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PubMed1984

Reference values for serum components in pregnant women.

Reference values have been collected for 11 chemical blood serum components during the three trimesters of pregnancy in 100 healthy pregnant women. The results used for reference intervals are presented as 2.5, 50 and 97.5 percentiles. Especially regarding S-Albumin, S-Alkaline phosphatase and S-5'-Nucleotidase the changes were most pronounced during the third trimester. S-Gammaglutamyl-transferase did not change significantly during pregnancy. For S-Aspartate aminotransferase and S-Alanine amino-transferase there were no significant changes in the mean values during the three different trimester periods. In the third trimester the frequency distribution of the enzymes became skewed to the right, i.e. in some women the enzyme activities increased noticeably more than in others. S-Na showed a significant decrease even during the first trimester and this lowering was slightly more pronounced during the second and third trimesters. S-Ca decreased in parallel with S-Albumin concentration. The changes in S-CaAlbumin-corrected were distinctly smaller than those in S-CaTotal. Throughout pregnancy, S-K, S-Bilirubin and S-Thymol turbitidy test values did not deviate from non-pregnant levels.

Adolescent↗

PubMed2000

[Reference values for hematologic laboratory tests and hematologic disorders in the aged].

The establishment of reference values in the complete blood count and lymphocyte subsets for the aged is necessary for diagnosis and therapy since the number of the aged is increasing rapidly in recent years. However, it is problematical to define the healthy aged because of physiological changes with aging, compared with the healthy adults. Red blood cell count, hemoglobin concentration(Hb) and hematocrit for the healthy aged showed the tendency of moderate decreasing with aging. These phenomena become more obvious by dividing the healthy aged into three groups, 65-74 years, 75-84 years and over 85 years. The mean corpuscular volume(MCV) for the healthy aged showed the tendency of increasing with aging, while mean corpuscular hemoglobin and mean corpuscular hemoglobin concentration for the healthy aged showed no tendency with aging. No changes for the healthy aged were observed in the leukocyte differential, white blood cell count and platelet count with aging. Results of lymphocyte subsets(CD3, CD4, CD8, CD19 and CD4/CD8 ratio) for the healthy aged are not coincident among reporters at present because the healthy aged population is different and the determination of lymphocyte subsets is not standardized. It is important to diagnose as anemia below Hb 11.0 g/dL between 65 and 74 years, Hb 10.0 g/dL over 75 years using Hb level with high accuracy. Most of hematologic disorders in the aged are the secondary anemia based on malignant tumor. In the aged between MCV 95 and 120 fL or over MCV 120 fL, myelodysplastic syndrome or vitamin B12 deficiency is considered, respectively. In the future, more vertical study in the aged population is needed to establish the reference values for the aged.

Adult↗

PubMed2000

Echocardiography, color-coded Doppler imaging, and abdominal sonography, a non-invasive method for investigation of heart and aortic morphology and function in female gottingen minipigs: method and reference values for M-mode, B-mode, and flow parameters.

OBJECTIVE: The aim of the study reported here was to set up a method for echocardiography (EC) and abdominal sonography and to obtain EC reference values for left ventricular (LV) morphology and function and sonographic abdominal aortic morphology, function, and flow values in conscious, unsedated Gottingen minipigs. METHODS: Applying a standardized investigation procedure, the following parameters were measured by use of M-mode EC, color-coded Doppler imaging, and B-mode sonography, or were calculated, in 58 female minipigs: LV end-diastolic and end-systolic diameter, interventricular septum thickness, LV caudal wall thickness, LV end-diastolic volume and end-systolic volume, fractional shortening, ejection fraction, and percentage of thickening of interventricular septum and LV caudal wall. In addition, morphology, pulsatility, flow values, and flow patterns in the abdominal aorta were recorded or calculated during abdominal sonography and color-coded Doppler imaging. RESULTS: Variable EC values were obtained due to individual variations of motor activity. Variation could be reduced by accustoming the animals to a standardized investigation procedure. Reference values could be obtained for EC, partially indicating clear correlation with body weight. Color-coded Doppler and Doppler spectra did not indicate flow disturbances in large arterial abdominal vessels. CONCLUSIONS: Results indicate that handling during EC and sonography can cause discomfort in unsedated minipigs that may interfere with recording of valid reference values for functional cardiac parameters in young animals. Accustoming the animals to a standardized investigation procedure reduces stress to a satisfactory level and enables data recording. Thus the minipig is considered suitable for assessment of cardiovascular parameters in experimental or toxicologic studies.

