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PubMed2002

Triplet placentas: reference values for weights.

The occurrence of twins, triplets, and other multiple births increased significantly between 1970 and 2000 in the United States and other industrialized countries. The number of triplet placentas submitted for examination as pathologic specimens has also markedly increased, but no reference values are published for triplet weights. We examined 196 normal triplet placentas. Specimens with associated conditions known to affect the weights of the placentas were excluded. The gestational ages ranged between 20 and 38 weeks. Mean weights for different gestational ages are summarized as follows: 253 g for 20 weeks, 319 g for 22 weeks, 406 g for 24 weeks, 509 g for 26 weeks, 621 g for 28 weeks, 738 g for 30 weeks, 855 g for 32 weeks, 965 g for 34 weeks, 1,065 g for 36 weeks, and 1,147 g for 38 weeks. Weight gain of triplet placentas appears to parallel that of twin placentas. The mean values of placental weights for triplets at each gestational age are less than triple those of singleton weights for the same duration of gestation. The placental weights in multiple gestations do not increase proportionately with the number of fetuses.

Female↗

PubMed1992

Distributions of hemostatic variables in blacks and whites: population reference values from the Atherosclerosis Risk in Communities (ARIC) Study.

The Atherosclerosis Risk in Communities Study measured hemostatic variables in nearly 16,000 men and women, aged 45 to 64 years, from four US communities. This report, based on the first 12,681 participants, presents distributions of fibrinogen concentration, factor VII activity, factor VIII activity, von Willebrand factor antigen, protein C antigen, antithrombin III activity, and activated partial thromboplastin time. Many of the hemostatic variables differed between blacks and whites, and by sex and age. For example, compared to whites, blacks had higher mean values of fibrinogen, factor VIII, von Willebrand factor, and antithrombin III, and lower mean values of protein C. Some seasonal fluctuations in hemostatic variables were noted; most notably, mean values of factor VII were lowest and protein C were highest in subjects examined in the summer compared to those examined during the other seasons. These results provide population-based reference values on blacks and whites for those interested in the relation of hemostasis to disease.

Arteriosclerosis↗

PubMedDate not supplied

[Reference values and tolerance intervals].

Statistical aspects of tolerance intervals estimation are considered and tolerance coefficients for unilateral and central intervals are derived for normally distributed biological variables. The difference between confidence and tolerance interval is explained and application to biological and environmental monitoring, as well as applications to reference values estimation, are exemplified. Tables of unilateral and central coefficients are also produced and reported for different sample dimensions, confidence, and tolerance levels.

Environmental Monitoring↗

PubMed1994

Sensory thresholds in older adults: reproducibility and reference values.

To evaluate the test-retest reproducibility of vibratory perception (VPT) and thermal discrimination (TDT) thresholds on the foot in older adults, we examined 20 50-76-year-old subjects with, and 19 without non-insulin-dependent diabetes mellitus. Adjusted reference values for both thresholds were obtained by assessing the relations with age, body height, and sex among 216 subjects with normal glucose tolerance, of the same age, sampled randomly from a geographically defined general population. The VPT appeared to be more reproducible than the TDT (reliability coefficient 0.89 vs. 0.54). The reproducibility of the VPT was inversely related to age and better for men than for women. Diabetes and glycemic level did not affect the reproducibility of either threshold. Both thresholds were related to age and height. Women had a higher VPT than men. The relations between sex and sensory thresholds at the lower limb, reported in previous studies, were probably confounded by height.

Age Factors↗

PubMedDate not supplied

[Reference values for apolipoproteins and HDL-2/HDL-3 in childhood].

It is known from epidemiological studies, that high apolipoprotein B or low HDL-2 concentrations in serum are correlated with an increased risk for premature cardiovascular diseases. It was the aim of this study to generate reference values for apolipoproteins and HDL-cholesterol fractions to accomplish early diagnosis and therapy. All concentrations are age depending, being low at birth and increasing during the first years of life. This rise is more pronounced in apolipoprotein B than in apolipoprotein AI and HDL-2. Apolipoprotein II and HDL-3 reach later childhood values as early as at the end of the first month of life. The ratio of B and AI, which is a very good indicator for an increased risk for premature cardiovascular diseases, moves also distinctively upward during the first year of life.

Apolipoproteins↗

PubMed1983

Haematology of the racing Thoroughbred in Australia 1: reference values and the effect of excitement.

