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PubMed1979

Reference values for six enzymes in plasma from newborns and women at delivery.

We have determined the distribution in cord blood from healthy newborns of six enzymes: creatine kinase, lactate dehydrogenase, aspartate and alanine aminotransferase, alkaline phosphatase and gamma-glutamyltransferase. The concentration of enzymes were determined according to the methods recommended by the Scandinavian Committee on Enzymes. The distribution of isoenzymes and of enzymes in blood from women at delivery was investigated also. All distributions were positively skewed. The upper reference limits of cord blood exceeded those found in mother blood by a factor of eight for gamma-glutamyltransferase, and for lactate dehydrogenase and creatine kinase by a factor of two.

Alanine Transaminase↗
PubMed2004

Age- and sex-related reference values for serum insulin concentration and its biological determinants in a French healthy population. The STANISLAS cohort.

Insulin is involved in coronary heart disease through diabetes and metabolic syndrome. A great deal is known about insulin and its correlates, as well as factors related to changes in insulin. However, few studies consider the broad variety of correlates simultaneously. Therefore, the aims of the present study were to characterize the main factors of biological variation affecting serum insulin concentration and to establish reference limits of insulinemia in a presumably healthy French population. Insulin was measured using a microparticular enzymatic immunoassay. A total of 646 subjects aged 11-58 years from the STANISLAS cohort and divided into four groups of 162 males, 157 females, 163 boys and 164 girls, were included in the statistical analyses. In the whole population, serum insulin concentration varied from 0.80 to 54.60 microU/ml. Significant factors affecting insulin were age, gender, body mass index and glucose, in addition to alanine aminotransferase and high-density lipoprotein cholesterol in men, triglycerides and oral contraceptive use in women, and alkaline phosphatase in girls. In summary, we presented biological correlates of insulin in both healthy French male and female adults and children/adolescents and determined reference limits for insulin for each group. These results will contribute to a better interpretation of insulin data in further studies and laboratory investigations.

Adolescent↗
PubMed2005

Cerebroplacental Doppler ratio and adverse perinatal outcomes in intrauterine growth restriction: evaluating the impact of using gestational age-specific reference values.

OBJECTIVE: The purpose of this study was to compare the impact of using gestational age-specific reference levels of the cerebroplacental Doppler ratio (CPR) with categorical threshold in the prediction of adverse perinatal outcomes in growth-restricted pregnancies. METHODS: A retrospective cohort study of cases of intrauterine growth restriction over a 3-year period was conducted. The umbilical artery and middle cerebral artery pulsatility indices were converted to CPRs. The efficacy of using gestational age-specific reference levels of CPRs in predicting adverse outcomes was compared with the use of a CPR of less than 1.08. Adverse perinatal outcomes evaluated included cesarean delivery for nonreassuring fetal heart tones, umbilical artery pH less than 7.0, 5-minute Apgar scores less than 7.0, intraventricular hemorrhage greater than grade 2, periventricular leukomalacia, respiratory distress syndrome, and perinatal death. RESULTS: Of 183 pregnancies meeting our inclusion criteria, there were 70 with at least 1 adverse outcome. With the use of a CPR ratio below the 5th percentile for gestational age, the sensitivity, specificity, and positive and negative predictive values for predicting an adverse outcome were 65%, 73%, 73%, and 65%, respectively, with an odds ratio (95% confidence interval) of 5.2 (1.4-19.4; area under the receiver operating characteristic curve, 0.69). With a CPR threshold of less than 1.08, the sensitivity, specificity, and positive and negative predictive values were 72%, 62%, 68%, and 67%, with an odds ratio (95% confidence interval) of 4.2 (1.2-15.3; area under the receiver operating characteristic curve, 0.67). CONCLUSIONS: An abnormal CPR is associated with adverse perinatal outcomes in growth-restricted fetuses. The accuracy of using gestational age-specific reference levels was similar to that of using a categorical threshold.

