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PubMed2002

Reference values for 99mTc-MAG3 renography determined in healthy, potential renal donors.

BACKGROUND: Reference values for 99mTc-MAG3 renography were determined and the influence of sex and age (< 50/ > or = 50 years) was elucidated. METHODS: Sixty-eight potential renal donors were evaluated by renography among other tests. Through examination of their records 41 healthy subjects with a normal renal arteriography were included in this study and the reference values of the functional distribution (the split function, SF), the time to peak renal parenchymal activity (Tmax) and the residual activity (RA) were calculated. RESULTS: For Tmax there was no significant influence of sex or age. Mean RA increased significantly with age (20.5 vs. 23.2%, P = 0.03), but no difference was found between sexes. Mean SF (right kidney) was significantly higher among males. CONCLUSIONS: When a diuresis of at least 2 ml min-1 is demanded we found the following normal ranges: SF > 41%, Tmax < 4.3 min and RA < 33.7%.

Adult↗

PubMed2006

[The recommended reference values for anaemia in the elderly are of limited usefulness].

Recent epidemiological findings on the risk factors for mortality and functional impairment do not support lower cut-off values than the official WHO reference values for the definition of anaemia in the elderly, and even suggest higher limits. However, wide-scale application of such high Hb values for a full investigation of the causes of anaemia in clinical practice requires data on the effectiveness in terms of a net increase in quality of life at acceptable costs. At present, there are no evidence-based Hb limits for the elderly because such data are lacking. As a pragmatic way out, the WHO limits can be taken for a simple and non-invasive biochemical analysis of anaemia, but individual considerations, taking into account co-morbidity, life expectation and patients' preferences, are necessary for further diagnostic investigations such as colonoscopy or sternum puncture.

Aged↗

PubMed2001

[Reference values for lead in blood in urban population in southern Brazil].

OBJECTIVE: To describe the reference values for lead in blood in an urban population in the city of Londrina, in the state of Paraná, Brazil. MATERIALS AND METHODS: The reference population was composed of 520 adult volunteers who were assessed from November 1994 to December 1996. Exclusion criteria were: occupational exposure to lead, exposure through personal habits or practices, smoking more than 10 cigarettes per day, and living near industrial plants or other places that use lead in their production processes. Also excluded were individuals with abnormal clinical or laboratory results or with chronic diseases or cardiovascular disorders. Lead blood levels were determined using air-acetylene flame atomic absorption spectrophotometry. The detectable limit was 1.23 micrograms/dL. After the analyses of lead in blood, the following values were determined: minimum value, first quartile, median, third quartile, and maximum value; geometric mean; 95% confidence interval; experimental interval; and reference value. RESULTS: The reference values for lead in blood ranged from 1.20 micrograms/dL to 13.72 micrograms/dL. The geometric mean was 5.5 micrograms/dL. CONCLUSIONS: In general, the values found in this study are lower than those that have been reported for other countries. Additional data should be gathered from Brazilian populations living in more-industrialized areas.

Adult↗

PubMed1989

Criteria for reference value assessment of elements in human tissues.

The availability of updated and reliable reference values for elements in biological tissues and fluids plays a key role in the correct planning and performance of clinical, toxicological and environmental studies. The basic principles for a proper analytical approach in order to obtain such data are outlined. This in turn should significantly reduce the wide range of figures reported for most elements as "normal" intervals in the scientific literature. Some applications of these guidelines are illustrated in detail in the case of human lungs, liver and kidneys for which tentative reference values are assessed for a number of minor and trace elements, namely, Al, Ba, Cd, Cr, Cu, Li, Mg, Mn, Pb, Sr, V and Zn.

Humans↗

PubMed1999

Static lung volumes: reference values from a Latin population of Spanish descent.