Eight hundred and sixteen blood samples were collected from horses at Sydney race tracks, 1 to 3 h before racing, and subjected to haematological analysis. Haemograms were also performed on 65 blood samples taken from horses at rest in their stalls. These were used as reference values of prerace and resting haemograms, respectively. The haemograms of 29 of the resting horses were compared with the haemograms of the same 29 horses the following day at the race track. Both samples were considered to be representative of their reference populations. In general, there was a significant increase from the resting to prerace packed cell volume, haemoglobin, red cell count, white cell count and total plasma protein, although the extent of the increases varied between horses and, in a minority, levels were unchanged or decreased. The degree of variability in the prerace samples was not greater than that of the resting samples.

Animals↗

PubMedDate not supplied

[Spirographic reference values. Mathematical models and practical use (author's transl)].

Various models predicting VC and FEV1 from age and height have been compared by both theoretical and practical approaches on several subgroups of a working population examined in 1960 and 1972. The models in which spirographic values are proportional to the cube of the height give a significantly worse fit of the data. All the other models give similar predicted values in practical terms, but cutoff points depend on the distributions of VC and FEV1 given age and height. Results show that these distributions are closer to a normal than to a lognormal distribution. The use of reference values and classical cutoffs is then discussed. Rather than using a single cutoff point, a more quantitative way is proposed to describe the subjects' functional status, for example by situating him in the percentile of the reference population. In screening, cutoff points cannot be choosen without specifying first the decision considered and the population concerned.

Adult↗

PubMed1985

Serum protein reference values in foals during the first year of life: comparison of chemical and electrophoretic methods.

Normal reference values for serum proteins of foals from birth to 1 year of age have been established. Chemical and electrophoretic/refractometric methods for total protein, albumin, total globulin and Albumin/Globulin (A/G ratio) have also been compared. The biuret total protein method and Bromcresol Green (BCG) method on the Technicon SMA 12/60 autoanalyzer were used and compared with total protein determined via refractometry and albumin determined by Cellulose Acetate (CA) electrophoresis/densitometry. Globulin and A/G ratios were calculated from the chemical method data and compared with that obtained electrophoretically. Total protein, albumin, total globulins and A/G ratios all were in agreement at all sample times studied. Data on the subfractionation of serum globulins via CA electrophoresis is also presented. Wide variations in alpha and beta globulin levels were noted among the foal sera early in life. As a result, two distinct populations of foals with respect to both globulin content and A/G ratio were identified. One of these populations (Group A) appeared to have obtained passive immunity more slowly than the other (Group B) animals. Comparison of these data with clinical cases of foals in which failure of passive transfer was a part suggests that the A/G ratio may be useful in assessing adequate colostral antibody levels in the newborn foal.

Journal Article↗

PubMed2001

Reference values for peripheral blood B-lymphocyte subpopulations: a basis for multiparametric immunophenotyping of abnormal lymphocytes.

BACKGROUND AND OBJECTIVES: Immunophenotyping has become a useful tool for the differential diagnosis of chronic B-cell lymphoproliferative disorders. The aim of this work was to determine reference values of normal B-cell subpopulations. MATERIAL AND METHODS: Blood samples from 38 healthy volunteers were analyzed by multidimensional flow cytometry, using a panel of directly conjugated antibodies. Results were expressed as percent of positive B cells and as median fluorescence intensity, an indirect assessment of the expression level. RESULTS: CD20, CD22, CD24, CD40, CD79a, CD79b, FMC7, CD11a, CD18, CD44 were positive in the whole B cell population, whereas CD10, CD86, CD103, CD154 and FasL were almost absent from the B-lymphocyte population. 75% were IgD positive. The kappa/lambda ratio was 1.5. CD5, CD23, CD25, CD38, CD43, CD54, CD62L, CD80 and CD95 were positive in different B-cell subpopulations. The utility of all these markers in the differential diagnosis of chronic B-cell lymphoproliferative disorders is discussed. CONCLUSION: In order to interpret a pathological immunophenotype, it is necessary to refer to quantitative and qualitative values of normal B-cell subpopulations.

Adult↗

PubMedDate not supplied

[Determination of some usual and frequent values in clinical biochemistry in a Polynesian population sample. Comparison with French reference values].

The normal values for glucose, urea, uric acid and creatinine in serum have been determined in a selected Polynesian population. The results are similar for obese or non-obese subjects as well as for the people living in Papeete. A comparison between these data and the French standard values reveals significant differences in regard to glucose, urea and uric acid.

Adult↗

PubMed1979

EEG spectra in children aged 8, 9 and 10 years. Reference values.