Animals↗

PubMed1999

Reference values of facial features in Scandinavian children measured with a range-camera technique.

Reference values of facial features in white Scandinavian children were ascertained using a newly developed range-camera technique with a three-dimensional measuring program specifically designed for anthropometric measurements. Seven facial features in 613 healthy subjects (322 girls, 291 boys), aged 1 month to 18 years, and nine subjects with the fetal alcohol syndrome,aged 7 to 18 years, were studied. Data were analysed by multivariate multiple regression and measurements of each facial feature plotted against age and presented as curves, with 95% and 99% univariate prediction limits. All children with fetal alcohol syndrome had shorter palpebral fissures, and in six of them the outer canthal distance was shorter than that in the reference group. The reference values presented may be useful in clinical practice--for example, in the evaluation of children with syndromes that result in dysmorphology of the face and in the planning of plastic and reconstructive surgery.

Adolescent↗

PubMed2004

Design of internal quality control for reference value studies.

Internal quality control should assure that the desired quality goals are achieved during reference value studies. Quality goals are often stated in the form of allowable limits of error, such as an allowable total error or an allowable bias. For reference value studies, it may be more appropriate to utilize a goal for allowable bias. In either case, it is possible to calculate a metric in the form of the critical systematic error that can be used to guide selection or design of the internal quality control procedure. A graphical tool, called the critical-error graph, facilitates the selection by superimposing the calculated critical systematic error on the power curves of different control rules and numbers of control measurements. Examples are provided to illustrate the calculation of the critical systematic error from both an allowable total error goal and an allowable bias goal, using figures from an extensive tabulation of available total error and bias goals.

Bias↗

PubMed2000

Cerebrospinal fluid protein concentration in pediatric patients: defining clinically relevant reference values.

OBJECTIVES: To define clinically relevant reference ("normal") values for cerebrospinal fluid (CSF) protein concentrations in pediatric patients who were evaluated for meningitis by traditional criteria and by enterovirus-polymerase chain reaction (EV-PCR). DESIGN AND PATIENTS: A cohort of 906 consecutive pediatric patients to receive CSF analysis at St Louis Children's Hospital, St Louis, Mo, from June 1, 1998, to December 31,1998, was studied for clinical and laboratory data. Age-dependent CSF protein concentrations were then derived from a reference group of 225 patients in whom meningitis and other neurologic diseases were excluded by traditional clinical or laboratory criteria (excluding EV-PCR). Available CSF samples from 132 patients of the reference group were subsequently tested for EV-PCR. RESULTS: In the reference group, the CSF protein concentration was highest and most variable in neonates, with a maximum of approximately 1.0 g/L. Cerebrospinal fluid protein concentration decreased rapidly to a nadir by 6 months and remained low throughout childhood, rarely exceeding 0.3 g/L and, finally, increasing in adolescence toward adult values. Enterovirus- polymerase chain reaction was positive in CSF of 11% of the reference group, with EV-PCR-positive patients having significantly higher CSF protein concentrations than EV-PCR-negative patients aged between 4 months and 14 years. CONCLUSIONS: Reference values for CSF protein exhibit a characteristic age dependence in pediatric patients. Continued standard use of adult reference values in the pediatric population is inappropriate. The unexpected finding of a positive EV-PCR in patients not diagnosed with meningitis by traditional criteria further emphasizes the importance of selecting the most clinically relevant reference group for age and other variables when defining normal laboratory values. Arch Pediatr Adolesc Med. 2000;154:827-831

Adolescent↗

PubMed1997

Age- and education-specific reference values for the Mini-Mental and modified Mini-Mental State Examinations derived from a non-demented elderly population.

