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PubMed2002

Reference values for ductus venosus Doppler flow measurements at 10-14 weeks of gestation.

OBJECTIVES: To calculate reference ranges for ductus venosus Doppler measurements obtained transabdominally at 10-14 weeks of gestation. DESIGN: Two hundred and one normal fetuses with a crown-rump length (CRL) ranging from 38 to 88 mm were examined in a cross-sectional study. The pulsatility index for veins (PIV), peak velocity during ventricular systole (S-wave), lowest forward velocity during atrial contraction (A-wave) and time-averaged maximum velocity (TAMXV) were recorded from the ductus venosus. Flow velocity waveforms were also classified as normal or abnormal according to the presence (normal) or absence or reversal (abnormal) of frequencies during atrial contraction. RESULTS: Three of 201 fetuses showed an abnormal flow pattern (1.5%; 95% exact confidence interval, 0.3-4.3%). In the 198 fetuses with a normal flow pattern, the mean PIV ranged from 1.07 at a CRL of 38 mm to 1.00 at a CRL of 88 mm (r = -0.093; P = 0.19). A significant increase in mean blood flow velocity with increasing CRL was noted for the S-wave (27.0 cm/s to 33.6 cm/s; r = 0.17; P = 0.02), the A-wave (5.9 cm/s to 7.8 cm/s; r = 0.14; P = 0.04) and the TAMXV (19.4 cm/s to 25.3 cm/s; r = 0.19; P < 0.01). Crown-rump length-specific reference ranges for each parameter were calculated using the method of scaled absolute residuals. CONCLUSIONS: Abnormal ductus venosus flow patterns could be observed in normal fetuses, even if they ocurred with a low prevalence. Reference values for Doppler measurements were established in fetuses with normal patterns of flow.

Blood Flow Velocity↗

PubMed1986

Determination of aluminium in human tissues by flameless atomic absorption spectroscopy and comparison of reference values.

Aluminium in human tissues has been determined by flameless atomic absorption spectroscopy (AAS). Tissues were dried at 110 degrees C and digested with concentrated nitric acid at 50 degrees C overnight. After dilution with distilled water the samples were measured. The aluminium levels of the controls (healthy individuals who died as a result of an accident) appeared to be: grey matter 2.1 +/- 1.0 (mean +/- SD), white matter 1.7 +/- 0.5, spinal cord, 3.3 +/- 1.5, kidney 1.9 +/- 0.7, heart 2.1 +/- 1.1, vertebral cortex 1.9 +/- 1.8, and vertebral trabeculae 3.1 +/- 1.8 micrograms/g dry weight. For a patient with dialysis motor neuropathy significantly higher values were found. Comparison with values in the literature shows that our reference values are in agreement with published results obtained by flameless atomic absorption spectroscopy.

Aged↗

PubMed1990

Comparisons of spirometric reference values and the proportions of abnormal subjects among male smokers and those symptomatic in a community population.

A comparison was performed of various population reference equations for several spirometric measurements. The objective was to determine if the different equations yielded similar distributions of the percent predicted values, similar reference values for asymptomatic nonsmokers (i.e., normal subjects), criteria (or cutoff points) for who might be defined statistically as normal, and similar proportions of smokers and symptomatic subjects who would fall below the criteria values and thus be considered statistically abnormal. The cross-sectional study population of adults in Tucson, subjects of an ongoing study, was used. Most of the equations yielded reasonably similar distributions of percent predicted values. Older and/or more unusual equations did not yield similar results. Using the lower 95th percentile criteria yielded similar cutoff points as reference values for statistical normality, and similar proportions of statistically abnormal among various smoking and symptomatic groups; some of the equations used did not. When the criteria used were the lower 1.645 SEE, or the published criteria, the proportions considered statistically abnormal were very low or very high; again, some equations gave very disparate results. The first conclusion was that the use of the lower 95th percentile criteria was more sensitive and specific. It was concluded also that most equations yield sufficiently similar results such that the choice of reference equation from those available would depend on other criteria.

Adult↗

PubMed2001

Determination of serum cystatin C: biological variation and reference values.