Adult↗
PubMed2006

Reference values for median nerve conduction to the pronator quadratus.

OBJECTIVE: To derive a normative database for nerve conduction values of the median nerve to the pronator quadratus using a large and varied subject population. DESIGN: Descriptive study. SETTING: Private office or university-based clinic. PARTICIPANTS: Volunteers (N=207), recruited, without risk factors for neuropathy. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Onset latency, duration, amplitude, and area were recorded for all subjects. Side-to-side variability was calculated and the normative ranges were derived (97th percentile of observed values). RESULTS: Because the latencies increased with longer distances (longer forearms), the data were divided into 3 categories. The mean latency for those subjects whose distance from stimulator to recording electrode was 23 cm or less was 3.8+/-0.4 ms; the comparable values for those subjects with distances of 23.5 to 24.5 cm was 4.0+/-0.4 ms; and for those with distances of 25 cm and more, 4.5+/-0.4 ms. The amplitude and area varied with age. The mean amplitude for those subjects under 60 years of age was 4.4+/-1.8 mV, while those 60 years and over had an amplitude of 3.7+/-1.7 mV. The upper limit of normative side-to-side variability for latency was 0.6 ms, and the upper limit decrease in amplitude from 1 side to the other was 37%. CONCLUSIONS: This study establishes normative values for the median motor nerve conduction to the pronator quadratus.

Adult↗
PubMedDate not supplied

[Reference values for the concentration of free thyroxine and free triiodothyronine in the serum of euthyroid children].

Concentrations of free thyroxine (n = 341, male = 205, female = 136) and free triiodothyronine (n = 318, male = 198, female = 120) were determined using the radioimmunoassay method in blood serum of euthyroid children. Beyond the 30. day of life no significant differences were found in different age groups for the free thyroxine and free triiodothyronine concentration. The free thyroxine values of the infants in the range of 16.5-19.5 pg/ml decreased after the 30. day of life to the range of 15-17.5 pg/ml. In opposition to this trend free triiodothyronine values increased after the 30. day of life from the range of 2.5-3.3 pg/ml up to the range of 4.7-5.5 pg/ml.

Adolescent↗
PubMed2006

Development of an ELISA for myeloperoxidase on microplate: normal reference values and effect of temperature on specimen preparation.

BACKGROUND: Myeloperoxidase (MPO), a leukocyte enzyme, is implicated in both the pathogenesis and the progression of atherosclerosis. METHODS: We developed a sandwich ELISA on microplate using commercial antibodies for the measurement of plasma MPO. RESULTS: The in-house ELISA has a sensitivity of 15 ng/ml. Both within-day and between-day imprecision were <10%. The in-house assay was well correlated with the commercial kit from Oxis (gamma=0.96). We have established normal reference range for MPO for apparently healthy Chinese. No statistical difference was found between males and females and the various age groups. Because the coating antibodies used by two different kits are different in their affinities for MPO, the analysis by the in-house ELISA that was approximately three times that of the Oxis kit when testing the same specimens. We found that it is necessary to keep the heparinized whole blood on ice before centrifugation in order to prevent further release of MPO from the leukocytes at room temperature. For the same reason, serum is not recommended for MPO measurement. We also found that either pooled human plasma or serum containing MPO can be used as calibrators. CONCLUSIONS: We believe that this ELISA for MPO is useful to assess risk for inflammation, oxidative stress, nitrosative stress, and for predicting cardiac events.

Adult↗
PubMedDate not supplied

[Reference values of beta 2 microglobulin concentrations in the serum of children].

Concentrations of beta 2-microglobulin were determined using a competitive enzyme immunoassay in blood serum of 271 "healthy" children (male = 156, female = 115). The concentration of beta 2-microglobulin in children is age dependent. The values of the newborn 2.84-3.38 mg/l (95% confidence interval) decrease till the first year and stabilize later on between 1.48-1.56 mg/l (95% confidence interval).

