scholarly journals Reference ranges for clinical electrophysiology of vision

2021 ◽  
Author(s):  
C. Quentin Davis ◽  
Ruth Hamilton
Keyword(s):  
Reference Values ◽  
False Negative ◽  
Reference Interval ◽  
Reference Intervals ◽  
Clinical Electrophysiology ◽  
Reference Ranges ◽  
Physiological Measurement ◽  
Negative Results ◽  
Reference Limits ◽  
Suitable Reference

Abstract Introduction Establishing robust reference intervals for clinical procedures has received much attention from international clinical laboratories, with approved guidelines. Physiological measurement laboratories have given this topic less attention; however, most of the principles are transferable. Methods Herein, we summarise those principles and expand them to cover bilateral measurements and one-tailed reference intervals, which are common issues for those interpreting clinical visual electrophysiology tests such as electroretinograms (ERGs), visual evoked potentials (VEPs) and electrooculograms (EOGs). Results The gold standard process of establishing and defining reference intervals, which are adequately reliable, entails collecting data from a minimum of 120 suitable reference individuals for each partition (e.g. sex, age) and defining limits with nonparametric methods. Parametric techniques may be used under some conditions. A brief outline of methods for defining reference limits from patient data (indirect sampling) is given. Reference intervals established elsewhere, or with older protocols, can be transferred or verified with as few as 40 and 20 suitable reference individuals, respectively. Consideration is given to small numbers of reference subjects, interpretation of serial measurements using subject-based reference values, multidimensional reference regions and age-dependent reference values. Bilateral measurements, despite their correlation, can be used to improve reference intervals although additional care is required in computing the confidence in the reference interval or the reference interval itself when bilateral measurements are only available from some of subjects. Discussion Good quality reference limits minimise false-positive and false-negative results, thereby maximising the clinical utility and patient benefit. Quality indicators include using appropriately sized reference datasets with appropriate numerical handling for reporting; using subject-based reference limits where appropriate; and limiting tests for each patient to only those which are clinically indicated, independent and highly discriminating.

Regional adjustment of thyroid hormone reference intervals

2014 ◽  
Vol 38 (5) ◽  
Author(s):  
Mira Ganslmeier ◽  
Claudia Castrop ◽  
Klemens Scheidhauer ◽  
Ina-Christine Rondak ◽  
Peter B. Luppa
Keyword(s):  
Reference Values ◽  
Reference Interval ◽  
Population Based ◽  
Reference Intervals ◽  
Clinical Findings ◽  
Reference Ranges ◽  
History Of ◽  
Study Population ◽  
Roche Diagnostics

AbstractWe conducted a study in a metropolitan area to establish regional reference intervals for thyreotropin (TSH) and the thyroid hormones free triiodthyronine (fT3) and free thyroxine (fT4). This was due to the different reference ranges, based on varying regional trials, presented for a widely used electrochemiluminescence immunoassay system.We investigated 292 apparently healthy adult subjects and excluded those with known history of thyroid disease, abnormal findings in the ultrasonographic examination of the thyroid gland, or elevated thyroid autoantibodies in serum. Accordingly, 204 of 292 subjects were included as the reference collective. We measured serum concentrations of TSH, fT3, and fT4 using the Elecsys assays from Roche Diagnostics and calculated the 2.5th and 97.5th percentiles.The nonparametrically calculated reference values for TSH and fT4 were 0.58–3.49 mIU/L and 11.58–20.46 pmol/L, respectively. Statistically remarkable is the finding of a normal Gaussian distribution of the fT3 serum concentration, leading to the parametric reference interval of 3.56–5.88 pmol/L.The established reference values for this regional collective showed tighter intervals than the reference ranges provided by the manufacturer. A carefully selected study population, based on the correspondent National Academy of Clinical Biochemistry criteria, ensured a valid set of reference ranges for TSH, fT3, and fT4, providing a basis for accurate in vitro thyroid testing. The 2.5th percentile for the fT3 is now in better accordance with clinical findings.

