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PubMed1990

Cerebrospinal fluid lipoperoxides quantified by liquid chromatography, and determination of reference values.

Cerebrospinal fluid lipoperoxides, measured as the malondialdehyde-thiobarbituric acid (MDA-TBA) adduct, were quantified by adapting the plasma liquid-chromatographic method of Wong et al. (Clin Chem 1987;33:214-20) to cerebrospinal fluid. Reference values for spinal fluid specimens from 91 adults, ages 17 to 95 y, and 37 children, ages 8 d to 8 y, were determined. Their concentrations were not significantly different (P = 0.222), adults having a mean (and SD) of 0.11 (0.06) mumol and children 0.10 (0.04) mumol of MDA per liter. Their ranges were 0.02-0.26 and 0.04-0.21 mumol of MDA per liter, respectively. We found concentrations in cerebrospinal fluid to be increased in several central nervous system disorders, including seizures, cerebral infarction, alcoholic encephalopathy, and, perhaps, prematurity. The presence of other thiobarbituric acid-reactive substances in cerebrospinal fluid stresses the importance of using highly specific techniques when lipoperoxides are measured in body fluids.

Adolescent↗
PubMed1981

Reference values for equine peritoneal fluid.

Twenty horses, aged one to 17 years (mean age 6 years), presented for elective destruction and subsequently found at autopsy to have no significant peritoneal alterations, were used to determine a variety of reference values for peritoneal fluid. Samples were collected ante mortem or within 1 h post mortem. Each cavity contained 100 to 300 ml of usually clear, pale yellow fluid which in a clinical refractometer showed a mean specific gravity 1.010 (range 1.0081-1.0116) and mean (+/- standard deviation) total protein 7.7 +/- 3.6 g/litre. The mean total nucleated cell count (+/- sd) was 4.33 +/- 2.5 x 10(9)/litre (range 1.5-10.1 x 10(9)/litre) and, proportionally, polymorphonuclear leucocytes averaged 45.2 per cent, mononuclear phagocytes 47 per cent, lymphocytes 7.8 per cent, eosinophils 0.7 per cent and basophils and mast cells zero. Eosinophils were not usually seen but 6 samples had 1 to 5 per cent. The peritoneal fluid chemical profile (mean +/- sd) was: Aspartate aminotransferase (AST) 118.9 +/- 46.9 iu/litre; alkaline phosphatase (AP) 56.0 +/- 52.7 iu/litre; lactate dehydrogenase (LDH) 143.0 +/- 106.1 iu/litre; total bilirubin (TB) 8.0 +/- 6.2 mumol/litre; total protein (TP) (biuret method) 14.2 +/- 6.8 g/litre; urea nitrogen (BUN) 6.1 +/- 1.1 mmol/litre; glucose 7.7 +/- 1.8 mmol/litre; inorganic phosphate (IP) 1.4 +/- 0.5 mmol/litre; calcium 2.0 +/- 0.2 mmol/litre. TP, BUN, glucose and IP were closely correlated with levels in paired serum samples.

Animals↗
PubMed1984

Reference values for urinary calcium excretion and screening for hypercalciuria in children and adolescents.

Hypercalciuria is of continuing interest as one of the risk factors for stone disease in children, but the definition, incidence and pathogenesis are controversial. Therefore reference values for the urinary calcium/creatinine (Ca/Cr) ratios were established in 564 healthy children aged 6-17.9 years during the fasting state (09.00 h) and in 236 of them also in the post-absorptive state about 2 h after lunch (14.00-16.00 h). The Ca/Cr ratios in both urine specimens were independent of age and sex, rendering it possible to determine a common normal range and to calculate centiles for Ca excretion in a large sample of healthy children and adolescents. To provide information about the incidence of hypercalciuria the Ca/Cr ratios of 1013 other apparently healthy children aged 6-17.9 years were measured during the post-absorptive state on two consecutive days. In 39 (3.8%) of them, 21 girls, and 18 boys, the Ca excretion was elevated in both urine specimens. Thirty-six of these children, all presenting without renal complaints, underwent further investigations to elucidate the possible mechanisms of the hypercalciuria. On the basis of the Ca/Cr concentration during the fasting state and the calciuric response to a standardised oral Ca tolerance test the children were subclassified into three groups: (1) Absorptive hypercalciuria (AH, n = 12): Increased calciuric response to the Ca load, but normal fasting Ca/Cr; (2) Renal hypercalciuria (RH, n = 8): Increased Ca/Cr after Ca load and during the fasting state; (3) Normal Ca excretion during the fasting state and after the Ca tolerance test, but increased sodium excretion (dietary hypercalciuria, DH, n = 16).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed2006

