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PubMed1994

Studies on red cell glucose-6-phosphate dehydrogenase: evaluation of reference values.

The analytical, intra-individual, inter-individual variation and reference values were determined for red cell glucose-6-phosphate dehydrogenase (G6PD). Different procedures for the conditions for storage of red blood cells and the preparation of haemolysates were investigated. A total of 2170 samples of blood were taken from apparently healthy persons-1212 males and 958 females--from randomly selected villages and city centres in the southern part of Turkey. Analytical variation, intra-individual variation and inter-individual variation were 8.67%, 32.8% and 31.8%, respectively. The mean (SD) for G6PD was 8.6 (3.3) IU/gHb. The index of individuality, 1.03, showed that the reference intervals could be used for diagnostic purposes. Whole blood or a red cell pellet could be stored in physiological saline for one week at 4 degrees C or -20 degrees with little loss of activity. Two of three different procedures for the preparation of haemolysate gave data that showed no statistical difference and were equally satisfactory.

Blood Specimen Collection↗
PubMed2006

Reference values for the timed up and go test: a descriptive meta-analysis.

BACKGROUND AND PURPOSE: The Timed Up and Go (TUG) test is widely employed in the examination of elders, but definitive normative reference values are lacking. This meta-analysis provided such values by consolidating data from multiple studies. METHODS: Studies reporting TUG times for apparently healthy elders were identified through the on-line search of bibliographic databases. Study specifics and data were consolidated and examined for homogeneity. RESULTS: Twenty-one studies were included in the meta-analysis. The mean (95% confidence interval) TUG time for individuals at least 60 years of age was 9.4 (8.9-9.9) seconds. Although the data contributing to this mean were homogeneous, data for individuals who could be categorized by age were more homogeneous. The mean (95% confidence intervals) for 3 age groups were: 8.1 (7.1-9.0) seconds for 60 to 69 year olds, 9.2 (8.2-10.2) seconds for 70 to 79 years, and 11.3 (10.0-12.7) seconds for 80 to 99 years. CONCLUSIONS: The reference values presented, though obtained from studies with clear differences, provide a standard to which patient performance can be compared. Patients whose performance exceeds the upper limit of reported confidence intervals can be considered to have worse than average performance.

Aged↗
PubMed1994

[Hematological reference values for foals in the first two months of life].

Hematologic reference values were established in 18 healthy foals in the first two months of life. Blood samples were collected prior to colostrum consumption and at 30 hours, 1 week, 3, 5, 7 and 9 weeks of age. PCV, Hb and RBC decreased during the first week and RBC, but not PCV and Hb, increased toward the end of the second month. With the exception of the sample at 1 week, the foals had mean RBC values significantly higher than those of controls. Mean MCV and MCH did not change during the first week, but decreased slightly thereafter; all means were smaller than in controls. The numbers of neutrophils increased mainly during the first week, and the numbers of lymphocytes increased gradually during the first two months. The mean N:L-ratio was highest at 1 week and lowest at 5 weeks.

Animals↗
PubMed1987

Normal haematological reference values in the adult black population of the Witwatersrand.

Normal haematological reference values for healthy adult blacks residing on the Witwatersrand are given. The haemoglobin concentration was 13.95 +/- 0.8 g/dl for women and 15.82 +/- 1.05 g/dl for men. Leucocyte counts were lower than those found in whites, being 5.60 +/- 1.51 X 10(9)/l for both sexes. Platelet counts were 280 +/- 59.4 X 10(9)/l for men and 317 +/- 64.0 X 10(9)/l for women. The differential counts and other parameters are given in the text.

Adult↗
PubMed2006

Reference values for exhaled nitric oxide (reveno) study.

BACKGROUND: Despite the widespread use of fractional exhaled nitric oxide (FENO) as a biomarker of airways inflammation, there are no published papers describing normal FENO values in a large group of healthy adults. OBJECTIVE: The aim of this study was to establish adult FENO reference values according to the international guidelines. METHODS: FENO was measured in 204 healthy, non-smoking adults with normal spirometry values using the on-line single-breath technique, and the results were analysed chemiluminescently. RESULTS: The main result of the study was the significant difference in FENO values between men and women, thus indicating that gender-based reference FENO values are necessary. The FENO levels obtained at expiratory flows of 50 ml/s ranged from 2.6 to 28.8 ppb in men, and from 1.6 to 21.5 ppb in women. CONCLUSION: We propose reference FENO values for healthy adult men and women that could be used for clinical and research purposes.