Impact of the reference values on the clinically-relevant cut-offs. The example of cortisol testing in children

2012 ◽  
Vol 50 (5) ◽  
Author(s):  
Julie Brossaud ◽  
Pascal Barat ◽  
Agnès Georges ◽  
Jean-Benoît Corcuff
Keyword(s):  
Reference Values ◽  
Reference Range ◽  
False Negative ◽  
Reference Ranges ◽  
Normal Range ◽  
Normal Reference Range ◽  
Negative Results ◽  
Basal Cortisol ◽  
False Negative Results ◽  
Morning Cortisol

AbstractAfter modification of our routine cortisol assay, we questioned the reference ranges for basal and stimulated cortisol plasma concentration in children.We retrospectively addressed the relevance of using the manufacturer’s normal reference range for basal cortisol and investigated its response to glucagon-betaxolol testing.Basal morning cortisol was 260 (98–604) nmol/L [manufacturer’s normal range (185–624) nmol/L: 26% subjects had “low” basal cortisol]. Upon testing cortisol increased to 502 (117–856) nmol/L. If a recently described 100% specificity threshold (403 nmol/L) is used it would amount to 31% adrenal insufficient children in apparently unaffected children. Basal and stimulated cortisol obtained with our prior radioimmunoassay (RIA) in a sub-group of subjects were lower: 411 (187–1061) and 770 (329–1542) nmol/L. Using the 403 nmol/L threshold with the radioimmunoassay would result in only 5% adrenal insufficient children.This shows again that laboratories have to advertise the need to establish reference values for given populations, both for basal or stimulated hormone levels. Failure to apply this rule will elicit false-positive and more critically, false-negative results.

scholarly journals Reference values of plasma homocysteine in Cuban children and adults

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Alina Concepción Alvarez ◽  
Ivette Camayd Viera ◽  
Lisy Vento Buigues ◽  
Yanet Fernández Martínez ◽  
Eraida Hernández ◽  
...  
Keyword(s):  
Reference Values ◽  
High Performance ◽  
Age Groups ◽  
Coffee Consumption ◽  
Reference Interval ◽  
Reference Intervals ◽  
Multifactorial Diseases ◽  
Weak Association ◽  
Different Populations ◽  
Cuban Population

AbstractObjectivesHomocysteine (Hcy) is a nonessential amino acid, produced by the demethylation of methionine. High Hcy levels, or hyperhomocysteinemia, have been associated with genetic and multifactorial diseases. Hcy reference values may vary between different populations, as Hcy levels are affected by factors such as sex, age, diet, smoking, and coffee consumption. The estimation reference interval (RI) allows to establish the normal values of this marker in population. At present, these levels are unknown in Cuba. The aim of this work is to estimate the Hcy reference intervals in Cuban children and adults.MethodsTotal Hcy concentration was quantified by high performance liquid chromatography (HPLC) in plasma. Hcy levels were evaluated in samples from 507 healthy individuals (260 children, 247 adults).ResultsRIs were estimated by nonparametric methods. We found significant differences between both age groups, but we did not find significant differences between sexes, within these groups. The established ranges were 2.56–14.55 µM and 3.63–17.19 µM for children and adults, respectively. Also, we observed a weak association between Hcy levels and age in both sex groups.ConclusionsThis is the first study that assesses Hcy reference values in Cuban population. Our results will allow the introduction of Hcy as a biochemical marker in laboratory testing.

Are the currently used reference intervals for creatine kinase (CK) reflecting the general population? The Tromsø Study

2012 ◽  
Vol 50 (5) ◽  
Author(s):  
Hallvard Lilleng ◽  
Stein Harald Johnsen ◽  
Tom Wilsgaard ◽  
Svein Ivar Bekkelund
Keyword(s):  
Creatine Kinase ◽  
General Population ◽  
Reference Interval ◽  
Reference Intervals ◽  
Control Analysis ◽  
Age Group ◽  
Background Population ◽  
Norwegian Population ◽  
Reference Limits ◽  
Laboratory Reference

AbstractLaboratory reference intervals are not necessarily reflecting the range in the background population. This study compared creatine kinase (CK) reference intervals calculated from a large sample from a Norwegian population with those elaborated by the Nordic Reference Interval Project (NORIP). It also assessed the pattern of CK-normalization after standardized control analyses.New upper reference limits (URL) CK values were calculated after exclusion of individuals with risk of hyperCKemia and including individuals with incidentally detected hyperCKemia after they had completed a standardized control analysis. After exclusion of 5924 individuals with possible causes of hyperCKemia, CK samples were analyzed in 6904 individuals participating in the 6th survey of The Tromsø Study. URL was defined as the 97.5 percentile.New URL in women was 207 U/L. In men <50 years it was 395 U/L and in men ≥50 years 340 U/L. In individuals with elevated CK, normalization grade after control analysis was inversely correlated to the CK level (p<0.04).URL CK values in women and in men <50 years of age were in accordance with URL CK values given by the NORIP. In men ≥50 years, a higher URL was found and the findings suggest an upward adjustment of URL in this age group.