MAIN OBJECTIVE: To report age- and education-specific reference values for the Mini-Mental State Examination (MMSE) and Modified Mini-Mental State (3MS) Examination. DESIGN: Cross-sectional study. SETTING: Community and institutional settings in five regions across Canada. PARTICIPANTS: 7754 subjects aged 65 and over randomly chosen to take part in the Canadian Study of Health and Aging. Subjects classified as cognitively impaired or demented following a clinical and neuropsychological examination were excluded. MEASUREMENTS: Total scores on the MMSE and 3MS, and the degree to which they are influenced by the age, sex, education, mother tongue and living environment of the subject. RESULTS: Reference values on the two tests are reported through various descriptive statistics for five age groups and four education levels. These values decrease with age and increase with years of schooling. Test scores are also influenced by the subject's sex and mother tongue, albeit to a lesser extent. These observations led to the development of predictive equations of the performance to be expected from a 'normal' elderly subject, given his/her socio-demographic characteristics. CONCLUSION: The use of the reference values and related predictive equations will allow the clinician to interpret a patient's performance on two widely used cognitive tests, in light of the value expected from a group of 'normal' subjects with the same sociodemographic profile.

Age Factors↗

PubMed2001

Regional reference values for some quantities measured with the ADVIA Centaur analyser. A model of co-operation between the in vitro diagnostic industry and clinical laboratories.

This work is a model of co-operation between the in vitro diagnostic industry and clinical laboratories for the production of reference values. Thirteen clinical laboratories having an ADVIA Centaur analyser and representing the majority of the geographical regions of Spain have shared the search for reference individuals and the production of reference values for thyrotropin, free thyroxine, free triiodothyronine, cobalamine and folate concentrations in serum. All the logistic work has been done in co-operation with the Spanish supplier of the ADVIA Centaur analyser. The reference limits produced in the virtual laboratory are derived from the blend of reference values obtained by each laboratory. The multicentre reference limits were estimated according to the recommendations of the International Federation of Clinical Chemistry and Laboratory Medicine (IFCC).

Adult↗

PubMed1994

Lung function reference values in Singaporean children aged 6-18 years.

BACKGROUND: A study was undertaken to produce reference values of lung function in Chinese children and a means of calculating adjusted standard deviation scores of lung function for Malay and Indian ethnic groups. METHODS: A cross sectional study of lung function (forced expiratory volume in one second and forced vital capacity) measured with a Jaeger spirometer was performed in a representative sample of Singaporean children made up of 1403 Chinese, 335 Malays, and 206 Indians. RESULTS: The relation between natural logarithms of lung function and height was approximately linear until 150 cm in boys and 140 cm in girls. At these heights there were abrupt changes in the gradients of both lines. Separate regression lines were derived for heights above and below these inflection points. Significant differences in lung function were seen in Chinese compared with Malay and Indian children. In particular, values were considerably lower among Indian boys. CONCLUSIONS: The relation between lung function and height in Chinese children is best described by two regression equations over separate height ranges. Information is provided for the calculation of reference values and standard deviation scores, together with the correction factors that need to be applied to derive these values in Malay and Indian children.

Adolescent↗

PubMed1981

[Reference values for a new alpha-amylase determination in serum and urine (author's transl)].

Reference values for a new alpha-amylase estimation using maltoheptaose as substrate were determined in 251 healthy men and women in serum at 25 degrees C and at 30 degrees C and in urine at 25 degrees C. Sex dependency was not demonstrable. The following reference ranges are suggested: 30-100 U/l in serum at 25 degrees C, 40-130 U/l in serum at 30 degrees C, and 500 U/l in urine at 25 degrees C. In addition reference values for the relative percentual amylase-creatinine clearance (25 degrees C) of 0.25-4% and for amylase activity per mg creatinine (urine 25 degrees C) of 0.02-0.25 U/mg creatinine are suggested.

Adolescent↗

PubMed1985

Time domain spirogram indices. Their variability and reference values in nonsmokers.

