RESULTS: A total of 6217 fetal head biparietal diameters and 5510 occipito-frontal diameters were measured. Both head circumference and cephalic index were derived in 5462 cases where both biparietal diameter and occipito-frontal diameter could be measured on the same fetus. The centile charts, tables and regression formulae for biparietal and occipito-frontal diameters, head circumference and cephalic index are presented. An application to calculate Z scores was developed using Excel (Microsoft Corporation, USA) and macros are presented in detail in the Figure 8 footnote. The comparison of our charts with those of the two most recent studies revealed almost no differences in biparietal diameter centiles. In one publication, occipito-frontal diameter charts, and in another, head circumference charts were different from the current study. CONCLUSIONS: We have presented centile charts, tables and regression formulae for fetal head ultrasound biometry derived from a large and minimally selected sample size in a carefully designed cross-sectional study. Complete tables and regression formulae to calculate reference ranges and Z scores are presented for use in computer-aided evaluation of fetal ultrasound biometry.

Adult↗

PubMed1999

Fetal ultrasound biometry: 2. Abdomen and femur length reference values.

OBJECTIVE: To create reliable reference ranges and calculate Z scores for fetal abdomen and femur ultrasound biometry using a large sample size which is evenly distributed from 12 to 42 weeks of pregnancy. DESIGN: A prospective, cross-sectional study. SETTING: Obstetric clinics (outpatient and delivery units) at the University Hospital of Zurich. SAMPLE: The study data were obtained from 6557 pregnant women. METHODS: Only the first ultrasound examination between 12 and 42 weeks of each fetus with certainly established gestational age was used for analysis. No exclusions were made on the grounds of small-for-date birthweight, prematurity or other events several weeks after the examination. Separate regression models were fitted to estimate the mean and standard deviation at each gestational age for each parameter. RESULTS: A total of 5807 mean abdominal diameters and abdominal circumferences were derived from fetal transverse and anterio-posterior fetal abdominal diameter measurements. Fetal femur length was measured in 5860 instances. The charts, tables and regression formulae of the biometrical measurements are presented. A comparison of our charts with others showed no significant difference. Only Merz's centiles for abdominal biometry were lower and for femur length higher than ours. An application to calculate Z scores was developed using Excel (Microsoft Corporation, USA); the macros are presented in detail in the Figure 6 footnote. CONCLUSIONS: We have presented centile charts, tables and formulae for fetal abdominal diameter and circumference and femur length derived from a large and minimally selected sample size in a carefully designed cross-sectional study. Complete tables and regression formulae to calculate reference ranges and Z scores are presented to use in computer-aided evaluation of fetal ultrasound biometry.

Abdomen↗

PubMed1980

Hematology and biochemistry reference values for female Holstein cattle.

Reference intervals are presented for 14 hematology and 32 biochemistry variables from four age groups of female Holstein cattle (n = 172) selected randomly from six well managed farms. Each animal was examined by a clinician and with the history available considered to be clinically normal at the time of blood collection. The variable observations were examined for outliers and Gaussian distribution prior to parametric or where necessary, nonparametric analysis. Many differences were noted between age groups but few between farms.

Age Factors↗

PubMed1980

Hematology and biochemistry reference values for the light horse.

Reference hematology and biochemistry intervals are presented for a number of variables of clinical interest determined for blood samples obtained from 60 thoroughbred mares, 12 thoroughbred foals and 50 standardbred horses in training. The observations for each variable were examined for outliers and Gaussian distribution. Parametric analysis was used where the observations were Gaussian initially or after any of four transformations, otherwise nonparametric analysis was required for estimation of the 2.5 and 97.5 percentiles. Description of the sample collection procedures, laboratory methods and statistical analysis are available allowing comparison and judicious application of these reference intervals by interested researchers and clinicians.

Animals↗

PubMed1985

[Determination of creatinine in the urine as a reference value of substances excreted by the kidney].