Reference values for the 6-min walk test in healthy subjects 20-50 years old.

In 102 healthy Caucasians, 20-50 years old, we investigated the effect of anthropometrics on the 6-min walk test (6MWT), in order to provide reference values for walk distance (6MWD), oxygen saturation (SpO2), pulse rate (PR), respiratory rate (RR), breathlessness perception (VAS) and for the walking distance and body weight product (DW). The mean 6MWD and DW values were 593 +/- 57 and 638+/-44 m (P < 0.01) and 35,030 +/- 5306 and 48,882 +/- 6555 kg m (P < 0.01), respectively for women and for men. While walking, SpO2 remained unaltered and subjects reached 67 +/- 10% of their maximal predicted heart rate and a RR mean value of 19 +/- 4 bpm. VAS ratings were significantly higher in females as compared to males (24 +/- 15 vs. 18 +/- 5 mm, P < 0.05), however, when corrected for PR change while walking, they were not different. The equation by stepwise multiple regression analysis included height, age and gender for the 6MWD and accounted for 42% of the total variance. This study confirms the relevant effect of anthropometrics on walking capacity and suggests that when rating dyspnea, the change in heart rate during walking should be considered.

Adult↗
PubMed1984

[Reference values for the inhomogeneity parameter V2/V1].

In 1,169 healthy subjects (821 males and 348 females) aged 15 to 70 years was determined parameter V2/V1 from the flow-volume loop for the estimation of unequal ventilation by means of the electronic spirometer Pneumotest. Reference values and prediction equations for parameter V2/V1 are reported.

Adolescent↗
PubMed1997

Doppler echocardiographic reference values for healthy rhesus monkeys under ketamine hydrochloride sedation.

Cardiac ultrasound is a noninvasive technique that is commonly used to serially evaluate cardiac structure and function. Recent advances in Doppler-Echocardiography enable the ultrasonographer to perform a sophisticated noninvasive assessment of cardiovascular physiology. The Rhesus monkey is a frequently used non-human primate animal model of human cardiovascular disease because this species closely models human anatomy and physiology. However, while this species is frequently used in cardiovascular research, standardized echocardiographic values generated from large numbers of normal Rhesus are not available. In the present study, we performed cardiac ultrasound imaging on 28 healthy Rhesus monkeys to obtain normal reference values of cardiovascular structure and function in this species. Nomograms were generated from these data by plotting parameters of cardiovascular geometry and function with body weight. These normal reference data were compared to previously reported values obtained from prior studies that used noninvasive, invasive, and morphometric techniques.

Anesthetics, Dissociative↗
PubMed1996

Reference values for serum selenium in various areas-evaluated according to the TRACY protocol.

Published reports on selenium concentrations in serum and plasma were critically reviewed according to the criteria set up by the expert group of the international project TRACY. The aim was to examine both pre-analytical (sampling conditions and characteristics of the group) and analytical factors described in papers to establish reference values for evaluation of persons with deficiency or excessive exposure to the element. Out of 291 papers published during the period 1983 to 1993, which we reviewed, 36 were considered suitable for the TRACY project. In order to eliminate sources of variation due to age and health status, only data concerning healthy adults were retained. Of the sampling and other pre-analytical factors, geographical area and time of sampling were found to be of high importance. Gender, occupation, diet data and use of supplements or medications were also considered important determinants, but ethnic origin, smoking and fasting, contamination control and storage of sample were held to be of relatively low importance. Concerning analytical factors, accuracy criteria were generally satisfied although not extensively documented. Reference materials for serum selenium, which contribute to better analytical reliability have been available for over 10 years. Due to the geographical variation of selenium intake, one universal reference serum selenium value for the world's population was not feasible but the data selected allowed documentation of the serum selenium concentration levels among populations of different areas, mostly in Europe. Critical use of the published TRACY criteria in future papers will certainly extend their reliability and scientific significance.