A cross-sectional population survey of dynamic ventilatory lung function was performed to determine the variability of and reference values for time domain spirogram indices. The reference population comprised 83 men and 143 women who were healthy nonsmokers. The time domain indices were derived from the blow with the largest sum of FVC and FEV1. Prediction equations for FEV1 and mean flow between 25 and 75% FVC were little influenced by methods for selecting the data from the 3 blows recorded. The variability of the first 2 moments of the spirogram increased with age, requiring a log transformation for regression analysis. Prediction equations for conventional and time domain spirometric indices are presented and reference values are proposed based on an estimated percentile derived from the predicted value and the residual standard deviation from regression. Two time domain indices are identified that may prove better suited than conventional indices for identifying abnormalities in the tail of the spirogram.

Adult↗

PubMed2003

Lymphocyte subset enumeration in HIV seronegative and HIV-1 seropositive adults in Dar es Salaam, Tanzania: determination of reference values in males and females and comparison of two flow cytometric methods.

The level of CD4(+) T-lymphocytes represents a useful marker with which to monitor the progression of HIV infection. Sex and geographical differences in the reference values of lymphocyte subsets have been reported. We have compared two flow cytometric methods (MultiSET and SimulSET) for the quantification of lymphocyte subsets using whole blood from 92 HIV seropositive and 241 seronegative adults, and determined the reference values of lymphocyte subsets in HIV seronegative Tanzanian subjects. In seronegative Tanzanian subjects, the percentages of CD3(+) and CD4(+) T-lymphocytes and the CD4(+):CD8(+) T-lymphocyte ratios were lower while the percentage of natural killer cells was higher compared to the levels of the corresponding parameters reported for Europeans. Seronegative Tanzanian females had significantly higher levels of CD3(+) and CD4(+) T-lymphocytes and CD4(+):CD8(+) T-lymphocyte ratios compared to seronegative males. The correlation coefficients of CD3(+), CD4(+) and CD8(+) T lymphocyte counts and percentages obtained by the two flow cytometric methods were high. The median values of the number of CD4(+) T-lymphocytes obtained by the two methods were not significantly different. In conclusion, determination of the reference values of lymphocyte subsets in HIV seronegative Tanzanian adults showed significant sex differences and differences in percentage values compared to those reported in certain other geographical areas. There was acceptable agreement in the levels of CD4(+) T-lymphocyte values obtained by the two flow cytometric methods.

Adult↗

PubMed2003

Spirometric reference values in a large Middle Eastern population.

Ethnic differences in pulmonary function have been frequently reported. The purposes of this study were to derive equations for the prediction of normative spirometry values for a large population of Persians in Isfahan and compare them to reference values from a White Euro-USA population. Spirometry measurements were obtained from 4,341 randomly selected healthy nonsmoker subjects in Isfahan, Iran, utilising American Thoracic Society guidelines and a vigorous quality assurance program. Measured data from 3,213 subjects were analysed using multiple regression techniques to derive prediction equations for spirometric variables; the remaining 1,128 subjects were used as a control group to test the validity of the derived equations. In addition, predicted values were compared with values derived from recently published equations for the USA. Derived prediction equations showed good performance for most spirometric parameters. Compared with USA Whites, adult Persians have minimally lower forced vital capacities, while the values for children are close to USA Whites. In comparison with reference equations based on European or USA populations, local reference values are more biologically and technically suitable for the interpretation of spirometric data from Iranian populations.

Adult↗

PubMed1988

[Reference values for the maximal expiratory flow volume curve for adults. Results of a cooperative study].

Reference values of the maximal expiratory flow-volume curve for the adult GDR's population have been ascertained by a co-operative study of 5 lung function laboratories. We analysed measurements in 1,004 healthy subjects aged 16 to 69 years (728 males and 276 females). Prediction equations for the maximal expiratory flow rates, several time constants of lung mechanics and screening parameters of ventilatory inhomogeneity have been calculated by means of the multiple linear regression analysis. Our reference values are in good accordance with SEPCR summary equations. It is recommended to subtract from or add to the predicted values 1.64 standard deviations and to consider abnormal all values beyond this limit.