Adult↗
PubMed1998

Reference values for self-recorded blood pressure: a meta-analysis of summary data.

BACKGROUND: The widespread clinical use of self-recorded blood pressure measurement is limited by the lack of generally accepted reference values. The purpose of this study was therefore to perform a meta-analysis of summary data in an attempt to determine an operational threshold for self-recorded blood pressures. STUDIES AND METHODS: Seventeen studies, including a total of 5422 subjects, were reviewed. Eight of these 17 studies included both normotensive and untreated hypertensive subjects, while the other 9 reports included normotensive subjects only. Within each study an operational cutoff point between normotension and hypertension was derived by means of the mean+2 SDs and the 95th percentiles of the self-recorded blood pressure in normotensive subjects. These 2 methods were contrasted with 2 other techniques that have been applied in the literature to calculate (1) the self-recorded pressures equivalent to a conventional pressure of 140 mm Hg systolic and 90 mm Hg diastolic by means of regression analysis and (2) the self-recorded blood pressures at the percentiles corresponding to a conventional pressure of 140/90 mm Hg. The latter 2 methods were applied in untreated subjects not selected on the basis of their blood pressure. RESULTS: With weighting for the number of subjects included in the various studies, the self-recorded blood pressure averaged 115/71 mm Hg in normotensive persons and 119/74 mm Hg in untreated subjects not selected on the basis of their blood pressure. The reference values for self-recorded blood pressures determined by the mean+2 SDs (137/89 mm Hg) or the 95th percentile (135/86 mm Hg) of the distribution in normotensive subjects were concordant within 2/3 mm Hg, whereas the cutoff points derived with the regression and percentile methods were considerably lower, ie, 125/79 and 129/84 mm Hg, respectively. CONCLUSIONS: Until the relationship between self-recorded pressure and the incidence of cardiovascular morbidity and mortality is further clarified by prospective studies, a mean self-recorded blood pressure above 135 mm Hg systolic or 85 mm Hg diastolic may be considered hypertensive.

Blood Pressure Determination↗
PubMed1983

Lipid Research Clinics Program reference values for hyperlipidemia and hypolipidemia.

Plasma cholesterol and triglyceride distributions have been established for 60,502 participants in a survey of ten separate, well-defined North American populations. Lipoprotein cholesterol levels were measured in a 7,055-person random sample of the white participants. From these data, new age- and sex-specific reference values have been selected for the diagnosis of hyperlipidemia and hypolipidemia. The use of these new reference values for population screening would result in the conditions of more young subjects being diagnosed as hypercholesterolemic and a very significant decrease in the proportion of the adult population being diagnosed as having hypertriglyceridemia.

Adolescent↗
PubMed1987

Percentile estimates of reference values for total protein and albumin in sera of premature infants (less than 37 weeks of gestation).

We measured the concentrations of total protein and albumin in sera of 281 well-fed premature infants, gestational ages 22-36 weeks, and calculated reference values from the 10th to 90th percentiles. The mean serum albumin concentration (27.6 +/- 4.4 g/L, mean +/- SD) and total protein concentration (49.2 +/- 6.7 g/L) at a postnatal age of 14.5 days were lower than reference values for full-term infants. We detected a significant positive correlation between albumin concentration and gestational age (r = 0.34, p less than 0.01) and total protein concentration and gestational age (r = 0.43, p less than 0.01). Even though albumin values were low, generalized edema was not present. We conclude that values for total protein and albumin in the preterm infant are lower than in the full-term infant but are an expected physiological response to premature birth.

Blood Proteins↗
PubMed1997

[Reference values for biological parameters in occupational and environmental medicine].