Human cystatin C is a low molecular weight protein which has been proposed as a better marker of glomerular filtration rate than creatinine. To be able to interpret results obtained in different patient populations it is necessary to define cystatin C reference values. We measured serum concentration of cystatin C in 1223 subjects using a particle-enhanced nephelometric assay. Subjects were aged 4 to 79 years and were selected among apparently healthy individuals who came to the Centre for Preventive Medicine in Vandoeuvre-Lès-Nancy, France. We observed a Gaussian distribution of cystatin C concentration in serum. We did not find any effect of age or gender in children, hormonal status in women (puberty, menopause, oral contraceptives or hormone replacement therapy) or alcohol intake. Cystatin C concentration was slightly lower in female than in male adults below the age of 60 years. Cystatin C levels significantly increased above the age of 60 in both males and females, probably due to physiological aging of renal function. No other significant differences were observed between males and females. Using multiple regression analysis, moderate correlations were observed between body mass index and cystatin C, and between smoking and cystatin C, but these were not biologically significant. According to the literature, only methylprednisolone and cyclosporin A increased and decreased cystatin C levels, respectively. The reference values for cystatin C obtained in a carefully selected population were 0.75+/-0.089 mg/l for children aged 4-19 years, 0.74+/-0.100 mg/l for males and 0.65+/-0.085 mg/l for females (aged 20-59 years), and 0.83+/-0.103 mg/l for older individuals (> or =60 years).

Adolescent↗

PubMed1989

[Fundamental studies, reference values and relationship to menstrual cycle of prolactin RIA BEAD II].

We have tried fundamental studies, reference values and relationship to menstrual cycle on Prolactin RIA BEAD II kit which has a method of IRMA using monoclonal antibody. On clinical studies, we investigated change of serum prolactin level during the menstrual cycle and relationship to other hormones (LH, FSH, estradiol, progesterone). It was the result that prolactin level of follicular phase was lower than that of preovulatory phase and luteal phase. We conclude that change of prolactin level during the menstrual cycle is related with change of estradiol level.

Adult↗

PubMed2004

[Study of normal reference values for bone mineral contents in children and adolescents in Beijing].

OBJECTIVE: The paper aims to provide reference values of bone mineral content for school-age children and adolescents in Beijing. METHODS: Normal values for total body bone mineral content (TBMC) were derived from measurements on 1025 children and adolescents aged from 6 to 18 years in Beijing city, and bone mineral content (BMC) values for selected regions of interest were also presented, including head, chest, midriff, pelvis, legs and arms. Both BMC and body mineral density were determined by dual-energy x-ray absorptiometry (DEXA). RESULTS: The results revealed that bone mineralization increased gradually in early childhood and accelerated during adolescence and there were significant age and gender effects on all regions of interest as well as total body. TBMC in 18 year group was about 3 and 2.7 times more respectively for male and female than that in 6 year group, and female's increasing trend flat at the age of 14, while male TBMC keep growing until 17. Legs contribute much more to the increase of TBMC than other regions. Compared with white-origin children, the subjects were bestowed with more TBMC but less TBMD. CONCLUSION: BMC depends on sex, age, region and race. The normal values can be used to the assessment of bone status for children and adolescences to serve clinical as well as research purposes.

Absorptiometry, Photon↗

PubMed1976

Single-breath pulmonary diffusing capacity. Reference values and application in connective tissue diseases and in various lung diseases.