Adolescent↗

PubMed2002

Reference values of selenium in plasma in population from Barcelona. Comparison with several pathologies.

Plasma selenium reference values from healthy donors in the metropolitan area of Barcelona are determined. A random sample from 156 healthy adults (control group) is analysed by using electrothermal atomic absorption spectrometry with Zeeman effect background correction. The relationship between several pathologies and Se content is also evaluated. Se content from 64 samples from subjects with chronic renal failure and 54 from subjects suffering from several malignancies are determined and the results are compared to the reference values. Moreover, Se contents are determined and compared in two groups of children, healthy (19 samples) and children of mothers infected with HIV-1 (16 samples). In the control group, Se plasma concentration ranges between 50 and 145 microg x L(-1) (82.2 +/- 17.5 microg x L(-1)). Significantly lower values are found in the two pathologies studied (malignancy and chronic renal failure), compared to the control group. However, no significant differences in Se content are found between the two groups studied regarding malignancy and chronic renal failure. In children of mothers infected with HIV-1, Se status is significantly lower than that of healthy children.

Adolescent↗

PubMed2005

Reference value for C-reactive protein and its distribution pattern in thai adults.

BACKGROUND: To set a reference value for high-sensitivity C-reactive protein (hs-CRP) in a healthy Thai population and study the effect of time, gender and age on that value. METHODS AND RESULTS: Three hundred and sixty-four subjects, aged between 18 and 74 years, comprising 185 men and 279 women, were studied. Another 10 healthy subjects, aged between 18 and 54 years, were recruited for the study of circadian variation in hs-CRP over the days of the week and the months of a year. The reference value for the Thai adults in the present study was 1.8 mg/L, range 0.2-7.9 mg/L. There was no significant difference in the hs-CRP concentration because of region, time, gender or age (p>0.05), nor was the value affected by time. CONCLUSION: The determination of hs-CRP can be performed at any time and the hs-CRP value determined by this study can be used as the reference for Thai adults.

Adolescent↗

PubMed1985

[Microbiological reference values for food products].

This article describes the procedure recommended for setting up the ranges of microbiological reference values for foodstuffs, to be used in the microbiological inspection procedures of the integrated quality guarantee system. Such reference values should be based on 'Good Management Practices' (GMP) programmes. Strategic intervention, through control of the production line, in order to correct the contraventions evident in the GMP programme, is the first necessity in guaranteeing microbiological quality. Also, the hygienic/microbiological supervision of end products remains indispensible, so that the effectiveness of prevention procedures can be verified. In this way, errors which may have previously escaped detection can be found and eliminated. It is emphatically pointed out that only through cooperation between experts of various disciplines involved directly in animal health, working under one 'umbrella' organisation, can the best guarantee of efficacious protection be offered to the consumer.

Food↗

PubMed2000

Nationwide standardisation and evaluation of scintigraphic gastric emptying: reference values and comparisons between subgroups in a multicentre trial.

By means of a standardised procedure, reference values for scintigraphic gastric emptying were established. The influence of gender, age, menstrual cycle, body mass index (BMI) and smoking habits was also evaluated. Eight centres recruited 20 healthy subjects each. The meal consisted of a technetium-99m labelled omelet (1,300 kJ) and of 150 ml unlabelled soft drink. Geometric means of frontal and dorsal acquisitions were utilised in a linear fit model for determination of the linear emptying rate, and by using the intercepts of the regression line with the 90% and 50% levels, the lag phase and half-emptying time, respectively, were defined. All individuals showed an initial lag phase and subsequent linear emptying. Because of a longer lag phase and a slower linear emptying rate, premenopausal women had a slower gastric emptying than postmenopausal women and men of all ages. The gastric emptying rate increased with age in the women, mainly due to a shortened lag phase, while the emptying rate remained almost unchanged with age in the males. There were no significant differences in results between the centres. The menstrual cycle, BMI and smoking habits did not affect emptying. In conclusion, the fact that the results showed a slower gastric emptying rate in younger women compared with older women and men indicates that it is necessary to use separate reference values for fertile females.

Adolescent↗