BACKGROUND AND OBJECTIVES: The aim of this study was to develop a set of prediction equations and 90% confidence intervals for static lung volumes using the multibreath helium equilibration method from a sample of asymptomatic Caucasian subjects of Spanish descent. Moreover, these equations were compared with those of previous studies. METHODS: Measurements of static lung volumes using techniques recommended by the American Thoracic Society and the European Community for Steel and Coal were carried out on a selected sample of 591 healthy nonsmoking volunteers (305 men and 286 women) aged 18-88 years, living in the metropolitan area of Valencia, on the east coast of Spain. Multiple regression analysis using height, age and weight as independent variables were used to provide predicted values for both sexes. These reference values were compared with other sets of prediction equations reported in the literature using an independent sample of 69 subjects (32 men and 37 women). RESULTS: Simple linear regression equations using age, height and body weight predicted all the subdivisions of lung volumes (vital capacity, expiratory reserve volume (ERV), inspiratory capacity, functional residual capacity (FRC), residual volume (RV), total lung capacity (TLC), FRC/TLC and RV/TLC) as well as more complex equational models. The distribution of residuals fulfilled the assumptions of multiple regression analysis (independence, homoscedasticity and Gaussian distribution of residuals), except for ERV, using simple linear models. The derived equations did not differ significantly from most of the previously reported equations and were usually superior in their ability to predict the lung volumes. CONCLUSIONS: The use of the present prediction equations is recommended in the Latin population of Spanish descent and in populations with similar Caucasian characteristics.

Adolescent↗

PubMed1995

Reliability and adequacy of discharge diagnosis databases in the production of reference values.

Discharge diagnoses provide a possibility to select patients individually and then to establish reference values for both "pathological" and control groups. Currently, the available diagnostic information is still at its infancy and should be carefully evaluated before the reference values based on those groups are utilized. It is anticipated that electronic storage of diagnostic and therapeutic information will be applied more commonly in the future as the development of computers makes it easier. The advanced utilization of laboratory data challenges physicians both in the clinical and laboratory side to participate in this development in order to make the information systems serve their actual needs more closely.

Clinical Laboratory Information Systems↗

PubMed2006

Reference values for oxygen saturation by pulse oximetry in healthy children at sea level in Chennai.

UNLABELLED: There is little information on oxygen saturation (SaO2) values in children in developing countries. AIM: To determine the reference values for oxygen saturation by pulse oximetry in healthy children living at sea level in Chennai and aged between 1 mth and 5 yrs. DESIGN AND SETTING: A prospective study was conducted in Kanchi Kamakoti CHILDS Trust Hospital from February to May 2005. METHODS: A total of 626 healthy children aged between 1 mth and 5 yrs were examined for heart rate, respiratory rate and SaO2. RESULTS: The mean SaO2 levels for children in the age groups 1-3 mths, 3 mths to 1 yr, 1-3 years and 3-5 years were 98.5%, 98.8%, 98.9% and 99.1%, respectively. The overall mean and median SaO(2) values for the children in the different age groups were 99%. The mean -2 SD values of oxygen saturation in the age groups were 96.5%, 96.4%, 96.3% and 97.1%, respectively, with an overall mean of 96.6%. CONCLUSION: The reference value for mean SaO2 in healthy children aged between 1 mth and 5 yrs and living at sea level in Chennai city was 98.5% or more, but the -2SD values had a mean of 96.6%.

Aging↗

PubMed2005

Age and sex variability and normal reference values for the V(MCA)/V(ICA) index.