The creatinine excretion is often used as reference value of renally excreted substances. It is usual to perform the creatinine determination according to the Jaffe method. However, since this reaction is influenced not only by the creatinine content but also by other substances it was for orientation tested to which extent adequate incorrect determinations may appear. For this purpose the creatinine content was determined in 28 casual urine specimens in the analysis automation (A) and manually (M) according to the Jaffe method as prescribed in the German Pharmacopoeia 7th ed. D. L. As comparison the enzymatic determination (E) was performed. The determinations according to Jaffe showed too high values. The mean relative percental deviation for the determination in the analysis automation was for (Formula: see text) (variation 6.7 to 94.3%). There were firm correlations between the values of the three determination methods. Since the creatinine determination after Jaffe is the cheapest and most practicable method, in clinical routine work in creatinine-related data of concentration of various renally excreted substances one should realize that in the individual case deviations of the concentration are possible on average up to 50%.

Creatinine↗

PubMed2004

[Study on reference value of healthy teeth mobility of youth].

OBJECTIVE: This study aimed to establish the reference value range of healthy teeth mobility in Chinese youth. METHODS: 200 right side teeth of Han nationality of Chinese youths were measured so as to get the range of the parameters. RESULTS: All parameters of 14 teeth were achieved. The parameter of TM in mandibular incisor was the highest and in mandibular first molar lowest. CONCLUSION: It is very significant to get and quantify the healthy teeth's parameter range. Because they can be served as the healthy contrast when dentists diagnose the mobility. It also reflects the fact that lower the TM parameter is, firmer the tooth will be.

Adult↗

PubMed2000

Reference values for differences between cardio-circulatory variables of normal twin fetuses.

BACKGROUND: No reference values exist concerning the differences between cardio-circulatory variables of normal twin fetuses. The normal data could be useful in the identification of conditions causing opposite hemodynamic effects on each twin. OBJECTIVE: To establish the normal differences among cardio-circulatory parameters of twin fetuses during the second and third trimesters of gestation. MATERIALS AND METHODS: Twenty-seven normal twin pregnancies were used in this longitudinal and prospective study. Doppler-echocardiographic investigations were performed every 2-3 weeks starting at an average of 23.11 +/- 3.13 (mean +/- standard deviation) weeks' gestation. At each visit, the following cardio-circulatory variables were evaluated: the cardio-thoracic ratio, the ventricular wall and septal thicknesses, end-diastolic and systolic diameters, ventricular fractional shortenings, velocity of circumferential fibre shortenings and left and right ventricular outputs. In addition the following measurements were made from Doppler recordings: through both aortic and pulmonary valve the acceleration and ejection times, the peak systolic velocities and the velocity time integrals; and through both mitral and tricuspid valves peak velocities of E and A waves and the E/A ratios. Finally the pulsatility index of the umbilical artery was also evaluated. RESULTS: There was no single variable where the intertwin difference changed with gestational age. No systematic difference between the smaller and larger twin could be demonstrated for any variables except for the cardio-thoracic ratio. CONCLUSION: Reference tables should permit a comparative approach between the two twins in the investigation of life threatening complications such as twin-to-twin transfusion syndrome.

Blood Flow Velocity↗

PubMed2003

Reference values for nocturnal home pulse oximetry during sleep in primary school children.

OBJECTIVE: To provide reference values for pulse oximeter saturation (SpO(2)) in primary school children, measured at home during sleep. METHODS: Recordings of SpO(2) and signal quality from 100 children were randomly selected from a larger population-based sample intended to study the prevalence of sleep-disordered breathing. Recordings were analyzed for the duration of artifact-free recording time (AFRT), minimum SpO(2) (SATmin) and median SpO(2) (SAT(50)), the SpO(2) below which the child spent 5% of AFRT (SAT(5)), and the SpO(2) below which the child spent 10% of AFRT (SAT(10)). In addition, the time in seconds with SpO(2) or= 4% per hour of AFRT (DI(4)), the number of falls in SpO(2) to <or= 90% per hour of AFRT (DI(90)), and the number of falls in SpO(2) to <or= 92% per hour of AFRT (DI(92)). RESULTS: Ten recordings had to be excluded because of insufficient AFRT (< 5 h). Mean age of the remaining 90 children (54 girls) was 9.3 years (SD, 0.6). Median (range; fifth centile) values for SATmin, SAT(5), SAT(10), and SAT(50) were 93% (76 to 97; 87.5), 97% (88 to 99; 95), 97% (89 to 99; 96), and 98% (94 to 100; 97). Median values (range; 95th centile) for TI(90), DI(4), DI(90), and DI(92) were 0.0 s (0.0 to 5.8; 1.6), 0.8 (0.0 to 6.1; 3.9), 0.0 (0.0 to 1.2; 0.2), and 0.0 (0.0 to 2.0; 0.6). CONCLUSION: Baseline SpO(2) values < 97% were uncommon in these children, as were intermittent desaturations to <or= 90%. These data may serve as a basis for the interpretation of clinical recordings of SpO(2) in children referred for sleep-related breathing disorders.