Adolescent↗
PubMedDate not supplied

[Reference values for development of the iliac crest apophysis (Risser sign)].

PURPOSE: Actualization of the standard values for the maturation of the iliac bone apophysis by Risser. METHODS: The study analysed retrospectively 515 data from 154 patients of german descent with idiopathic scoliosis. The study group included 312 X-rays of 82 female and 203 X-rays of 72 male patients, born between 1970-1985 and within the age of 10 and 20 years at the time of the evaluation. The middle chronological age, the standard deviation, the difference between female and male patients as well as the t-value were calculated for each stage. In addition the intervals with the corresponding t-values were calculated. RESULTS: The middle chronological age calculated for the stages of Risser shows significant differences. Because of acceleration the ossification begins earlier and finishes later. As assumed, the standard values were different for female and male patients. CONCLUSION: The necessity of a new and complete investigation was given because of the acceleration of the maturation and the incomplete existing standard values. CLINICAL RELEVANCE: This study contains current standard values for maturation of the iliac bone, which could be applied for analysing the skeletal maturation.

Adolescent↗
PubMed1991

Enzyme immunoassay of serum erythropoietin in healthy children: reference values.

A solid phase enzyme immunoassay for erythropoietin which required only a small specimen of blood was evaluated. It permitted measurement up to 150 IU/L. Recovery was between 86.2% and 110.0% and between-batch precision between 4.7% and 5.7%. We determined the levels of erythropoietin in infants aged 10 months (geometric mean 11.2 IU/L; 95% range 3.6-34.9) and in children aged 2 years (geometric mean 10.5 IU/L; 95% range 4.3-25.8). Both were significantly higher than the values found in children aged 4 years (geometric mean 7.2 IU/L; 95% range 2.4-21.8). There were no differences between the values in children at 4 years, those aged 4-15 years and adults.

Adolescent↗
PubMed1989

[Reference value of glutamic transaminase to prevent non-A non-B post-transfusion hepatitis].

GPT is currently used as a surrogate test for detection of the non-A, non-B carrier state. Among the patients who received the blood at least one blood unit from donor with relatively high level of GPT (26-35 KU), incidence of post-transfusion NANB hepatitis was higher than that of the patients who received only blood with low level of GPT (less than or equal to 25 KU). It is expected that introduction of lower GPT cut-off value will substantially reduce the incidence of post-transfusion NANB hepatitis. We reviewed several factors, such as gender, age and body weight that could potentially affect GPT activity, using the data of 40,967 regular blood donors for GPT who donated at Fukuoka Red Cross Blood Center from October to November, 1987. The upper limit of normal GPT for males is significantly higher than that of females. GPT values in both males and females progressively increase with the age and body weight. It would therefore seem that gender, age and body weight should be taken into account in resetting of GPT cut-off values to prevent post-transfusion NANB hepatitis.

Adolescent↗
PubMed1989

[Reference values for the pulsatility index and the resistance index of blood flow curves of the umbilical artery and fetal aorta in the 3d trimester].

In 209 pregnancies without complications we recorded blood velocity waveforms of the umbilical artery and the foetal aorta between 29 and 42 weeks of gestation by means of a Duplex-pulsed Doppler system (umbilical artery: n = 276; foetal aorta: n = 244). We calculated the pulsatility index (PI) and the resistance index (RI). Both indices were normally distributed. The regression lines and reference ranges for the 95% confidence intervals are shown. The PI as well as the RI of waveforms of the umbilical artery demonstrated a significant fall with increasing gestation. The PI of the foetal aorta demonstrated a gentle, non-significant fall; RI showed no changes throughout the third trimester. Comparisons with the reference ranges published by other authors are discussed.

Blood Flow Velocity↗
PubMed2006

[Accuracy of different body mass index reference values to predict body fat in adolescents].