BACKGROUND AND PURPOSE: The index of mean blood flow velocity (V) in the middle cerebral artery (MCA) divided by respective velocity in the ipsilateral internal carotid artery (ICA), or V(MCA)/V(ICA) index, is commonly used as a marker of vasospasm, although reference values are not established. We sought to provide reference data for these velocities and index. METHODS: Transcranial color-coded duplex and carotid duplex sonography was performed in 335 healthy volunteers (211 women, 124 men; mean age +/- SD, 42 +/- 18 years; range, 18-86 years). Age analyses were based on three groups: I, <40; II, 40-60; and III, >60 years. The V(MCA)/V(ICA) index was calculated based on angle-corrected blood flow velocities determined in the MCA and extracranial ICA. RESULTS: Mean flow velocities in the MCA and ICA diminished with increasing age, most pronounced in those subjects >40 years. The V(MCA)/V(ICA) index increased significantly (1.67 + 0.005 [age]; P < .05) with age in women, but not in men. In women, reference values and ranges for the V(MCA)/V(ICA) index were as follows, by group: I, 1.82 (range, 0.88-2.68); II, 1.91 (range, 0.94-2.88); and III, 2.06 (range, 0.59-3.53). Respective values for men were as follows, by group: I, 2.10 (range, 0.96-3.24); II, 2.04 (range, 0.71-3.37); and III, 1.78 (range, 0.81-2.75). In subjects <40 years, the V(MCA)/V(ICA) index was significantly higher in men than in women. CONCLUSION: The V(MCA)/V(ICA) index significantly varies with age and sex. Sonographic diagnosis of cerebral vasospasm should be based on age- and sex-adjusted reference values of the V(MCA)/V(ICA) index.

Adolescent↗

PubMed2005

New reference values for echocardiographic dimensions of healthy Dutch children.

AIM: To renew the echocardiographic reference values of heart dimensions in healthy children. METHODS AND RESULTS: Group 1 consisted of 587 children, of which 361 boys and 226 girls, age from birth to 18 years, body weight over 2500 g, who visited the Pediatric Cardiology outclinic during the period January 2000 till March 2004. All included children were diagnosed as normal, or as having innocent heart murmur. The second group was taken from an earlier study and comprised 160 children (77 boys and 83 girls). The echocardiographic measures were taken from conventional M-mode recording of the left ventricle (LV) parasternal long axis view. End diastolic septal (IVS) and LV posterior wall thickness (LVPW) and end diastolic as well as end systolic LV intracavity dimensions were retrospectively analyzed. The regression lines from all measured sizes are significantly different from those collected in the early eighties. Especially the thickness of the IVS is smaller. The regression lines are independent of gender. CONCLUSIONS: New reference values have been found which should replace the presently used ones. There is no difference between boys and girls. Why the muscular wall thicknesses are thinner than found 20 years ago needs to be further explored.

Adolescent↗

PubMed2002

Blood lead reference values: the results of an Italian polycentric study.

This paper presents the results of a polycentric study carried out in seven different areas, organized by the Italian Society of Reference Values (SIVR) for assessing reference values of lead in blood (B-Pb) at the current doses of the metal to general population. The estimated arithmetic mean for B-Pb in males was of 45.1 microg/l and 30.6 microg/l in females; the 95th centile was 100 and 60 for males and females, respectively. The main variables influencing B-Pb levels were gender, age, BMI, outside sport practice, alcohol consumption and smoking habits, while the geographic area and the urban residence did not affect the metal concentration in blood.

Adolescent↗

PubMed1988

Methods for measurement of muscle function. Methodological aspects, reference values for children, and clinical applications.

In children isometric muscle force can be measured with acceptable reproducibility by using a simple hand-held dynamometer. Reference values for 10 different muscle groups are given for children aged 3.5-15 years. If age and weight are known, the force can be predicted. The most pronounced differences between the dominant and the non-dominant side were found in the elbow flexors, 3 of the 6 age groups showing greater force on the dominant side, and in the wrist extensors, the 2 oldest age groups being stronger on the dominant side. Sex differences were present as early as 9.5-11 years of age, boys being stronger than girls. Isokinetic muscle torque of the dorsiflexors of the ankle increased with age. Reference values are given for peak torque in children 6, 9, 12, and 15 years of age. The most intense force development occurs between 12 and 15 years of age in boys, and earlier in girls. Sex differences appear in early puberty. In young children the dominant leg was the stronger at the highest velocities. In the older children the non-dominant leg was the stronger at low velocities. Isokinetic measurements are time-consuming and require experience, and should be regarded as complementary to isometric testing. In muscle groups that are too weak to overcome gravity isometric and isokinetic methods cannot be used. Functional tests of motor ability are especially useful in patients with severely impaired muscle function when other test methods are inadequate or difficult to evaluate. The natural course of Duchenne muscular dystrophy was followed in 16 boys by means of functional tests, isometric tests, isokinetic tests of concentric muscle contraction, and manual tests. Of these only the isokinetic method proved unreliable, possibly because of difficulty in activating the muscles at different speeds. The function of adductor pollicis was studied by supramaximal electrical stimulation of the ulnar nerve. Force-frequency curves and reference values for relaxation rate and half contraction time to tetanus for children aged 9, 12, and 15 years are presented. The half contraction time to tetanus was briefer in the older children than in the younger. The relative force developed at a stimulation of 10 Hz increased with age. Apart for the increase in muscle force with increasing age, no other differences emerged between the different age groups. No sex differences were found. The electrical stimulation test is rather painful, and only about 60% of the children persevered to the end of the test.(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗

