scholarly journals Calculation of indirect reference intervals of plasma lipase activity of adults from existing laboratory data based on the Reference Limit Estimator integrated in the OPUS::L information system

2021 ◽  
Vol 45 (2) ◽  
pp. 131-134
Author(s):  
Britta Amodeo ◽  
Aline Schindler ◽  
Ulrike Schacht ◽  
Hans Günther Wahl
Keyword(s):  
Information System ◽  
Lipase Activity ◽  
Clinical Chemistry ◽  
Laboratory Data ◽  
Direct Methods ◽  
Reference Interval ◽  
Reference Intervals ◽  
Specific Reference ◽  
Reference Limit ◽  
Reference Limits

Abstract Objectives Most laboratories have difficulties to determine their own reference intervals for the diagnostic evaluation of patient results by direct methods. Therefore, data is often just taken from the literature or package inserts of the analytical tests. Methods The section on Reference Limits of the German Society for Clinical Chemistry and Laboratory Medicine (DGKL) first uploaded the Reference Limit Estimator (RLE) as an R-program with MS Excel-interface on the DGKL home page and now this tool is implemented in the commercial Laboratory Information System OPUS::L (OSM AG Essen, Germany). We used this OPUS::L “Population specific Reference Limits” tool online with our laboratory database. First calculations were done using the example of lipase. Results The manufacturer’s original reference interval for lipase 12–53 U/L (adults) was changed to age dependent upper reference limits of <41 U/L (<20 years), <60 U/L (20–80 years) and <70 U/L (>80 years). Conclusions By means of the OPUS::L “Population specific Reference Limits” tool we were able to establish our laborarotry specific reference interval for plasma lipase activity. The new reference limits helped to solve an old problem of implausible low elevated lipase values.

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 Indirect methods for reference interval determination – review and recommendations

2018 ◽  
Vol 0 (0) ◽  
Author(s):  
Graham R.D. Jones ◽  
Rainer Haeckel ◽  
Tze Ping Loh ◽  
Ken Sikaris ◽  
Thomas Streichert ◽  
...  
Keyword(s):  
Clinical Chemistry ◽  
Direct Methods ◽  
Analytical Techniques ◽  
Reference Interval ◽  
Reference Population ◽  
Reference Intervals ◽  
Statistical Techniques ◽  
Indirect Methods ◽  
Indirect Approach ◽  
Patient Health

Abstract Reference intervals are a vital part of the information supplied by clinical laboratories to support interpretation of numerical pathology results such as are produced in clinical chemistry and hematology laboratories. The traditional method for establishing reference intervals, known as the direct approach, is based on collecting samples from members of a preselected reference population, making the measurements and then determining the intervals. An alternative approach is to perform analysis of results generated as part of routine pathology testing and using appropriate statistical techniques to determine reference intervals. This is known as the indirect approach. This paper from a working group of the International Federation of Clinical Chemistry (IFCC) Committee on Reference Intervals and Decision Limits (C-RIDL) aims to summarize current thinking on indirect approaches to reference intervals. The indirect approach has some major potential advantages compared with direct methods. The processes are faster, cheaper and do not involve patient inconvenience, discomfort or the risks associated with generating new patient health information. Indirect methods also use the same preanalytical and analytical techniques used for patient management and can provide very large numbers for assessment. Limitations to the indirect methods include possible effects of diseased subpopulations on the derived interval. The IFCC C-RIDL aims to encourage the use of indirect methods to establish and verify reference intervals, to promote publication of such intervals with clear explanation of the process used and also to support the development of improved statistical techniques for these studies.

scholarly journals First- and Second-Trimester Reference Intervals for Thyroid Hormones during Pregnancy in “Rhea” Mother-Child Cohort, Crete, Greece

2011 ◽  
Vol 2011 ◽  
pp. 1-12 ◽  
Author(s):  
Polyxeni Karakosta ◽  
Leda Chatzi ◽  
Emmanouil Bagkeris ◽  
Vasiliki Daraki ◽  
Dimitris Alegakis ◽  
...  
Keyword(s):  
Thyroid Hormones ◽  
Reference Interval ◽  
Reference Intervals ◽  
Thyroid Stimulating Hormone ◽  
Specific Reference ◽  
Reference Ranges ◽  
Thyroid Function Tests ◽  
Second Trimester ◽  
Free Triiodothyronine ◽  
Reference Limit