Child↗

PubMed2003

Development of a microplate ELISA for circulating E-selectin: assay characterization, comparison with a commercial kit, wand establishment of normal reference values.

E-selectin, an adhesion molecule, is detectable in the blood. Serum levels of E-selectin can be a prognostic indicator for various malignancies. We developed a microplate enzyme-linked immunosorbent assay (ELISA) for the detection of circulating E-selectin by coating the microwell with monoclonal anti-E-selectin. We incubated the specimen and the biotinylated detecting antibody simultaneously, and used HPR-conjugated streptavidin to generate a signal for quantification. The assay has a sensitivity of 3.8 ng/mL, and the coefficients of variation (CVs) for both within-day and day-to-day precision were all <10%. Our in-house-made kit also compared well with a commercial kit from R&D Systems (r=0.95, slope=0.94). Using our kit we determined a normal reference value for Chinese individuals of different ages (30-80 years). We found no significant difference between females and males; however, age appeared to have an impact on the normal E-selectin value. We found that normal individuals over 60 years old had higher levels of circulating E-selectin (65.8+/-19.5 ng/mL, N=111) compared to those under 60 years old (59.5+/-18.1 ng/mL; P=0.002). Our kit appears to have sufficient sensitivity for detecting elevated circulating E-selectin in various carcinomas. We believe that with the established normal reference value, our in-house-developed ELISA kit is well suited for routine clinical laboratory use.

Adult↗

PubMed1994

Reference values of motor unit action potentials obtained with multi-MUAP analysis.

We collected reference values of motor unit action potentials (MUAPs) from healthy deltoid, brachial biceps, first dorsal interosseous, lateral vastus, and anterior tibial muscles in 105 subjects between 15 and 86 years. The MUAPs were recorded with a concentric needle electrode and extracted with a decomposition method we call multi-MUAP analysis. The main goal is to identify and extract MUAPs. Also, the firing pattern of the motor units can be followed. No significant changes with age were found for duration, spike duration, thickness, amplitude, area, size index, or number of phases in all muscles studied. We did not find any influence of gender or height. We found higher amplitudes and shorter durations compared with previous studies. This may be due to a higher contraction level that can be used with a decomposition technique. No right-left side differences were found. The coefficient of variation of the parameters in repeated examinations was small, which implies a good reliability of the measurements. Interexaminer variability of four investigators was not greater than in repeated studies.

Action Potentials↗

PubMedDate not supplied

Modelling the lung function of Caucasians during adolescence as a basis for reference values.

BACKGROUND: In childhood the relationship between lung size and stature changes during the adolescent growth spurt. This is not allowed for in models of lung function based on stature alone. For spirometric indices inclusion of an age x stature interaction (A x St) can overcome the difficulty. AIM: The study tested the hypothesis that this simple, interactive model might also be effective for total lung capacity and its subdivisions and the single breath transfer factor for carbon monoxide. SUBJECTS AND METHODS: Data were available for 695 asymptomatic non-smokers (Caucasians) aged 7-20 years (440 boys, 255 girls). Each lung function index was described using the above model and the fit was compared with that from a linear, power or polynomial model based on stature alone. RESULTS: After allowing for stature, the A x St interaction term was significant for almost all indices. The improved fit was most apparent for the lung function of older adolescent boys. Reference values using the model are reported. CONCLUSIONS: A simple model based on stature and an interaction between stature and age can account for the changing relationship between body habitus during the growth spurt and lung size and transfer factor in a single equation encompassing children and adolescents. Its use is recommended for deriving reference values when the explanatory variables are limited to stature and age.

Adolescent↗

PubMed1995

Estimation of reference values for urinary 1-hydroxypyrene and alpha-naphthol in Danish workers.