In a group of normal children aged 8, 9 and 10 years power density spectra of a 100-second EEG period were made over four different brain regions. All children had to undergo medical and psychological examinations prior to this EEG and the criteria for normality were based on these examinations. Reference values of the power density distribution for children between 8 and 10.5 years are given.

Age Factors↗

PubMed1994

Creatine kinase in dog plasma: preanalytical factors of variation, reference values and diagnostic significance.

In the dog, plasma creatine kinase (CK) activity was stable up to one week at +4 degrees C and one month at -20 degrees C. Activity was higher in serum than in plasma due to interference by CK from the platelets. The reference values were determined in 232 dogs using the IFCC recommended method. There was a significant decrease in activity with age but no effect of sex. In adults, plasma CK exhibited a log-normal distribution ranging from 20 to 104 U per litre. In 510 dogs with various diseases, the overall sensitivity and specificity of CK determination were 40 per cent and 98 per cent, respectively. The numerous false negatives could result from the relatively short half-life of the enzyme, while the false positives could be due to secondary muscle damage.

Animals↗

PubMed1992

Trace element reference values in tissues from inhabitants of the European Community. III. The control of preanalytical factors in the biomonitoring of trace elements in biological fluids.

In the context of a programme concerning the determination of trace elements in body fluids and tissues to establish trace element reference values, research has been undertaken on the control of preanalytical factors in order to develop sufficiently accurate and precise guidelines to be applied in routine work by using techniques such as graphite furnace atomic absorption spectroscopy (GFAAS). Aspects investigated are related to the risk of contamination during blood collection and the use of anticoagulants; the risk of losses during storage and freeze-drying as well as the possible risk of contamination arising from trace elements in airborne particulates of the laboratory environment. For the analysis of Al, Ba, Cd, Co, Cr, Mn, Mo, Ni, Sb, W, V and Zn in blood, Teflon cannula is the method of choice. The anticoagulants do not introduce disturbing contaminations of Rb, Se, Zn, while contaminations were observed for Co, Cr, Mn. Radiotracers in 'metabolized form' (radiolabelled rat or rabbit tissues from animals administered with radioisotopes) show that samples stored for 1 month at -20 degrees C have no significant trace metal losses. Strict ambient air quality standard has to be respected (continuous monitoring) due to the possibility of element contaminations inside the laboratory. The use of matrix modifiers could represent a toxicological risk to the operators. Critical factors should be considered ('metal sheets') for each element in each matrix. For instance 27 factors for Cr in serum have been suggested.

Air Pollutants, Occupational↗

PubMed1990

Tumor markers in human prostatic carcinoma. An optimation of reference values.

Serum concentrations of prostatic acid phosphatase, prostate-specific antigen, neopterin, osteocalcin, tissue polypeptide antigen, and CA-50 were measured before onset of treatment in 86 patients suffering from prostatic carcinoma. In an attempt to identify patients with a poor prognosis, the data were related to patient survival after 3 years. When the standard reference values, which are based on studies on healthy subjects, were used in the study on the deceased, the diagnostic sensitivity was acceptable, whereas the diagnostic specificity was low. A better relation to prognosis was obtained if higher discrimination values were employed. The increased specificity could be obtained with little loss of sensitivity. It is suggested that the discrimination value should be chosen after careful consideration of the expected performance of the test in differentiating between defined groups of patients. To indicate short-term prognosis in prostatic cancer, a higher than normally recommended discrimination value for the marker should be selected.

Aged↗

PubMed1992

Cardiac two-dimensional imaging and reference values for blood flow velocities in the ovine fetus.

Since the ovine model is the most commonly used for foetal haemodynamic investigation it was felt important 1) to investigate the technical difficulties involved with ultrasound fetal cardiac imaging in this species and 2) to establish normal reference values for ovine cardiac and umbilical blood flow velocity measurements. Both two-dimensional and pulsed Doppler techniques were used for this assessment in 25 unsedated ewes. All morphological features described in human features to identify the ventricular cavities could be found in the ovine fetus with the two-dimensional echocardiogram. Specific differences included a flatten thorax as visualized from the lateral position, the mesocardial position of the heart, and a large left azygos vein behind the left atrium draining blood into a dilated coronary sinus. The mean peak velocities (cm/sec) of the early diastolic wave (E) and the atrial wave (A), along with their calculated ratio, were not statistically different between the two atrio-ventricular valves (E: 30.6 +/- 6.6, 31.2 +/- 6.1; A: 43.0 +/- 8.3, 41.6 +/- 8.0; E/A: .72, .76 for mitral and tricuspid valves respectively). A significant difference was observed between the acceleration times of the blood ejected into the aorta and the pulmonary artery, with the time interval being shorter in the pulmonary artery (Aorta: 0.052 +/- 0.011; Pulmonary artery: 0.037 +/- 0.009 s). A mean pulsatility index of the umbilical artery of 0.89 was recorded. The data recorded in this study should serve as a reference base for further non-invasive studies of the ovine foetal circulatory system using the ultrasound technique.