Estimation and interpretation of thyroid function tests in pregnant women is of utmost importance for maternal, fetal and neonatal health. Our objective was to calculate laboratory- and geography-specific reference intervals for thyroid hormones during pregnancy in an iodine-sufficient area of the Mediterranean, Crete, Greece. This project was performed in the context of “Rhea” mother-child cohort. Fulfillment of extensive questionnaires and estimation of free triiodothyronine (fT3), free thyroxine (fT4), thyroid-stimulating hormone (TSH), and antithyroid antibodies were performed. The reference population was defined using inclusion criteria regarding thyroidal, obstetric, and general medical status of women. Reference interval for TSH was 0.05–2.53 μIU/mL for the first and 0.18–2.73 μIU/mL for the second trimester. 6,8% and 5,9% of women in the first and second trimester, respectively, had TSH higher than the upper reference limit. These trimester-specific population-based reference ranges are essential in everyday clinical practice for the correct interpretation of thyroid hormone values and accurate classification of thyroid disorders.

Blood reference intervals for rabbits (Oryctolagus cuniculus) from routine diagnostic samples

2018 ◽  
Vol 46 (06) ◽  
pp. 393-398 ◽  
Author(s):  
Christoph Leineweber ◽  
Elisabeth Müller ◽  
Rachel E. Marschang
Keyword(s):  
Oryctolagus Cuniculus ◽  
Clinical Chemistry ◽  
Hematological Parameters ◽  
Blood Parameters ◽  
Reference Intervals ◽  
Specific Reference ◽  
Data Sets ◽  
Reference Limit ◽  
Statistical Program ◽  
Diagnostic Samples

Summary Objective: The goal of this study was to establish reference intervals for blood parameters in rabbits based on data from routine diagnostic samples. Materials and methods: Data sets from 1679–2039 values for clinical chemistry and 937–1559 values for hematological parameters were evaluated using the statistical program Reference Limit Estimator 20151017. Results: The following reference intervals were calculated for hematology: erythrocytes 4.37–7.43 × 1012 cells/l; hematocrit 0.28–0.48 l/l; hemoglobin 89.63–153.82 g/l; leucocytes 2.71–12.23 × 109 cells/l; neutrophils 0.87–7.82 × 109 cells/l; lymphocytes 0.36–6.58 × 109 cells/l; monocytes 0.08–1.71 × 109 cells/l; eosi nophils 0.07–0.19 × 109 cells/l; basophils 0.06–1.1 × 109 cells/l; thrombocytes 225.45–905.3 × 109 cells/l. Calculated intervals for clinical chemistries were: alkaline phosphatase 9.05–94.68 U/l; aspartataminotransferase 3.75–32.44 U/l; creatine kinase 1.63–559.53 U/l; γ-glutamyltransferase 2.5–14.46 U/l; glutamatdehydrogenase 0.68–14.78 U/l; fructosamin 248.08–501.43 µmol/l; bile acid 0.76–19.63 μmol/l; total protein 48.66–73.64 g/l; urea 2.63–10.28 mmol/l; creatinine 51.38–154.35 µmol/l; calcium 3.02–4.3 mmol/l; magnesium 0.66–1.51 mmol/l; phosphorus 0.54–2.18 mmol/l; sodium 132.61– 154.0 mmol/l and potassium 3.52–6.04 mmol/l. Conclusion and clinical relevance: The calculation of intervals based on a large number of routine diagnostic samples allows the establishment of labora tory specific reference intervals without the use of experimental animals.

EXPRESS: Method dependent variation in TSH and FT4 reference intervals in pregnancy: a systematic review

2021 ◽  
pp. 000456322110269
Author(s):  
O E Okosieme ◽  
Medha Agrawal ◽  
Danyal Usman ◽  
Carol Evans
Keyword(s):  
Systematic Review ◽  
Reference Interval ◽  
First Trimester ◽  
Reference Intervals ◽  
Assay Method ◽  
Specific Reference ◽  
Upper Limits ◽  
Wide Range ◽  
Assay Methods ◽  
In Pregnancy

Background: Gestational TSH and FT4 reference intervals may differ according to assay method but the extent of variation is unclear and has not been systematically evaluated. We conducted a systematic review of published studies on TSH and FT4 reference intervals in pregnancy. Our aim was to quantify method-related differences in gestation reference intervals, across four commonly used assay methods, Abbott, Beckman, Roche, and Siemens. Methods: We searched the literature for relevant studies, published between January 2000 and December 2020, in healthy pregnant women without thyroid antibodies or disease. For each study, we extracted trimester-specific reference intervals (2.5–97.5 percentiles) for TSH and FT4 as well as the manufacturer provided reference interval for the corresponding non-pregnant population. Results: TSH reference intervals showed a wide range of study-to-study differences with upper limits ranging from 2.33 to 8.30 mU/L. FT4 lower limits ranged from 4.40–13.93 pmol/L, with consistently lower reference intervals observed with the Beckman method. Differences between non-pregnant and first trimester reference intervals were highly variable, and for most studies the TSH upper limit in the first trimester could not be predicted or extrapolated from non-pregnant values. Conclusions: Our study confirms significant intra and inter-method disparities in gestational thyroid hormone reference intervals. The relationship between pregnant and non-pregnant values is inconsistent and does not support the existing practice in some laboratories of extrapolating gestation references from non-pregnant values. Laboratories should invest in deriving method-specific gestation reference intervals for their population.