In order to assess environmentally and occupationally related exposures to PAH compounds it is essential to have reference or normal values in human body fluids. The establishment of reliable reference intervals is an absolute pre-requisite in determining relationships between internal PAH exposure in humans and health effects in occupationally exposed workers. In this context the estimation of the biological level of PAH metabolites in urine from reference populations has become increasingly important in the field of environmental and occupational toxicology. The present study describes the calculation of tentative reference values for urinary 1-hydroxypyrene on the basis of two reference populations and for urinary alpha-naphthol on the basis of one reference population in accordance with IFCC recommendations. The study subjects were 115 healthy male workers occupationally exposed to PAH at low levels and 121 reference subjects non-occupationally exposed to PAH. Tentative reference values for urinary 1-hydroxypyrene were estimated. In addition, 236 healthy male workers were used to estimate tentative reference values for urinary alpha-naphthol. The reference populations were described by distribution free one-sided tolerance intervals. The 95% one-sided tolerance limit calculated for 1-hydroxypyrene in urine was 0.053 mumol/mol creatinine for non-occupationally exposed individuals and 0.169 mumol/mol creatinine for low level PAH exposed workers, with the coverage interval (95 +/- 4.5) percent at a probability of 0.95. Thus, the probability was 0.975 that the tolerance interval included at least 90.5% of the distribution. In addition, the probability was 0.025 that the tolerance interval included > 99.5% of the population. The tolerance interval for alpha-naphthol in urine was 5.665 mumol/mol creatinine with the coverage interval (95 +/- 4.5) percent at a probability of 0.95.

Air Pollutants, Occupational↗

PubMed1990

Trace element reference values in tissues from inhabitants of the European community. I. A study of 46 elements in urine, blood and serum of Italian subjects.

Neutron activation analysis-electrothermal atomic absorption spectroscopy (ETA-AAS) and inductively coupled plasma atomic emission spectrometry (ICP-AES) have been used for the determination of 46 elements in urine, 35 in blood and 26 in serum of unexposed Italian subjects living in the same region (Lombardy). The results allowed the proposal of reference values for various elements determined in more than 350 healthy subjects, these being Ag, Al, As, Be, Bi, Cd, Co, Cr, Cu, Hg, Mn, Ni, Pb, Sb, Se, Tl, V, Zn, in urine; Ag, As, Bi, Cd, Cr, Co, Cu, Hg, Pb, Se, Tl, Zn in blood; and Ag, Al, Be, Cd, Co, Cr, Cu, Hg, Mn, Ni, Pb, Se, Tl, V, Zn in serum (or plasma). For all other elements indicative values are suggested. In addition to the mean value and the "reference range", a "range of uncertainty" and an upper limit above which metabolic abnormalities could be expected have also been defined on the basis of simple statistical considerations.

Humans↗

PubMed2006

Reference values for serum protein and electrolyte study from Rwanda.

OBJECTIVE: To estimate reference values of serum proteins and electrolytes in a student population in Butare, Rwanda (altitude: 1768 m; barometric pressure: 629 mm Hg). DESIGN: A laboratory based cross-sectional study. SETTING: The units of physiology and clinical chemistry, department of medical biology, Butare University Hospital and Faculty of Medicine, National University of Rwanda, from February 2002 to May 2003. SUBJECTS: Young healthy adults were selected randomly from the students of the National University of Rwanda, using Epi-Info 6.04 software. RESULTS: The results mean and reference range (2.5th-97.5th percentile) in brackets - are as follows: total proteins: male: 7.3 (6.3-8.4) g/dL, female: 7.3 (6.5-8.5) g/dL; albumin: male: 4.3 (3.1-5.2) g/dL, female: 4.1 (3.2-5.0) g/dL; globulins: male: 3.1 (2.0-4.2) g/dL. female: 3.2 (2.1-4.2) g/dL; sodium: male: 138.5 (130-147) mmol/L, female: 139.8 (132-153) mmol/L; potassium: 4.0 (3.1-5.0) mmol/L both in male and in female; chloride: males: 104.4 (96-112) mmol/L, females: 106.1 (98-114) mmol/L; phosphates: male: 1.13 (0.65-1.59) mmol/L, female: 1.17 (0.71-1.52) mmol/L. CONCLUSION: The values of serum proteins and electrolytes are comparable to classical sea level values; however there is a slight increase in serum chloride.

Adult↗