Biological parameters are extensively used in occupational and environmental medicine. They are traditionally evaluated by comparison with normal range. Since 1970's, with the growing skepticism about normal range and researches' progress, the replacing notion of reference values and related theory had gradually come into being with the one which is the most representative, published by International Federation of Clinical Chemistry and International Committee for Standardization in Haematology. This paper introduces those results with emphatic discussion on data processing and statistical procedures. The process of establishing reference limits is illustrated by an example and issues on reference and decision limits, reference band, multivariate reference values are also briefly addressed.

Environmental Medicine↗
PubMed1999

Serum proteins by capillary zone electrophoresis: approaches to the definition of reference values.

The Paragon CZE 2000 (Beckman Analytical, Milan, Italy) is an automatic dedicated capillary zone electrophoresis (CZE) system, producing a five-zone serum protein pattern with quantitative estimation of the zones. With the view of substituting this instrument for two previously used serum protein electrophoresis techniques, we planned to produce reference values for the "new" systems leading to compatible interpretation of the results. High resolution cellulose acetate electrophoresis with visual inspection and descriptive reporting (HR-CAE) and five-zone cellulose acetate electrophoresis with densitometry (CAE-D) were the previously used techniques. Serum samples (n = 167) giving "normal pattern" with HR-CAE were assayed with the CZE system, and the results were statistically assessed to yield 0.95 reference intervals. One thousand normal and pathological serum samples were then assayed with the CAE-D and the CZE techniques, and the regression equations of the CAE-D values over the CZE values for the five zones were used to transform the CAE-D reference limits into the CZE reference limits. The two sets of reference values thereby produced were in good agreement with each other and also with reference values previously reported for the CZE system. Thus, reference values for the CZE techniques permit interpretation of results coherent with the previously used techniques and reporting modes.

Blood Proteins↗
PubMed2006

Reference values for respiratory system impedance by using impulse oscillometry in children aged 2-11 years.

The forced oscillation technique makes it possible to evaluate the mechanical properties of the respiratory system with a minimum of cooperation. The method is therefore especially useful in children. Impulse oscillometry (IOS) is a commercially available version of this technique. There is, as yet, limited information on reference values for IOS in children. The aim of this study was to extend the reference values for IOS variables and to study their correlation with height, weight and age in healthy children. A sample (n = 360) of children (age 2.1-11.1 years) was measured by using impulse oscillometry (IOS; Jaeger, Würzburg, Germany). The sample was based on children attending kindergarten in Finland and children attending primary school in Sweden. Measurements of respiratory resistance (Rrs) and reactance (Xrs) at 5, 10, 15 and 20 Hz, total respiratory impedance (Zrs) and the resonance frequency (Fr) were made. All variables were related to body height. Most of them were also weakly related to weight. Reference equations for children (height 90-160 cm) are presented.

Age Factors↗
PubMed1988

Bone mineral content of mandibles: normal reference values--rate of age-related bone loss.

The purpose was to obtain the normal sex- and age-related reference values for the bone mineral content (BMC) in the bones of the mandible and the forearms, as estimated by dual-photon absorptiometry; to examine the effect of tooth loss on the mandibular BMC, i.e., BMC in the basal part of the mandible; and to analyze the rate of the sex- and age-related BMC loss in the mandible in normal old edentulous individuals greater than or equal to 70 years of age and its relationship to the corresponding BMC loss in the forearm bones. The following groups were measured: young dentate adults (n = 100; women (W): men (M) = 1:1), young, long-term edentulous W (n =15), and old edentulous individuals (n = 24 W, 10 M). In the old group the BMC measurements were repeated after 2- or 3-year period (n = 18 W, 10 M). The analyses indicate that the mandibular BMC reference values differ by sex and age; but correction for the state of dentition seems of minimal benefit. The average BMC loss (%) in the bones of the mandible and the forearms seems to be higher in old W (1.5 and 1.4% per year) than in old M (0.9 and 0.7% per year), but of the same magnitude in each sex. The relationship between the BMC loss (%) in the two sites was significant (P less than 0.01) but rather weak. Thus, it seems important to follow the sex- and age-related BMC loss in the mandible separately.

Adult↗
PubMed2005

Reference values for the weight of freshly delivered term placentas and for placental weight-birth weight ratios.