Adult↗
PubMed1993

Reference values for the study of low doses of metals.

The role of biological monitoring (BM) in the prevention of exposure to toxic metals has currently acquired considerable importance. However, in the near future the usefulness of BM in occupational medicine could be reduced by the fact that exposure to toxic substances will progressively decrease and consequently problems of comprehension will occur. BM can maintain its importance in the prevention field if sensitivity and specificity of the biological indicators (BI) are increased and if this activity is specifically directed towards groups of subjects. To achieve this last goal, one of the problems which must be solved is the identification of "reference values" (RV) which define the BI levels in the general population not occupationally or environmentally exposed to the toxic substance under study. It is necessary to "refer" to these values in order to compare the data obtained in a population which is presumed to be exposed. In this presentation, the example of blood cadmium is used in order to discuss the criteria required to identify RV. Herein the data of a personal case list are reported, particularly the variables which must be considered when selecting subjects to form "reference groups". Conversely, the possibility of obtaining RV through meta-analysis studies, pooling the results published in international literature, are evaluated.

Adult↗
PubMed1993

Cerebral hemodynamics in subarachnoid hemorrhage evaluated by transcranial Doppler sonography. Part 2. Pulsatility indices: normal reference values and characteristics in subarachnoid hemorrhage.

In previous publications on the diagnostic value of transcranial Doppler sonography (TCD), conflicting results concerning predictive capacities for evaluating vasospasm by measuring flow velocities were reported, and the necessity to examine pulsatility indices (PIs) was stressed. PIs are known to give useful information on cerebral hemodynamics in cases of stenosis of the extracranial internal carotid artery and cerebral arteriovenous malformations. Whether the examination of PIs can give additional information in cases of subarachnoid hemorrhage (SAH) and allow prediction of impending delayed ischemic deficits (DIDs) is still unclear. Normal reference values for the Gosling pulsatility index, the Pourcelot resistance index, and the first Fourier pulsatility index were established in a series of 97 normal subjects. A significant increase in the indices was found as age increased, and there was a strong relation between the indices. There were no statistically significant differences between the right and left sides. An inverse relation was found between the flow velocity and PIs in the middle cerebral artery. In a prospective study of 455 follow-up TCD examinations in 66 SAH patients treated routinely with nimodipine, three different groups were analyzed separately: Group I, patients without DIDs; Group II, patients with DIDs; and Group III, patients with neurological deficits not strictly classifiable as DIDs. The analysis of all three groups together showed a typical time course after the onset of SAH: initially elevated PIs normalized around the tenth day after bleeding. According to Fisher grading, the amount of subarachnoid blood influences the increase in PIs significantly.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed2003

[The present status of convergence in PSA reference values--from the surveillance in the Tokai-Hokuriku district].

The number of patients with prostatic cancer is recently increasing in Japan and it is well known that serum PSA determination is routinely used as a tumor marker of prostatic cancer. However, the reference values of PSA are widely varied, because the reactivities of the antibody to free PSA and ACT-PSA are different in each kit. Thus, there is no compatibility among values determined by available kits. In this study, we sent a questionnaire on PSA determination to 180 hospitals with more than 200 beds. The recovery rate to the questionnaire was 80.5% (145/180) and the determination was performed in house at 47 hospitals out of 145. Stamey in Stanford University recommended to set the ratio of complex PSA to free PSA 9:1 in the reference material. It is expected that PSA ad hoc committee in Japan reported that the inter-kit variability is becoming small. It can be said that the standardization for PSA determination is progressing. To discriminate prostatic cancer from benign prostatic hypertrophy, free PSA ratio or complex ACT-PSA is recommended. Further accumulation of data on PSA will be necessary to confirm this matter.

Biomarkers, Tumor↗
PubMed1992

[Reference values for the echocardiographic calculation of left ventricular mass in normal children between the ages of 0 and 6].