1.1. Diffusing capacity of the lungs was measured by using a Mark 4 Resparameter. The single-breath diffusing capacity (D) for carbon monoxide was found to be dependent on the lung volume (VA) during the breath-hold. The same applied to D/VA and to the time constant (tau) for carbon monoxide uptake. This confirms the theoretical considerations and the results of other investigators. This effect should be taken into account especially when making serial determinations of D on the same subject. 1.2. The repeatability of the method was found to be reasonably good; the coefficient of variation was about 4% in normal subjects, as well as in a series of patients with rheumatoid arthritis. 1.3. The effect of the correction for haemoglobin concentration was calculated and tabulated for a set of possible values of DM/Vc and haemoglobin. This correction did not reduce the scatter of D values in normal subjects, but it was adopted for clinical use for theoretical reasons. Caution in its use and interpretation of the correction is emphasized. 2.1. Healthy males and females, 20-69 years of age, were examined to establish reference values for the D measurement. Multiple linear regression equations were calculated stepwise, and equations based on age and height were then used in the clinical prediction equations. Similarly, prediction equations were calculated for clinical spirometry. 2.2. The prediction equations were compared with some published reference values. The equations provide a basis for the evaluation of the effect of various factors, such as age and smoking, in different populations. 3.1. Respiratory function, clinical symptoms and chest x-ray findings were examined in patients with connective tissue diseases. Three different investigations were thus formed: a) consecutive patients (free of lung disease other than that possibly due to a connective tissue disease) with definite rheumatoid arthritis (RA, 21 cases), systemic lupus erythematosus (SLE, 18 cases) or scleroderma (SCL, 6 cases) were subjected to detailed tests. b) 129 patients from the Rheumatism Foundation Hospital, Heinola, Finland, were subjected to measurement of diffusing capacity and vital capacity in addition to chest radiography and routine clinical assessment c) the histological findings on 12 patients subjected to a needle biopsy of the lung in order to exclude other conditions were compared with the results of diffusing capacity and x-ray examinations. 3.2. Restrictive impairment of the respiratory function was the general finding in all of these groups. The reduction in diffusing capacity was out of proportion to the reduction in lung volume, however, in most cases with abnormally low values. Low D values were encountered in about half of the RA and SLE and in all of the SCL patients in group a, and in 13% of the "average" RA patients studied in Heinola. The typical histological finding in patients with reduced D was a thickening of the alveolar wall...

Adult↗

PubMed2002

Age-related reference values for serum selenium concentrations in infants and children.

BACKGROUND: Children are at particular risk for selenium deficiency, which has potentially serious medical implications. Reliable age-specific reference values for serum selenium concentrations in children are sparse, but are essential for the identification of selenium deficiency and decisions regarding selenium supplementation. METHODS: Using electrothermal atomic absorption spectrometry, we analyzed serum selenium concentrations from 1010 apparently healthy children (age range, 1 day to 18 years) and from 60 patients on a protein-restricted diet because of inborn errors of metabolism. Reference intervals were defined according to recommended guidelines. RESULTS: Medians for serum selenium concentrations showed a statistically significant age dependency: a decrease from the age <1 month (0.64 micromol/L) to 4 months (0.44 micromol/L); an increase to 0.62 micromol/L in the 4-12 months age group; constant values in children between 1 and 5 years of age (0.90 micromol/L); and an additional slight increase to reach a plateau between 5 and 18 years (0.99 micromol/L). Of 43 children older than 1 year and on a protein-restricted diet, 87% showed serum selenium concentrations below the 2.5 percentile. CONCLUSIONS: Because of nutritional changes, serum selenium concentrations are significantly higher in older children than in infants under 1 year of age. The application of age-adjusted reference values may provide more specific criteria for selenium supplementation. Long-term protein restriction in children is reflected by a failure to achieve higher serum selenium concentrations with increasing age.

Adolescent↗

PubMed2004

A new quality control method based on a moving average of "latent reference values" selected from patients' daily test results.

The average of normals(AON) method is a quality control(QC) method that uses measured values of patients' samples instead of QC samples. Because this method is easily affected by fluctuations in the patient population and is insensitive to short-term changes in test values, we developed an alternative method based on the moving average(MA) of latent reference values(LRVs) which are the test results of patients whose other related test results are all within reference intervals. We evaluate the new methodology(MALRV) using seven commonly measured biochemical tests. The LRV of each test were selected with reference to four other items that had the highest coincidences of abnormality. The optimum amount of data needed to compute the MA is determined as that making the coefficient of variation(CV) of the consecutive MA over a study period less than 5.0%. The MALRV is computed each time a new LRV is encountered to monitor quality status continuously. The MALRV CV was within 5.0% when sample sizes were between 20 and 110. When shift and trend simulations were performed with the patient data, the corresponding alterations were detected. MALRV is a useful measure for detecting short-term alterations in patient test results, supplementing the conventional QC chart method.

Clinical Laboratory Techniques↗

PubMed1990

[Reference values for cortisol, T4 and T-uptake in different horse groups using the fluorescence polarization immunoassay (FPIA)].