Evaluation of Thyroid Function in Pregnant Women Using Automated Immunoassays

2021 ◽  
Author(s):  
K Aaron Geno ◽  
Matthew S Reed ◽  
Mark A Cervinski ◽  
Robert D Nerenz
Keyword(s):  
Pregnant Women ◽  
Equilibrium Dialysis ◽  
Reference Interval ◽  
First Trimester ◽  
Reference Intervals ◽  
Free Thyroxine ◽  
Specific Reference ◽  
Childbearing Age ◽  
Thyroid Autoantibody ◽  
The Impact

Abstract Introduction Automated free thyroxine (FT4) immunoassays are widely available, but professional guidelines discourage their use in pregnant women due to theoretical under-recoveries attributed to increased thyroid hormone binding capacity and instead advocate the use of total T4 (TT4) or free thyroxine index (FTI). The impact of this recommendation on the classification of thyroid status in apparently euthyroid pregnant patients was evaluated. Methods After excluding specimens with thyroid autoantibody concentrations above reference limits, thyroid-stimulating hormone (TSH), FT4, TT4, and T-uptake were measured on the Roche Cobas® platform in remnant clinical specimens from at least 147 nonpregnant women of childbearing age and pregnant women at each trimester. Split-sample comparisons of FT4 as measured by the Cobas and equilibrium dialysis were performed. Results FT4 decreased with advancing gestational age by both immunoassay and equilibrium dialysis. TSH declined during the first trimester, remained constant in the second, and increased throughout the third, peaking just before delivery. Interpretation of TT4 concentrations using 1.5-times the nonpregnant reference interval classified 13.6% of first trimester specimens below the lower reference limit despite TSH concentrations within trimester-specific reference intervals. Five FTI results from 480 pregnant individuals (about 1.0%) fell outside the manufacturer’s reference interval. Conclusions Indirect FT4 immunoassay results interpreted in the context of trimester-specific reference intervals provide a practical and viable alternative to TT4 or FTI. Declining FT4 and increasing TSH concentrations near term suggest that declining FT4 is not an analytical artifact but represents a true physiological change in preparation for labor and delivery.

scholarly journals Diurnal variation of leukocyte counts affects the indirect estimation of reference intervals

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Antje Torge ◽  
Rainer Haeckel ◽  
Mustafa Özcürümez ◽  
Alexander Krebs ◽  
Ralf Junker
Keyword(s):  
Diurnal Variation ◽  
Indirect Method ◽  
Venous Blood ◽  
Direct Methods ◽  
Reference Intervals ◽  
Indirect Methods ◽  
Indirect Estimation ◽  
Late Afternoon ◽  
Reference Limits ◽  
Leukocyte Counts

Abstract It has been observed that the estimation of reference intervals of leukocytes in whole venous blood leads to higher upper reference limits (uRLs) with indirect methods than has been reported in the literature determined by direct approaches. This phenomenon was reinvestigated with a newer, more advanced indirect method, and could be confirmed. Furthermore, a diurnal variation was observed with lower values during the morning and higher values in the late afternoon and at night. This observation can explain why indirect approaches using samples collected during 24 h lead to higher uRLs than direct methods applied on samples collected presumably in the morning.

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.

scholarly journals Impact of age, body weight and metabolic risk factors on steroid reference intervals in men

2020 ◽  
Vol 182 (5) ◽  
pp. 459-471
Author(s):  
Marco Mezzullo ◽  
Guido Di Dalmazi ◽  
Alessia Fazzini ◽  
Margherita Baccini ◽  
Andrea Repaci ◽  
...  
Keyword(s):  
Risk Factors ◽  
Reference Intervals ◽  
Metabolic Risk Factors ◽  
Specific Reference ◽  
Metabolic Risk ◽  
Cross Sectional ◽  
Cholesterol Ratio ◽  
Age Related ◽  
Reference Limits ◽  
17 Hydroxyprogesterone