BACKGROUND: Echocardiographic assessment of left ventricular mass (LVM) and mass/volume ratio (LVM/V) is an accurate method for evaluating left ventricular hypertrophy. However, reference values for LVM and left ventricular volume (V) in children under 6 years of age have not been well established. METHODS: Therefore, we evaluated 106 consecutive children (60 males, 46 females, mean age +/- SD 35 +/- 28 months, range 0-72) free of cardiovascular disease by clinical, electrocardiographic and echocardiographic examination. LVM and V were determined by M-mode echocardiography. RESULTS: The 5th and 95th percentile values of LVM were: 7 and 21 grams for infants aged 0 to 6 months; 13 and 32 grams for 7 to 24 months; 23 and 41 grams for 25 to 36 months; 23 and 59 grams for 37 to 48 months; 30 and 60 grams for 49 and 60 months; 36 and 98 grams for 61 and 72 months. The 5th and 95th percentile values of V were: 4 and 20 ml for infants aged 0 to 6 months; 12 and 36 ml for 7 to 24 months; 16 and 43 ml for 25 to 36 months; 20 to 55 ml for 37 to 48 months; 27 to 64 ml for 49 to 60 months; 39 to 74 ml for 61 to 72 months. The 5th and 95th percentile values of M/V ranged between 1 and 2.3 for infants aged 0 to 6 months, and 0.7-1.2 for those aged 61 to 72 months. LVM, V and LVM/V were significantly (p < 0.0001) related to age, height, weight and body surface area, but were unrelated to gender.

Aging↗
PubMed1999

Blood chromium determination in assessing reference values in an unexposed Mediterranean population.

Plasma chromium levels were determined in 243 healthy subjects. The study group consisted of 134 men and 109 women, ages 19-71 yr, all residing in Barcelona in northeastern Spain. The study was designed to assess the reference levels for plasma chromium and to investigate its relationships to age and sex. The assays were performed by means of a graphite-furnace atomic absorption spectrometer. The mean plasma chromium concentration was 3.01 +/- 1.45 nmol/L, ranging from 0.6 to 6 nmol/L. The upper reference values in the 0.95 percentile for this population was 5 nmol/L. No significant differences were observed with respect to the subjects' sex.

Adult↗
PubMed2000

Haematology and plasma biochemistry of Stamboek pre-pubertal gilts in Italy: reference values.

Blood samples were taken between February and April from 105 healthy Stamboek pre-pubertal gilts, aged 1-3 months, which were housed at a modern pig farm in northern Italy. The blood was analysed for nine haematological and nine selected haematochemical variables by means of automated and semiautomated blood analysis apparatus. After detection and rejection of outliers, the data were submitted to reference limits evaluation, also taking into account the limits for the red blood cell volume histogram as the anisocytosis index. Some haematological reference values deal with previously published data; in the haematochemical parameters, several discrepancies between evaluated limits and existing reference limits were noted, mainly for aspartate aminotransferase, alanine aminotransferase and lactate dehydrogenase levels and total protein concentration. The results confirm the relevance of age in determining blood reference intervals and that 'normal' values should be determined by each laboratory, taking into account the age of subjects, the sample size and methods of analysis.

Age Factors↗
PubMed2004

Critical evaluation of a high-throughput analytical method for polychlorinated biphenyls in human serum: which detector for the establishment of the reference values?

A rapid screening method, previously developed and validated for the determination of 60 PCB congeners in human serum by using high-resolution gas chromatography coupled with low-resolution mass spectrometry, was applied to the establishment of the reference values in the general population. The reliability of this method was further confirmed by analyzing ten serum samples, obtained from the same population group involved in the original study, by electron impact ionization with either low- or high-resolution mass spectrometry. Analyses in electron capture negative ionization mode were also performed for the determination of 'dioxin-like' isomers. The data were found to be in good accordance with one another, especially for the congeners of highest environmental significance. Then, 162 real serum samples were analyzed for the presence of PCBs. Comparison with the results from other studies reported in the literature showed that a similar profile was observed; the most abundant congeners were #153, #180, #138 and #170. A statistical analysis was performed to determine whether there were significant correlations between PCB concentrations and specific variables such as age, gender, and dietary habits.