Reference values for Cortisol, T4 and T-Uptake, determined with the Fluorescence-Polarization-Immunoassays (FPIAs) in blood-plasma of different horse groups were established. The highest Cortisol values were measured in blood samples from thoroughbred racehorses and riding horses taken between 7 and 8 a.m. (181 +/- 37 and 268 +/- 43 nmol/l), the lowest gained between 5 and 6 p.m. (69 +/- 45 and 85 +/- 32 nmol/l respectively). Peak values for T4 in riding horses were found in blood samples collected between 1 and 2 p.m. (28.2 +/- 5.7 nmol/l) followed by the samples taken at 5-6 p.m. and 7-8 a.m. T-Uptake values did not show a diurnal variation. Values of thoroughbred racehorses were much lower than in thoroughbred broodmares and riding horses (0.11 +/- 0.03, 0.18 +/- 0.03 and 0.24 +/- 0.05 units). The blood samples collected on 5 successive days showed significant variations for Cortisol. T4-values were stable whilst T-Uptake had small variations.

Animals↗

PubMed1989

[Fundamental examination and the reference values of anticardiolipin antibodies].

We studied sera from 146 healthy individuals in a fundamental examination to obtain reference values for anticardiolipin antibodies by the enzyme-linked immunosorbent assay (ELISA). The good results were obtained in the evaluation of concentrations of pretreatment substances, cardiolipin antigen and serum samples, as well as in reproducibility and stability on the storage of the samples. However, there was interference by triglycerides, hemoglobin and birilubin. The O.D. values and positive values of IgG, IgA and IgM in healthy individuals were 0.105, 0.111, 0.173 and 4.1%, 2.7%, 2.7% respectively. Furthermore, the incidences of anticardiolipin antibodies in systemic lupus erythematosus, mixed connective tissue disease, progressive systemic sclerosis, Sjogren's syndrome, polymyositis/dermatomyositis, rheumatoid arthritis, unclassified connective tissue disease, polyartertis nodosa and idiopathic thrombocytopenic purpura were 48.0%, 40.0%, 50.0%, 21.4%, 26.3%, 29.4%, 40.0% and 25.0% respectively. Especially, the incidence of IgG antibody against cardiolipin was high. Detection of phospholipid cardiolipin antibodies using ELISA was considered to be a useful for clinical diagnosis and monitoring of patients with systemic lupus erythematosus and associated autoimmune disorders.

Autoimmune Diseases↗

PubMedDate not supplied

Alpha 1-fetoprotein (AFP) reference values in infants up to 2 years of age.

The aim of this study was to establish reference values and factors associated with serum AFP elevation in infants. Five hundred twenty-four samples collected from infants up to the age of 2 years at the University Hospital Düsseldorf (Germany) were analyzed. At birth mean serum AFP levels were 41,687 ng/ml in 256 term babies and 158,125 ng/ml in 90 premature babies born before the 37th gestational week, excluding samples from children with factors known to be associated with AFP elevation. In the first 4 weeks of life, AFP levels decreased by 50% in 5.1 days in term babies. Between day 180 and 720 of life, AFP levels up to 87 ng/ml were within the 95.5% interval (assumed logarithmic normal distribution) with a mean of 8 ng/ml without a further decline. By the age of 2 years the infants of this study had not reached adult serum AFP levels (0-6 ng/ml).

Female↗

PubMed2001

Developing an expert system for immunophenotypical diagnosis in immunodeficiency. Age-related reference values of peripheral blood lymphocyte subpopulations in Hungary.