This study evaluates the accuracy of cutoff points in the body mass index (BMI) for identifying adolescents with overweight, compared to the percentage of body fat, estimated by electric bioimpediance, in a probabilistic sample of 610 adolescents from 12 to 19 years of age (222 boys and 388 girls) enrolled in public schools in Niterói, Rio de Janeiro, Brazil. ROC was used to evaluate the sensitivity and specificity of BMI cutoffs from one Brazilian, two North American, and one international reference. The cutoff points in the study sample were lower than the other references, with 76% to 95% sensitivity and 75% to 95% specificity. The Brazilian cutoff points were also more sensitive (53% to 100%) as compared to the other references (40% to 86%). The international parameter showed better sensitivity for older adolescents, and the Northern American references for younger adolescents. BMI was a good proxy for adiposity, but cutoff points from other population references should be used with caution, since they can lead to classification errors in adolescents with overweight.

Adiposity↗
PubMed2000

Lung function reference values in Chinese children and adolescents in Hong Kong. I. Spirometric values and comparison with other populations.

As part of a comprehensive evaluation of lung function in Hong Kong-born Chinese children and adolescents, this study was conducted to determine updated prediction equations for spirometry, to evaluate the secular changes of lung function during the past decade, and to compare these results with other data sets. The results are based on 852 (392 male, 460 female) healthy students, age 7 to 19 yr, recruited from seven schools in Hong Kong. All were born and lived in Hong Kong, nonsmokers, free from past or present symptoms or diseases affecting the respiratory tract. A body plethysmograph was used to record lung function measurements. Natural logarithmic values of lung volumes and body height were used in the final regression model. Prediction equations for FVC, FEV(1), and maximal expiratory flow at 50% of the FVC (MEF(50)) for both sexes are presented, with standing height as the dependent variable. Compared with Hong Kong data from 1985, the results show a significant increase in height-corrected FVC and FEV(1) in both boys and girls, over the whole height range. Compared with recent data of whites, FVC in boys were 8 to 10% lower in the study population, and the difference increased to 12% above the 165 cm height ranges, while FVC in Chinese girls had similar or only slightly lower predicted values. FEV(1) values showed a similar pattern with lesser difference between the two ethnic groups. Compared with recent data from Chinese children in Singapore, a similar pattern with overall lesser difference of the two populations was present in boys, whereas there was no significant difference between girls in the two places. Our findings support the conclusion that exogenous factors may contribute significantly to the differences in lung function values among ethnic groups and that it is important to examine normative values of various populations for secular trends.

Adolescent↗
PubMed2007

Pediatric reference values for molecular markers in hemostasis.

BACKGROUND: The hemostatic system is a developing and changing process relative to age. OBJECTIVES: To distinguish the differences in hemostatic parameters between children and adults, and to establish the normal range of these parameters in children of different age groups. DESIGN/METHODS: Blood was obtained from healthy children aged 1 to 18 years (n=70) and adults (n=26). Children were categorized into 3 age groups: 1 to 5 years, 6 to 10 years, and 11 to 18 years. Several coagulation and fibrinolysis parameters were determined. RESULTS: Children in all age groups showed no significant difference in mean levels of von Willebrand factor antigen and activity, activated partial thromboplastin time, fibrinogen, activated factor VII, tissue plasminogen activator, plasminogen activator inhibitor-1, and thrombin activatable fibrinolysis inhibitor compared with adults. However, children aged 1 to 5 years had significantly higher mean values of soluble thrombomodulin (P=0.001), prothrombin time (P=0.03), tissue factor (P<0.001), thrombin-antithrombin complex (P<0.001), and D-dimer (P=0.009) whereas they had significantly lower mean levels of protein C activity (P=0.02) than did adults. CONCLUSIONS: These data indicate physiologic differences in the hemostatic system between children and adults and should serve as a useful reference guide in interpreting test results for children with suspected bleeding disorders.

Adolescent↗