Adult↗
PubMed1988

Urinary albumin excretion in healthy adult subjects: reference values and some factors affecting their interpretation.

A conventional radioimmunoassay has been used to measure urinary albumin concentration in overnight, recumbent and daytime, ambulant samples from 127 healthy, normotensive volunteers (mean age 33.3 yr SD 12.4; 59 males, 68 females). Reference values were obtained for urine albumin concentration (mg/l), albumin/creatinine ratio (mg/mmol), and albumin excretion rate (microgram/min). The frequency distributions of these variables were positively skewed, but became Gaussian on logarithmic transformation of the data. Albumin excretion was significantly higher in daytime, ambulant samples than in overnight, recumbent samples (p less than 0.001). Surface area was not correlated with urine albumin concentration but it was negatively correlated with urine albumin/creatinine ratio (p less than 0.05) due to the association between surface area and creatinine excretion. Urine albumin concentration was negatively correlated with age, but this was due to a higher urine flow rate in older subjects. There was no significant association with sex or with mean arterial blood pressure in the normal range. Two repeated measurements showed that variability was high and comparable for urine albumin concentration, albumin/creatinine ratio and albumin excretion rate: it was not significantly less in overnight, recumbent than in day-time, ambulant samples.

Adolescent↗
PubMed2007

Electrophysiological evaluation of motor pathways to proximal lower limb muscles: a combined method and reference values.

OBJECTIVE: In contrast with their important functional and clinical role, motor pathways to proximal muscles of lower limbs are rarely investigated in clinical neurophysiology. We describe a method to evaluate central and peripheral pathways to these muscles and report reference values. METHODS: Recording of both quadriceps was performed in 100 subjects. We analyzed the maximal M response after electrical stimulation of the femoral nerve, the patellar T reflex and the motor evoked potential (MEP) after transcranial magnetic stimulation. We defined the central motor conduction time as the difference between the MEP latency and the peripheral motor conduction time, estimated as the half of the T latency minus 0.5ms. RESULTS: The mean MEP latency is 20.6ms (SD 1.99ms), central motor conduction time 10.1ms (SD 1.29ms), MEP/M amplitude ratio 60.0% (SD 15.75%). Normal limits according to height and age are provided for each parameter and for interside asymmetry. CONCLUSIONS: This method to investigate the central and peripheral motor pathways supplying the L2-L4 myotomes is simple, painless and rapidly performed. The T reflex provides additional information on the proximal sensory pathways. SIGNIFICANCE: This method will be useful in many clinical conditions.

Adolescent↗
PubMed2000

Assessment of reference values for elements in human hair of urban schoolboys.

Hair samples of youngsters (3-15 years of age) from several urban areas of Rome were analyzed to determine the content of 19 minor and trace elements with the aim of assessing Reference Values (RVs). Thirteen essential elements were taken into account, Ca, Co, Cr, Cu, Fe, Mg, Mn, Mo, Ni, P, Se, V and Zn. On the other hand, Al, As, Cd, Pb, Sr and Ti were also evaluated on the basis of their potential toxicity. Procedures were developed for the collection, storage and pre-analytical treatment of samples. Measurements were performed by inductively coupled plasma atomic emission spectrometry. Subgroups were formed according to age and sex. Significant differences were found for certain elements depending on age and sex. This was the case, e.g., for Ca which showed a mean value of 336 mg/kg for males and of 537 mg/kg for females. The sex-dependent pattern for this element was also apparent when the three age subgroups of 3-6, 7-10 and 11-15 years were compared. The overall RVs obtained (mg/kg) are as follows Al, 10.2; As, 0.09; Ca, 450; Cd, 0.23; Co, 0.67; Cr, 0.99; Cu, 22.1; Fe, 19.0; Mg, 28.0; Mn, 0.35; Mo, 0.43; Ni, 1.49; P, 195; Pb, 7.11; Se, 0.77; Sr, 1.20; Ti, 0.79; V, 1.22; and Zn 150.

Adolescent↗