In the process of developing a decision support system based on flow cytometric data for the diagnosis of immunodeficiency, assessment of lymphocyte subpopulations in human peripheral blood provides the key for further analysis. Samples from 273 'healthy' Hungarian subjects were measured between 1998 and 1999. Immunophenotypic data are compared here (unadjusted for gender) by different age groups: I 0-6 years (n=45); II 7-18 years (n=71); III 19-35 years (n=72); IV 36-55 years (n=48); and V 56-99 years (n=37). Two-color flow cytometric analysis was performed using the Becton Dickinson Simultest IMK Plus kit (CD45/CD14, isotype control, CD3/CD19, CD4/CD8, CD3/HLA-DR, CD3/CD16+56). All lymphocyte subpopulations were measured in all blood samples identically. The quality criteria involved at least 95% of total lymphocytes in the analysis gate, homogenous CD45+ lymphocyte population (minimum of 2000 events in the gate, CD45+ >95%). The frequency of B lymphocytes was the highest, significantly, in the youngest Hungarian subjects, but there were no significant changes with age comparing the data of other II-V age groups. On the other hand, some T subpopulations changed with aging; both CD4 and CD8 subsets varied over time including the elevation of the fraction of activated T cells as well as LGL-NK cells. Some of these changes were significant by statistical tests. Interpretation of flow cytometric data is time-consuming and requires human knowledge of an expert laboratory staff. To facilitate the diagnosis of immunodeficiency, a pilot study aiming at the development of a diagnostic algorithm has been initiated. Algorithm nodes compare the frequency of each lymphocyte subpopulations to the generated reference values. This knowledge-based system describes a short summary report as a result of the comparison, and points to some values requiring further human examination to reach a final conclusion. These reference values and the expert system appear to be a recommended basis for comparing and combining results from different laboratories.

Adolescent↗

PubMed2005

Health-related quality of life measured by the UW-QoL--reference values from a general dental practice.

The objective of this study was to obtain age and sex-specific reference values for the University of Washington head and neck cancer questionnaire version 4 (UW-QoLv4) and to compare this with patients with oral and oropharyngeal cancer. Cross-sectional reference data was collected from 372 patients in six local general dental practices, 349 of whom presented for routine appointments. Quota sampling was used to collect data for similar numbers of patients by gender by four age bands (40-49, 50-59, 60-69, 70-79 yr). The longitudinal sample consisted of 450 consecutive patients undergoing primary surgery for previously untreated oral and oropharyngeal squamous cell carcinoma presenting to the Regional Maxillofacial Unit Liverpool, between the years 1995 and 2002. At baseline the key differences were anxiety, pain, swallowing, chewing, and mood. At 1yr there were big differences in all domains with deterioration in the oral cancer group. The difference was least notable in pain, shoulder, mood and anxiety. Reference data from a non-cancer population is very important when considering UW-QoL domains as an outcome parameter in clinical trials and also when discussing health-related quality of life outcomes with patients and their families.

Adult↗

PubMed2004

Plasma biochemistry reference values of wild-caught southern stingrays (Dasyatis americana).

Stingrays are prominent marine animals; however, there are few published reference values for their blood chemistry and hematology. Twenty-eight southern stingrays (Dasyatis americana) were caught using the bottom trawl nets of fishery-independent boats operated by the South Carolina Department of Natural Resources during June and July 2002 from Winyah Bay, South Carolina, to St. Augustine, Florida. Median values of blood and plasma obtained from live animals promptly after capture are as follows: packed cell volume = 0.22 L/L (22%), total solids (TS) = 56.5 g/L (5.65 g/dl), total protein (TP) = 26 g/L (2.6 g/dl), sodium = 315 mmol/L, potassium = 4.95 mmol/L, chloride = 342 mmol/L, calcium = 4.12 mmol/L (16.5 mg/dl), phosphorus = 1.5 mmol/L (4.7 mg/dl), urea nitrogen = 444 mmol/L (1,243 mg/dl), glucose = 1.69 mmol/L (30 mg/dl), aspartate aminotransferase = 14.5 U/L, creatine phosphokinase = 80.5 U/L, osmolality = 1065 mOsm/kg, and lactate = 3.1 mmol/L. Bicarbonate was less than the low end of the instrument range (5 mmol/L) in all but three samples. Anion gap was negative in all samples. Albumin was less than the low end of the instrument range (1 g/dl) in all except one sample. Osmolality was significantly higher in the rays caught in the southern region. TS and TP values were linearly related to each other, and the equation for the fitted line is TS = (11.61 x TP) + 25.4 (in g/L) [or TS = (1.161 x TP) + 2.54 (in g/dl)]. The reference ranges reported in this study can be used to aid in the management of aquarium stingrays and to create a baseline for health monitoring of the wild Dasyatis spp.