Animals↗

PubMed2003

Amniotic fluid index in normal pregnancy: an assessment of gestation specific reference values among Indian women.

AIM: To obtain a gestational reference range for the amniotic fluid index (AFI) among Indian women. METHODS: An analysis of AFI estimations was undertaken in 517 Indian women with normal pregnancy between 16 and 42 weeks of gestation. It was a prospective, cross-sectional study conducted in a university teaching hospital. Women with fetal anomalies, pregnancy-induced hypertension, diabetes mellitus, and other maternal complications were excluded from the study. The median, the 5th and the 95th percentile values were calculated for each gestational week and these values were compared with other studies. RESULTS: The median reached its peak at the 27th week of gestation. We observed approximately 6 cm as the lower limit of normal (5th percentile) and approximately 18 cm (95th percentile) as upper limit of normal AFI at term for our population, whereas in the Caucasian population, the values were approximately 7 cm and approximately 20 cm, respectively. All gestation specific AFI values were lower in the studied population of Indian women compared with other studies on Caucasian population (P < 0.01 for 5th percentile & P < 3.26 x 10(-7) for 95th percentile), but slightly higher than the Chinese population. CONCLUSION: Amniotic fluid index values differ in different populations. We standardized the reference values for normal AFI in Indian women. We found that they are lower in the population studied compared with reported values in the Caucasian population, but slightly higher than the Chinese population.

Amniotic Fluid↗

PubMed1989

Enzyme immunoassay of lactoferrin in newborn term infants: reference values and influence of diet.

Plasma lactoferrin is an acute phase protein which may have a variety of roles in the anti-infective process. As the diagnosis of infection in infants is particularly difficult, measurement of this protein could make a useful contribution, however previous reference values for infants were unsatisfactory. A solid phase enzyme immunoassay for plasma lactoferrin which required only a small specimen of blood was established. It was linear up to 800 micrograms/L, with a recovery of between 96 and 99%, and had a between batch precision of between 10 and 15%. Using this method we have determined the level of circulating lactoferrin in term infants during the first three weeks of life to be (mean +/- SD) 385 +/- 113 micrograms/L which is significantly (P less than 0.005) higher than that found in adults (venous plasma 122 +/- 40 micrograms/L; capillary plasma 107 +/- 73 micrograms/L). Plasma lactoferrin levels were still significantly higher than those in adults at weeks 7 and 11 (267 +/- 176 micrograms/L and 269 +/- 163 micrograms/L respectively) but not at week 15 (176 +/- 165 micrograms/L). There were no differences between infants fed breastmilk and those fed on infant formulas. These findings are discussed in terms of the possible origin and role of lactoferrin in the newborn.

Adult↗

PubMedDate not supplied

Reference values for stationary and 24-hour ambulatory esophageal manometry and pH data in Hispanic population.

BACKGROUND: It has not yet been determined whether values obtained with stationary esophageal motility test are similar to those obtained with the 24-h procedure. Furthermore, there are no normal values established for esophageal pH and motility parameters in a Hispanic population. METHODS: Reflux symptoms, endoscopy, Helicobacter pylori, stationary esophageal manometry, and combined 24-h pH-manometry were evaluated in 12 healthy volunteers. Three subjects also underwent 24-h esophageal bilirubin monitoring. RESULTS: Mean lower esophageal sphincter pressure measured stationary was lower (p<0.05) compared with 24-h ambulatory procedure. Mean duration of contraction waves was greater with stationary method (p<0.05). Esophageal contraction mean amplitude was not different between both procedures. Total percent of time with pH<4 was 0.16+/-0.21. Total 24-h acid reflux episodes were 5.5+/-6.6, with no episodes >5 min. No high bilirubin reflux episodes were recorded. CONCLUSIONS: These results suggested that physiologic motility parameters differed depending on the method employed for its evaluation. Values obtained with stationary and 24-h ambulatory esophageal manometry are identical when evaluating amplitude of contractions but differ in duration of contractions and lower esophageal sphincter pressure. In addition, these results provide for the first time reference values for stationary and 24-h ambulatory esophageal manometry and pH data in a Hispanic population.

Adult↗