BACKGROUND: There is evidence for a correlation between placental weight and future chronic disease, notably hypertension and diabetes. However, there are no reference scales for placentas that are readily weighed in the delivery room. METHODS: This cross-sectional study generated reference values for the weight of freshly delivered untrimmed placentas, and placental weight-birth weight (pw/bw) ratios from a database of 11,141 uncomplicated singleton term pregnancies (37-42 weeks). The data analysis followed stringent validated and state of the art methodological recommendations. A regression model was fitted to estimate the mean and standard deviation for placental weight and pw/bw ratios at each week of gestational age. RESULTS: Reference scales, percentile tables and regression equations are presented for placental weights according to the mode of delivery and for pw/bw ratios. Mean placental weight from vaginal deliveries was 76 g lighter than from Caesarean sections (545+/-107 g versus 621+/-139 g, respectively, P<0.05). Mean placental weight increased by 60 g from 37 to 42 weeks irrespective of the mode of delivery. The pw/bw ratio decreased from 17.6 to 15.6 between 37 and 42 weeks. CONCLUSION: For the first time, reference values for freshly delivered term placental weights depending on the mode of delivery were generated. In the light of growing evidence for a correlation of placental weight with chronic diseases in later life, these values provide the possibility to judge placentas at site for abnormalities in weight and to estimate the potential risks for chronic diseases in later life.

Birth Weight↗
PubMed1995

Alveolar lavage fluid (ALF) of normal volunteer subjects: cytologic, immunocytochemical, and biochemical reference values.

OBJECTIVE: Pooled bronchoalveolar lavage fluid (BALF), the return of lavage, contains both bronchial and alveolar material which differ from each other. Artifacts may be created by filtering, centrifuging and washing cells before cytopreparation. This study presents reference values of healthy volunteers for the alveolar sample, ALF, cytopreparation being performed without filtration or centrifugation. METHODS: Eighteen healthy, non-smoking volunteers underwent a standard bronchoalveolar lavage using 10 aliquots of 20 ml of saline. Excluding the return of the first and second aliquots, the rest were pooled and examined cytologically, immunocytochemically and biochemically. The mean, standard deviation, and 95% confidence limits were calculated for the following variables: amount of return, estimated content of epithelial lining fluid (ELF), total and differential cell counts on filter and cytocentrifuge (CCF) preparations, computed cell counts per unit volume of ALF, distribution of lymphocyte subgroups CD3+CD2, CD4, CD8, CD19, CD25 and CD57, and the ratio of CD4 to CD8, the amounts of lymphocytes in the same subgroups per volume of ALF, and the concentrations of total protein, albumin, immunoglobulins A, G and M, hyaluronic acid, eosinophilic cationic protein (ECP), procollagen III aminoterminal propeptide (PCP) and beta 2-microglobulin in ALF and in ELF, as well as the ratios of the concentrations of the solutes in ALF to the same in serum. RESULTS: The 95% confidence limits of means for the most important variables were as follows: estimated ELF content 0.42-0.74%; total cells in ALF 76.6-143.0 x 10(6) l-1; distribution of inflammatory cells on filter and CCF slides: macrophages 74.9-83.6 and 81.4-90.1%, lymphocytes 13.1-22.5 and 8.1-16.4%, and neutrophils 1.0-4.1 and 0.7-2.7%, respectively; distribution of lymphocyte subsets: CD3+CD2 85.6-90.6%, CD4 44.3-53.1%, CD8 26.9-35.8%; concentration of solutes in ALF: total protein 44.8-61.3 mg l-1, albumin 15.4-22.2 mg l-1, IgA 1.8-3.4 mg l-1, IgG 3.1-6.1 mg l-1, IgM 0.05-0.26 mg l-1, hyaluronic acid 8.8-11.1 micrograms l-1, ECP 0.19-0.77 micrograms l-1, PCP 0.005-0.58 micrograms l-1, beta 2-microglobulin 62.2-81.5 micrograms l-1. CONCLUSIONS: Our results show that excluding the bronchial sample from ALF of volunteer subjects and omitting filtering and washing before cytopreparation produces cytologic, immunocytochemical and biochemical reference values with reasonable 95% confidence limits to be used in clinical settings.