Endocrine investigations and laboratory reference ranges

2020 ◽  
pp. 385-436
Author(s):  
Gary Butler ◽  
Jeremy Kirk
Keyword(s):  
False Negative ◽  
Risk Groups ◽  
Pituitary Hormones ◽  
Endocrine Disorders ◽  
Reference Ranges ◽  
Pubertal Stage ◽  
Optimal Outcomes ◽  
Negative Results ◽  
False Negative Results ◽  
Baseline Testing

While baseline testing may be appropriate in some endocrine disorders (e.g. hyper/hypothyroidism), many hormones are not secreted in a constant fashion (e.g. pulsatile (growth hormone), diurnal (cortisol)), and are also age (IGF-1) and pubertal stage (Luteinizing hormone/follicle-stimulating hormone/testosterone/oestradiol) dependent. In these circumstances, stimulation (or suppression) testing including using hypothalamic/pituitary hormones may be required. Testing can either be performed to identify occult endocrine dysfunction in high-risk groups, or alternatively to confirm (or exclude) endocrine disorders in conjunction with careful clinical assessment. These tests are, however, often complex and difficult to perform, with both false-positive and false-negative results, so careful and appropriate timing and choice of tests is required to ensure optimal outcomes.

scholarly journals SUN-222 Pre- and Post-Pubertal Reference Ranges for Oxygenated Androgens in Saliva

2020 ◽  
Vol 4 (Supplement_1) ◽  
Author(s):  
Joanne Adaway ◽  
Graeme Eisenhofer ◽  
Angela Huebner ◽  
Nils Krone ◽  
Malcolm McTaggart ◽  
...  
Keyword(s):  
Reference Interval ◽  
Reference Intervals ◽  
Range Data ◽  
Reference Ranges ◽  
Non Invasive ◽  
Premature Adrenarche ◽  
Upper Limits ◽  
Males And Females ◽  
Monitoring Treatment ◽  
Ovarian Syndrome

Abstract Oxygenated androgens such as 11 β-hydroxyandrostenedione (11OHA4) and 11-ketotestosterone (11KT) contribute significantly to the androgen pool in humans and their measurement has been shown to be useful in diagnosing disorders such as polycystic ovarian syndrome or premature adrenarche and also in monitoring treatment of congenital adrenal hyperplasia, alongside the classical androgens. Their measurement in saliva is particularly advantageous due to the non-invasive nature of sampling, meaning samples can easily be taken regularly to monitor treatment; however reference range data is not currently available for 11OHA4 and 11KT, limiting their clinical use. These analytes were measured in saliva samples from pre and post-pubertal males and females to inform reference ranges for these analytes. Samples collected into salivettes as part of the PRIMMS study (Technische Universität Dresden) were used for this work. A total of 130 samples (35 from pre-pubertal females, 43 from post-pubertal females, 42 from pre-pubertal males and 20 from post-pubertal males) were analysed for 11OHA4 and 11KT by LC-MS/MS. The ages of the participants ranged from 3.77 to 14.0 years in the pre-pubertal samples and 13.9-17.9 years in the post-pubertal samples. Pubertal status was determined clinically. The upper cut-off of the reference interval for 11OHA4 was 560 pmol/L in pre-pubertal females and 590 pmol/L in males, whilst 11KT had an upper limit of 216 pmol/L in females and 205 pmol/L in males. The upper limits of the ranges were higher in post-pubertal samples, with ranges of up to 1542 pmol/L in females and 1775 pmol/L in males for 11OHA4; the ranges for 11KT were up to 654 pmol/L for post pubertal females and 585 pmol/L for post-pubertal males. The data shows, as expected, a rise in the 11 oxygenated androgens post puberty. The upper limits of reference intervals for both analytes were very similar in males and females both pre- and post pubertally. These data can be used to inform clinical interpretation of the 11-oxygenated androgens; further work is required with larger cohorts of samples to develop more robust reference ranges.