PubMed2003

Reference values of F wave parameters in healthy subjects.

OBJECTIVE AND METHODS: A large reference value database for F wave parameters was constructed with data from 121 to 196 healthy subjects; the age range of the subjects was 14-95 years. We studied the following parameters: minimum F wave latency (FMINLAT), mean F wave latency (FMEANLAT), maximum F wave latency (FMAXLAT), number of F waves/20 stimuli (FNUMBER) and F wave dispersion (FDISP=FMAXLAT-FMINLAT). The median, ulnar, peroneal and tibial nerves were studied. RESULTS: Height explains almost half of the FMINLAT variability. The F wave latency increases with height in the arms by 0.2 ms/cm and in legs 0.4 ms/cm. The effect of age on F wave latency in the arms is relatively small, only 0.03 ms/year; and in the legs age increases the FMINLAT by 0.1 ms/year. Gender does not affect FMINLAT in a systematic way. The peroneal nerve has slightly longer FMINLAT than the tibial nerve, while the FNUMBER is higher in the tibial nerve than the peroneal nerve. The differences between the ulnar and median nerve are slight. There is a very high correlation between all 3 latency parameters (FMINLAT, FMAXLAT and FMEANLAT), but no correlation between FDISP and FNUMBER and the other parameters. Side to side comparisons reveals no significant differences in any of the parameters except for the median nerve FMINLAT and FMEANLAT, which is 0.2 ms longer on the right than left. If side difference of more than 2 standard deviation is taken as the upper limit for normal, the side difference in arms is 1.4 ms and in legs 3 ms. In repeated studies the interexaminer variability is small; the correlation coefficient between the different F parameters is high (P>0.6 in arms and P>0.7 in legs). In the arms the upper limit for a significant difference of FMINLAT on repeated studies in the median nerve is 1.0 and 1.7 ms for the ulnar nerve. In the legs, FMINLAT for the peroneal nerve is 2.6 ms and for the tibial nerve is 2.1 ms. CONCLUSIONS: This large reference value database can be used not only to evaluate single measurements in relation with height and age, but also to compare right and left side and changes over time at repeated studies.

Adult↗

PubMedDate not supplied

Predictors and reference values of CD4 and CD8 T lymphocyte counts in pregnancy: a cross sectional study among HIV negative women in Zimbabwe.