Adult↗
PubMed1999

[Reference values of hemosiderin-laden alveolar macrophages in bronchoalveolar lavage in children].

Pulmonary haemosiderosis is a rare disease of unknown etiology, mainly affecting children and adolescents. Pulmonary haemosiderosis may occur in association with several respiratory or other disease (Lupus erythematosus, Goodpastures syndrome). Delay in diagnosing can lead to fatal complications. BAL appears to be the method of choice to detect haemosiderin-laden macrophages. No reference values are available for children to date. 64 bronchoalveolar lavages were performed to establish reference values of haemosiderin-laden macrophages in children. Less haemosiderin was found in children compared to adults, and hence a new haemosiderin score was established for paediatric patients. Compared to healthy children, no elevated haemosiderine levels were found in children with chronic pulmonary disease such as bronchiectasis or chronic aspiration caused by gastro-oesophageal reflux. Therefore even a mildly increased amount of haemosiderin-laden macrophages in children requires medical attention.

Adolescent↗
PubMed2005

[Biochemical detection of Conn's adenoma: definition of criteria and reference values].

Primary hyperaldosteronism is a diagnosis which should be considered in refractory hypertension even in the absence of any hypokalaemia. Its detection relies above all on the levels of renin and aldosterone. The aldosterone/renin ratio has been proposed as the most sensitive criterium. The reference values used for the diagnosis of primary hyperaldosteronism are very variable in the literature, depending not only on the method used but also on the criteria used for their determination. In this study we evaluated the defined reference values prospectively by studying a population of patients with a Conn's adenoma treated surgically. The study included an initial retrospective period which allowed identification of 29 cases of Conn's adenoma treated surgically, and a 9 month prospective period during which 212 reports were collected. During this prospective period a further 9 cases of Conn's adenoma were detected, which were successfully treated with surgery. Analysis to discriminate the 38 Conn's adenomata from the rest showed that 3 parameters contributed significantly and independently to the diagnosis: supine plasma renin activity (ARPc), supine aldosteronaemia and the erect aldosterone/renin ratio, allowing correct classification in 88% of the cases. The reference ranges of these 3 parameters were calculated in order to give a sensitivity of 100% and the best possible specificity, therefore allowing a combined criterium involving all 3 parameters to be defined: ARPc < 0.45 ng/ml/h, supine aldosteronaemia >417 pmol/l, and erect aldosterone/renin >1180.

Adenoma↗
PubMed1998

Reference values of body composition obtained by dual energy X-ray absorptiometry in preterm and term neonates.

BACKGROUND: As previously reported, dual-energy x-ray absorptiometry provides reliable and accurate values for bone mineralization in piglets and infants, but overestimates fat content in small infants. The purpose of the current study was to determine an appropriate equation of correction for fat mass measurement and to establish reference values of body composition of preterm and term neonates. METHODS: Fat mass and chemical whole-body fat content were evaluated by dual-energy x-ray absorptiometry in eight piglets with a body weight between 1408 and 5151 g. The results were combined with previous data obtained in 13 piglets, and two correction equations were determined according to fat mass content. Close to birth, 106 healthy appropriate-for-gestational-age preterm and term infants were scanned by dual-energy x-ray absorptiometry to determine bone mineral content, bone area, and fat mass. Fat mass content determined by dual-energy x-ray absorptiometry was corrected using the equations obtained in piglets after which lean body mass was recalculated. RESULTS: Multivariate analysis showed that dual-energy x-ray absorptiometry body weight was the best predictor of bone mineral content (r2 = 0.94), bone area (r2 = 0.95), lean body mass (r2 = 0.98), and fat mass (r2 = 0.84). Gender was an additional significant independent variable for fat mass and lean body mass. Body weight related curves of percentiles for bone mineral content, bone area, fat mass, and lean body mass, were constructed. In vivo dual-energy x-ray absorptiometry values of fat mass and calcium content estimated from bone mineral content were in accordance with previously reported whole-body carcass reference values in preterm and term neonates. CONCLUSION: Normative data of dual-energy x-ray absorptiometry body composition for healthy preterm and term infants are provided and can therefore be used in research and in clinical practice.

Absorptiometry, Photon↗