scholarly journals Reference Intervals (RIs) of Lipid Parameters for Nepalese Population

2018 ◽  
Vol 6 (4) ◽  
pp. 366-372
Author(s):  
R.V. Mahato ◽  
R.K. Singh ◽  
A. M. Dutta ◽  
K. Ichihara ◽  
M. Lamsal
Keyword(s):  
Total Cholesterol ◽  
Reference Values ◽  
Clinical Laboratory ◽  
Local Population ◽  
Density Lipoprotein ◽  
Physical Exertion ◽  
Hdl Cholesterol ◽  
Reference Interval ◽  
Reference Intervals ◽  
Lipoprotein Cholesterol

Introduction: Reference interval (RIs) is the range of values provided by laboratory scientists in a convenient and practical form to support clinician in interpreting observed values for diagnosis, treatment and monitoring of a disease. Laboratories in Nepal uses RIs, provided in the kit inserts by the manufacturers or from the scientific literature, established for western/European population. It is well known that population across the globe differs physiologically, genetically; race, ethnically, lifestyle, food habits and diet which have great impact on the reference values. Thus, it is inappropriate to use RIs that do not represent the local population. This approach highlights for establishing reference values in Nepalese population using the IFCC-CRIDL guidelines published in (C28-A3). Objectives: The objective of this study is to analyze blood lipids concentration in apparently healthy Nepalese population to set up reference values for total cholesterol (TC), triglycerides (TG), High Density Lipoprotein-cholesterol (HDL-C) and Low Density Lipoprotein-cholesterol (LDL-C) and compare with the internationally recommended values. Methods: Reference individuals selected from healthy volunteers according to the IFCC/C-RIDL protocol in (C28 –A3). Volunteers were requested to avoid excessive physical exertion/exercise/excessive eating and drinking and fast overnight for 10-12 hour. Blood samples were collected from 120 subjects from each five centers of the country between 7:00-10:00 am, serum were separated and refrigerated at -20 in a cryo-vials. Finally, 617 samples were transported to Yamaguchi University, Graduate School of Medicine, Ube, Japan for analysis in dry Ice and 30 parameters were measured by fully automated biochemistry analyzer, Beckman Coulter (BC480) in the clinical laboratory. Results: A reference interval for each parameter was calculated from the 95% reference intervals ranging from 2.5% and 97.5% percentiles and, arithmetic mean + 2 SD were also calculated. The 95% reference range for total cholesterol (2.53-6.14), triglyceride was(0.42-3.32),for HDL Cholesterol was (0.28-1.46), for LDL was(1.05-4.00) and for VLDL was (0.054-0.92) for Nepalese population. Conclusion: Nepalese clinicians can take into consideration of reference lipid values of this study for diagnosis, treatment and monitoring of disease. Int. J. Appl. Sci. Biotechnol. Vol 6(4): 366-372

scholarly journals Reference Interval for Renal Profile parameters in North Indian Population from Rajasthan

2015 ◽  
Vol 1 (5) ◽  
pp. 233
Author(s):  
Dharmveer Yadav ◽  
Monika Gupta ◽  
Sandhya Mishra ◽  
Praveen Sharma
Keyword(s):  
Uric Acid ◽  
Reference Values ◽  
Indian Population ◽  
Reference Interval ◽  
Progressive Increase ◽  
Reference Intervals ◽  
North Indian Population ◽  
The North ◽  
Indian Origin ◽  
Objective Reference

Objective: Reference intervals are an essential part of laboratory medicine. Current study was planned to evaluate renal parameters in the healthy defined group of individuals which would serve as reference values of renal parameters for the North Indian population from Rajasthan.Design & Methods: Present study was conducted on 2021 apparently healthy individuals of North Indian origin ranging in age from 15-60 years, were selected randomly using defined criteria. Fasting samples were analyzed for Urea, Creatinine, Uric Acid, Sodium, Potassium and Chloride. Data were analyzed for middle 95 percentile (2.5th-97.5th percentile), median and 95% confidence interval using SPSS software package version 10.0.Result: RI for Urea, Creatinine and uric acid were lower in female (16-42mg/dl, 0.6-1.2mg/dl, 2.4-6.8mg/dl) as compared to male (17.00-44.35mg/dl, 0.7-1.5mg/dl, 2.8-7.2mg/dl). There was a progressive increase in urea, uric acid and Creatinine with increase in age. Though no appreciable differences could be observed in respect to most of renal parameters in rural versus urban, a wider range for uric acid was observed in urban population (2.50-7.20mg/dl). Except for Na+, K+ and Cl-, rest of parameters i.e. urea, creatinine, uric acid were higher range in obese as compared to non obese (17-45 Vs 17-44, 0.66-1.5 Vs 0.60-1.40, 2.5-7.4 Vs 2.5-7.0). Uric acid level was also found to be higher in non vegetarian population (2.6-7.5mg/dl).Conclusion: Findings of this study provide sex, age, BMI, habitat and diet specific renal function reference values to be used for North Indian population.