Objective To evaluate the independent impact of age, obesity and metabolic risk factors on 13 circulating steroid levels; to generate reference intervals for adult men. Design Cross-sectional study. Methods Three hundred and fifteen adults, drug-free and apparently healthy men underwent clinical and biochemical evaluation. Thirteen steroids were measured by LC-MS/MS and compared among men with increasing BMI. Moreover, the independent impact of age, BMI and metabolic parameters on steroid levels was estimated. Upper and lower reference limits were generated in steroid-specific reference sub-cohorts and compared with dysmetabolic sub-cohorts. Results We observed lower steroid precursors and testosterone and increase in estrone levels in men with higher BMI ranges. By multivariate analysis, 17-hydroxyprogesterone and dihydrotestosterone decreased with BMI, while cortisol decreased with waist circumference. Estrone increased with BMI and systolic blood pressure. Testosterone decreased with worsening insulin resistance. 17-hydroxypregnenolone and corticosterone decreased with increasing total/HDL-cholesterol ratio. Age-related reference intervals were estimated for 17-hydroxypregnenolone, DHEA, 17-hydroxyprogesterone, corticosterone, 11-deoxycortisol, cortisol and androstenedione, while age-independent reference intervals were estimated for progesterone, 11-deoxycorticosterone, testosterone, dihydrotestosterone, estrone and estradiol. Testosterone lower limit was 2.29 nmol/L lower (P = 0.007) in insulin resistant vs insulin sensitive men. Furthermore, the upper limits for dihydrotestosterone (−0.34 nmol/L, P = 0.045), cortisol (−87 nmol/L, P = 0.045–0.002) and corticosterone (−10.1 nmol/L, P = 0.048–0.016) were lower in overweight/obese, in abdominal obese and in dyslipidaemic subjects compared to reference sub-cohorts, respectively. Conclusions Obesity and mild unmedicated metabolic risk factors alter the circulating steroid profile and bias the estimation of reference limits for testosterone, dihydrotestosterone, cortisol and corticosterone. Applying age-dependent reference intervals is mandatory for steroid precursors and corticosteroids.

Pediatric reference intervals for 1,25-dihydroxyvitamin D using the DiaSorin LIAISON XL assay in the healthy CALIPER cohort

2018 ◽  
Vol 56 (6) ◽  
pp. 964-972 ◽  
Author(s):  
Victoria Higgins ◽  
Dorothy Truong ◽  
Nicole M.A. White-Al Habeeb ◽  
Angela W.S. Fung ◽  
Barry Hoffman ◽  
...  
Keyword(s):  
Children And Adolescents ◽  
Critical Role ◽  
Reference Interval ◽  
Reference Intervals ◽  
Biologically Active ◽  
Specific Reference ◽  
Healthy Children ◽  
Serum Samples ◽  
Dihydroxyvitamin D ◽  
1,25 Dihydroxyvitamin D

Abstract Background: 1,25-dihydroxyvitamin D (1,25(OH)2D), the biologically active vitamin D metabolite, plays a critical role in calcium and phosphate homeostasis. 1,25(OH)2D is measured to assess calcium and phosphate metabolism, particularly during periods of profound growth and development. Despite its importance, no reliable pediatric reference interval exists, with those available developed using adult populations or out-dated methodologies. Using the fully automated chemiluminescence immunoassay by DiaSorin, we established 1,25(OH)2D pediatric reference intervals using healthy children and adolescents from the CALIPER cohort. Methods: Serum samples from healthy subjects (0 to <19 years) were analyzed for 1,25(OH)2D using the DiaSorin LIAISON XL assay and age-specific reference intervals were established. The Mann-Whitney U-test was used to determine seasonal differences. Pooled neonatal and infantile samples were quantified using liquid chromatography tandem mass spectrometry (LC-MS/MS) to determine if elevated concentrations during the first year of life may be attributed to cross-reacting moieties. Results: Three reference interval age partitions were required with highest levels in subjects 0 to <1 year (77–471 pmol/L), which declined and narrowed after 1 year (113–363 pmol/L) and plateaued at 3 years (108–246 pmol/L). 1,25(OH)2D concentration was not significantly affected by seasonal variation or sex. Elevated 1,25(OH)2D concentrations in neonatal and infantile samples may be the result of an interfering substance. The absence of 3-epi-1,25-dihydroxyvitamin D in the pooled samples makes it unlikely to be the interfering moiety. Conclusions: Pediatric reference intervals for 1,25(OH)2D were established to improve test result interpretation in children and adolescents. 1,25(OH)2D is elevated in a proportion of neonates and infants, which may be the result of a cross-reacting moiety.

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