OBJECTIVE: To identify predictors and define reference values for T lymphocyte subsets in HIV negative pregnant black women. DESIGN: Cross sectional study. SETTING: Edith Opperman Martenity Hospital, Harare, Zimbabwe. STUDY POPULATION: 1113 HIV negative women 22 to 35 weeks pregnant registering for routine antenatal care. METHODS: A questionnaire was used to collect demographic and obstetric data. CD4 and CD8 T lymphocyte counts were determined by manual immunocytochemistry. Concentrations in serum, of retinol, beta-carotene, ferritin, folate and 1-antichymotrypsin were also measured. Multiple linear regression analysis was employed to identify and estimate effects of potential predictors. MAIN OUTCOME MEASURES: CD4 and CD8 T lymphocyte levels, demographic, obstetric data and micronutrient status. RESULTS: Predictors of CD4 counts were gestational age, serum retinol and season. CD4 counts declined by 25 (95% confidence interval [CI]; 11 to 40; p = 0.001) cells/L for each week's increase in gestation among women with low serum retinol, while low serum retinol was independently associated with lower CD4 counts (-127; 95% CI, -233 to 20 cells/L; p = 0.02) at 35 weeks gestation. The late rainy season was associated with higher CD4 counts (137; 95% CI, 67 to 207 cells/L; p < 0.001). CD8 counts were higher in women with low serum folate (87; 95% CI, 6 to 166 cells/L; p = 0.036) and were slightly higher in gravida 4+ compared to gravida one to three. Reference values of CD4 but not CD8 count and percentage markedly differed from flow cytometry values of pregnant and non-pregnant women in developed and developing countries reported in the literature, even after controlling for the differences in methods of T lymphocyte subset immunophenotyping. CONCLUSION: Gestational age, gravidity, micronutrient status and season influence T lymphocyte subset levels and need to be considered when designing clinical management and intervention strategies for pregnant women. The data underscores the need for local reference values.

Adolescent↗

PubMed2003

Gestational age-dependent reference values for pH in umbilical cord arterial blood at term.

OBJECTIVE: Despite a change of fetal physiologic and biochemical functions with gestational age, stationary umbilical cord acid-base reference values are used as measures of obstetric care quality. The aim of this study was to assess the risk of low Apgar score relative to low pH when using stationary versus gestational age-adjusted reference values. METHODS: Umbilical artery pH was determined in 24,390 term singleton vaginal deliveries with a 5-minute Apgar score of 9 or greater. Low pH was defined as less than 7.10 as a stationary cutoff value, whereas pH less than (mean - 2 standard deviations [SDs]) was used when gestational age was considered. The 5-minute Apgar score less than 7 at low pH was studied in 44,978 term deliveries. RESULTS: A significant negative correlation was found between gestational age and umbilical artery pH. The odds ratio (OR) for pH less than 7.10 was continuously increasing, from 0.6 at 37 weeks to 1.5 at 42 weeks. In contrast, the OR for pH less than (mean - 2 SDs) was steady until 42 weeks, whereafter it increased (OR 1.24; 95% confidence interval 1.05, 1.47). A linear decrease of the association between Apgar score less than 7 and pH less than 7.10 with increasing pregnancy duration was found (P =.097), but for pH less than (mean - 2 SDs) there was no such association. CONCLUSION: We found a physiologic linear decline of umbilical artery pH with gestational age at term. Gestational age-adjusted umbilical cord artery pH reference values result in fewer diagnoses of cord acidemia than a stationary cutoff of pH less than 7.10.

Apgar Score↗

PubMedDate not supplied

Establishment of reference values for endocrine tests--part V: acromegaly.

BACKGROUND: Plasma insulin-like growth factor 1 (IGF-1) and the response of growth hormone (GH) to oral glucose are frequently used in the evaluation of patients suspected of acromegaly. Because of the implementation of new assay methodology for GH and IGF-1, we have established the reference values for these tests, as well as for urinary GH excretion. METHODS: From the general population, 50 subjects were recruited, equally distributed according to sex and age between 20 and 70 years. Two consecutive 24-hour urine samples were collected to determine urinary GH. Plasma IGF-1 was measured as well as the GH response during an oral glucose tolerance test (OGTT) with 100 g glucose. Basal plasma IGF-1 was also measured in 250 subjects recruited likewise from the general population who had participated in previous studies on reference values. RESULTS: The following reference ranges were established: urinary GH < 5-46 microU/24 h; nadir GH after OGTT < or =1.5 mU/l for males and < or =2.0 mU/l for females. IGF-1 was divided into age groups: 20-30 years 8-61 nmol/l; 31-40 years 8-41 nmol/; 41-50 years 7-36 nmol/l; 51-60 years 5-37 nmol/l; and 61-70 years 7-27 nmol/l. CONCLUSION: We have established reference values with state-of-the-art assay methodology for the diagnostic tests frequently used in the evaluation of patients suspected of acromegaly.