Partitioning biochemical reference data intosubgroups: comparison of existing methods

2004 ◽  
Vol 42 (7) ◽  
Author(s):  
Ari Lahti
Keyword(s):  
Reference Data ◽  
Reference Interval ◽  
Reference Intervals ◽  
New Method ◽  
Poor Correlation ◽  
Specific Reference ◽  
Common Reference ◽  
Reference Limits ◽  
The Common ◽  
The Ideal

AbstractFour existing methods for partitioning biochemical reference data into subgroups are compared. Two of these, the method of Sinton et al. and that of Ichihara and Kawai, are based on a quotient of a difference between the subgroups and the reference interval for the combined distribution. The criterion of Sinton et al. appears rather stringent and could lead to recommendations to apply a common reference interval in many cases where establishment of group-specific reference intervals would be more useful. The method of Ichihara and Kawai is similar to that of Sinton et al., but their criterion, based on a quantity derived from between-group and within-group variances, seems to lead to inconsistent results when applied to some model cases. These two methods have the common weakness of using gross differences between subgroup distributions as an indicator of differences between their reference limits, while distributions with different means can actually have equal reference limits and those with equal means can have different reference limits. The idea of Harris and Boyd to require that the proportions of the subgroup distributions outside the common reference limits be kept reasonably close to the ideal value of 2.5% as a prerequisite for using common reference limits seems to have been a major improvement. The other two methods considered, that of Harris and Boyd and the “new method” follow this idea. The partitioning criteria of Harris and Boyd have previously been shown to provide a poor correlation to those proportions, however, and the weaknesses of their method are summarized in a list of five drawbacks. Different versions of the new method offer improvements to these drawbacks.

scholarly journals DETERMINING REFERENCE RANGES FOR TREC AND KREC ASSAYS IN IMMUNE DEFICIENCY SCREENING OF NEWBORNS IN RUSSIAN FEDERATION

2019 ◽  
Vol 21 (3) ◽  
pp. 527-538
Author(s):  
M. A. Gordukova ◽  
I. A. Korsunsky ◽  
Yu. V. Chursinova ◽  
M. M. Byakhova ◽  
I. P. Oscorbin ◽  
...  
Keyword(s):  
Reference Interval ◽  
Reference Population ◽  
Dried Blood Spots ◽  
Reference Intervals ◽  
Asymmetric Distribution ◽  
Reference Ranges ◽  
Individual Values ◽  
Experimental Values ◽  
Deficiency Screening ◽  
Guthrie Cards

In this work, we used a reference population of newborns and sampled dried blood spots on Guthrie cards of 2,739 individual samples to determine the reference intervals for TRECs and KRECs values, in order to diagnose primary immunodeficiency by means of neonatal screening. The median absolute values for TRECs and KRECs were 195 (CI95%: 185-206) and 185 (CI95%: 176-197) copies per μl, respectively; the normalized value for TRECs was 2780 (CI95%: 2690-2840), and for KRECs, 2790 (CI95%: 2700-2900) copies per 2 × 105 copies of the albumin gene or 105 cells. The reference interval was calculated for 99 and 99.9 percentiles of total TRECs and KRECs individual values. Due to asymmetric distribution of data, the outliers were filtered off, using the Tukey’s criterion applied after logarithmic transformation of the data. When analyzing absolute values for TREC/KREC (per μL of blood), no “drop-down” TRECs values were identified; for KRECs, 18 experimental values were excluded from further analysis (from 9.8 to 13.5). The outlying values were not identified among the normalized values of TRECs/KRECs. The obtained reference values for TRECs and KRECs (at the 0.1 percentile level) were, respectively, 458 and 32 per 105 cells, or 23 and 17 per μl of blood samples from neonates.

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