Acid-Base Equilibrium↗

PubMed1983

[alpha 2-Macroglobulin in serum and plasma: reference values with carbobenzoxy-valyl-glycyl-arginine-p-nitroanilide, a chromogenic substrate].

alpha 2-Macroglobulin can be determined using the amidolytic activity of the alpha 2-macroglobulin-trypsin-complex. Reference values are reported using a commercially available kit for continuous assay at 25 degrees C. Reference ranges obtained in a population of 235 children and adults aged between 1 day and 61 years were found to be age-dependent. Reference ranges established for the different age groups of children were grouped together in order to obtain useful guide values. The following values were obtained for serum: 1 to 10 days: 5-11 kU/l 11 days to 18 years: 8-16 kU/l The reference values (5th to 95th percentile) determined for juveniles and adults were as follows: 19 to 25 years: 4.1-12.2 kU/l (serum); 4.0-11.2 kU/l (citrated plasma) greater than or equal to 25 to 61 years: 4.1-8.1 kU/l (serum); 3.7-7.4 kU/l (citrated plasma) No variation according to sex was observed, nor was any difference noted between preprandial and postprandial catalytic concentrations, or between values in smokers and non-smokers or between values in the group of women taking hormonal contraceptives and the group not taking such drugs. If the dilution of the blood sample with citrate solution is taken into account when calculating the catalytic concentrations in citrated plasma, the values in plasma are higher than those in serum (median 11%). Measurement of the alpha 2-macroglobulin-trypsin complex in plasma is assumed to give a more realistic reflection of the in vivo activity than measurement in serum. Comparison with two immunological methods (radial immunodiffusion and kinetic nephelometry) revealed that there is a linear relationship between the measurement of the catalytic concentration of the alpha 2-macroglobulin-trypsin complex and the immunological concentration of alpha 2-macroglobulin. Therefore mutual conversion is possible for the described concentration range.

Adolescent↗

PubMed1996

A reference value for delta-aminolevulinic acid in plasma in the population occupationally unexposed to lead.

To obtain a reference value for delta-aminolevulinic acid in plasma (ALA-P), we determined ALA-P levels in 141 subjects (105 males and 36 females) without occupational exposure to lead. The distribution of ALA-P levels in males can be regarded to follow log-normal distribution and the geometric mean was 8.7 micrograms/l with 95% confidence interval of 6.0-12.5 micrograms/l. These data would be useful as a baseline for evaluating the relationship between ALA and its biological effects.

Adult↗

PubMed1999

Plasma lipids and lipoprotein reference values, and the prevalence of dyslipoproteinemia in Canadian adults. Canadian Heart Health Surveys Research Group.

OBJECTIVE: To report reference values for plasma lipids and lipoproteins in Canadian adults and the prevalence in the population of various levels of risk for coronary artery disease from dyslipoproteinemia. DESIGN, SETTING AND PARTICIPANTS: Population- based provincial heart health cross-sectional surveys in 10 provinces between 1986 and 1992 invited 29,855 men and women aged 18 to 74 years to participate. During a clinic visit after a home interview a blood sample was obtained following a fast of 8 h or more from 18,555 people. Plasma lipid levels were determined at the J Alick Little Lipid Research Laboratory, Toronto, with standardization of the Centers for Disease Control Lipid Standardization Program, Atlanta. OUTCOME MEASURES: Fasting plasma total cholesterol, triglyceride, low density lipoprotein cholesterol (LDL-C), high density lipoprotein cholesterol (HDL-C) and non-HDL-C levels. MAIN RESULTS: Mean plasma total cholesterol, LDL-C, non-HDL-C and triglyceride levels increased with age in men to a peak at around age 54 years, while in women the increases were more gradual at a lower level until age 54 years, after which they increased appreciably eventually exceeding values for men. A high percentage of adults were at increased risk for coronary artery disease: 44% had elevated total cholesterol levels above 5.2 mmol/L; 14% had LDL-C levels above 4.1 mmol/L; 8% had HDL-C values below 0.9 mmol/L; and 14% had triglyceride levels above 2.3 mmol/L. Eleven per cent of adults had both total cholesterol level above 6.2 mmol/L and LDL-C level above 4.1 mmol/L. CONCLUSION: The high prevalence of Canadian adults at risk because of elevated plasma lipid levels strongly indicates the need for comprehensive public health programs to reduce plasma lipid levels in the population and the need to encourage physicians to treat those at high risk.

Adult↗