Acromegaly↗

PubMed2004

[Reference values of MRI flow measurements of the pulmonary outflow tract in healthy children].

PURPOSE: To provide reference values for MRI-based flow measurements in the main pulmonary artery in healthy children. MATERIALS AND METHODS: In 98 healthy children (age: 3 - 17 years, median: 11 years), the main pulmonary artery was examined using MRI-based flow measurements with high temporal resolution (9.6 ms per cardiac phase). RESULTS: The acceleration time revealed a distinct age dependency and varied between 90 and 155 ms (mean: 124 ms +/- 14). The relative acceleration time (related to the RR-interval) varied between 12.7 and 27 % (mean: 18 % +/- 2.6). The mean values and the standard deviations for the determined values were as follows: cardiac output (5.4 l/min +/- 1.4), cardiac output normalized to the body surface area (4.2 [l/min]/m(2) +/- 0.8), average systolic flow velocity (66 cm/s +/- 12), maximum systolic flow (309 ml/s +/- 79), mean flow (110 ml/s +/- 30), distensibility of the wall of the main pulmonary artery (79 % +/- 26), peak velocity (96 cm/s +/- 15), pressure gradient along the pulmonary valve (3.8 mm Hg +/- 1.2), stroke volume (63.2 ml +/- 17.9), acceleration volume (23.7 ml +/- 8.7), maximum acceleration of flow (4924 ml/s(2) +/- 1431), and reverse volume (0.2 ml +/- 0.3). CONCLUSIONS: The acquired values of reference are applicable to all pediatric patients and serve as a framework for the communication between the radiologist and the pediatric cardiologists. High temporal resolution of the measurement sequence is mandatory. Noticeable deviations of these values should induce additional (probably invasive) evaluation.

Adolescent↗

PubMed1999

Acquisition of improved reference values for cesium, iodine, strontium, thorium, and uranium in selected NIST reference materials.

As part of a study on the ingestion and organ content of some trace elements of importance in radiological protection, additional work has been undertaken to acquire improved reference values for cesium, iodine, strontium, thorium, and uranium in four selected reference materials provided by the US National Institute of Standards and Technology. The materials are SRM-1548 Total Diet, SRM-1548a Typical Diet, SRM-1486 Bone Meal, and RM-8414 Bovine Muscle. A coordinated study was undertaken with the help of seven selected laboratories in five countries. Instrumental and radiochemical neutron activation analysis and inductively coupled plasma-mass spectrometry were the analytical main techniques used.

Animals↗

PubMed2004

Femoral and whole-body bone mineral density in middle-aged and older Norwegian men and women: suitability of the reference values.

The aim of this study was to compare bone mineral density (BMD) in a population-based sample of middle-aged and older Norwegians, with reference values provided by the manufacturer of the densitometer (Lunar) in order to evaluate whether these reference values are suitable for Norwegians. Additional aims were to estimate the prevalence of osteoporosis. Bone mineral density of the hip and total body was measured by dual-energy X-ray absorptiometry in 2303 men and 3105 women 47-50 and 71-75 years old, respectively, in western Norway, as part of the Hordaland Health Study (HUSK). Of these, 3403 white individuals were free of medications or diseases known to influence bone metabolism (reference group). Compared with the Lunar reference population, men and older women had a slightly but significantly lower BMD of trochanter and total femur and middle aged women had significantly higher total body BMD. Except for the higher mean BMD of total body among middle-aged women and the uniformly lower BMD values of Ward's triangle, the deviations from the reference values of the manufacturer were less than 4%. Approximately 2.6% of middle-aged men vs 0.9% of middle-aged women were classified as osteoporotic on the basis of BMD of femoral neck. While the BMD values for femoral neck in this healthy Norwegian population are similar to the reference population of Lunar, the values of trochanter and total femur are lower in all groups except middle-aged women; however, the discrepancies are not of sufficient magnitude to warrant rejection of this commonly used database among Norwegians. Use of the young adult means from the Lunar reference database classified a higher proportion of middle-aged men than women as osteoporotic and osteopenic.

Age Distribution↗