scholarly journals Reference range: Which statistical intervals to use?

2020 ◽  
pp. 096228022096179
Author(s):  
Wei Liu ◽  
Frank Bretz ◽  
Mario Cortina-Borja
Keyword(s):  
Sample Size ◽  
Random Sample ◽  
Reference Range ◽  
Prediction Interval ◽  
Real Data ◽  
Reference Ranges ◽  
Tolerance Interval ◽  
Occurrence Probability ◽  
Clinical Laboratories ◽  
Key Points

Reference ranges, which are data-based intervals aiming to contain a pre-specified large proportion of the population values, are powerful tools to analyse observations in clinical laboratories. Their main point is to classify any future observations from the population which fall outside them as atypical and thus may warrant further investigation. As a reference range is constructed from a random sample from the population, the event ‘a reference range contains [Formula: see text] of the population’ is also random. Hence, all we can hope for is that such event has a large occurrence probability. In this paper we argue that some intervals, including the P prediction interval, are not suitable as reference ranges since there is a substantial probability that these intervals contain less than [Formula: see text] of the population, especially when the sample size is large. In contrast, a [Formula: see text] tolerance interval is designed to contain [Formula: see text] of the population with a pre-specified large confidence γ so it is eminently adequate as a reference range. An example based on real data illustrates the paper’s key points.

Thyroid-stimulating hormone reference range and factors affecting it in a nationwide random sample

2014 ◽  
Vol 52 (12) ◽  
Author(s):  
Ville L. Langén ◽  
Teemu J. Niiranen ◽  
Juhani Mäki ◽  
Jouko Sundvall ◽  
Antti M. Jula
Keyword(s):  
Risk Factor ◽  
Random Sample ◽  
Reference Range ◽  
Statistical Significance ◽  
Thyroid Stimulating Hormone ◽  
Thyroid Peroxidase ◽  
Healthy Population ◽  
Reference Ranges ◽  
And Gender ◽  
Stimulating Hormone

AbstractPrevious studies with mainly selected populations have proposed contradicting reference ranges for thyroid-stimulating hormone (TSH) and have disagreed on how screening, age and gender affect them. This study aimed to determine a TSH reference range on the Abbott Architect ci8200 integrated system in a large, nationwide, stratified random sample. To our knowledge this is the only study apart from the NHANES III that has addressed this issue in a similar nationwide setting. The effects of age, gender, thyroid peroxidase antibody (TPOAb)-positivity and medications on TSH reference range were also assessed.TSH was measured from 6247 participants randomly drawn from the population register to represent the Finnish adult population. TSH reference ranges were established of a thyroid-healthy population and its subpopulations with increasing and cumulative rigour of screening: screening for overt thyroid disease (thyroid-healthy population, n=5709); screening for TPOAb-positivity (risk factor-free subpopulation, n=4586); and screening for use of any medications (reference subpopulation, n=1849).The TSH reference ranges of the thyroid-healthy population, and the risk factor-free and reference subpopulations were 0.4–4.4, 0.4–3.7 and 0.4–3.4 mU/L (2.5th–97.5th percentiles), respectively. Although the differences in TSH between subgroups for age (p=0.002) and gender (p=0.005) reached statistical significance, the TSH distribution curves of the subgroups were practically superimposed.We propose 0.4–3.4 mU/L as a TSH reference range for adults for this platform, which is lower than those presently used in most laboratories. Our findings suggest that intensive screening for thyroid risk factors, especially for TPOAb-positivity, decreases the TSH upper reference limit.

New exact Bayesian prediction of the range for the exponential lifetime based on fixed and random sample sizes

2017 ◽  
Vol 6 (1-2) ◽  
pp. 169
Author(s):  
A. H. Abd Ellah
Keyword(s):  
Sample Size ◽  
Random Sample ◽  
Real Data ◽  
Predictive Distribution ◽  
Data Sets ◽  
Life Testing ◽  
Random Sample Size ◽  
Fixed Sample Size ◽  
Fixed Sample ◽  
Special Case

We consider the problem of predictive interval for the range of the future observations from an exponential distribution. Two cases are considered, (1) Fixed sample size (FSS). (2) Random sample size (RSS). Further, I derive the predictive function for both FSS and RSS in closely forms. Random sample size is appeared in many application of life testing. Fixed sample size is a special case from the case of random sample size. Illustrative examples are given. Factors of the predictive distribution are given. A comparison in savings is made with the above method. To show the applications of our results, we present some simulation experiments. Finally, we apply our results to some real data sets in life testing.

Radiologic Morphology of the Calcaneus

2013 ◽  
Vol 103 (1) ◽  
pp. 32-35 ◽  
Author(s):  
Pedro Gutierrez ◽  
Manuel Navarro ◽  
Margarita Ojeda
Keyword(s):  
Sample Size ◽  
Analysis Of Variance ◽  
Pitch Angle ◽  
Reference Range ◽  
Pediatric Population ◽  
T Test ◽  
Reference Ranges ◽  
Traumatic Injuries ◽  
The Mean

Background: The Fowler-Philip, calcaneal pitch, and total calcaneal angles define the radiologic morphology of the rearfoot. We studied these angles in healthy adolescents. Methods: We studied 141 feet. Patients with inflammatory or traumatic injuries were excluded. The mean participant age was 11.5 years. The Fowler-Philip, calcaneal pitch, and total calcaneal angles were measured on lateral weightbearing radiographs. The statistics included descriptive, sample size (α=0.05 and β=0.20), the Student t test, and analysis of variance; P < .05 was considered significant. Results: The samples were 141 and 35 radiographs for the Fowler-Philip and calcaneal pitch angles, respectively. Ninety percent, 25.1%, and 97.4% of the adolescents had normal Fowler-Philip, calcaneal pitch, and total calcaneal angles, respectively. In addition, 9.9%, 74.9%, and 2.6% of the values were outside the reference ranges, respectively. The Fowler-Philip angle decreased and the calcaneal pitch angle increased significantly with age (P = .0005). The total calcaneal angle did not change with age (P = .65). Conclusions: The mean angle values in a pediatric population did not differ from those in adults. We found a high percentage of calcaneal pitch angles outside the reference range. Age influenced the Fowler-Philip and calcaneal pitch angles but not the total calcaneal angle. (J Am Podiatr Med Assoc 103(1): 32–35, 2013)

Effects of Age and Health on the Euthyroid Reference Ranges for Serum Free Thyroxine and Free Triiodothyronine

1985 ◽  
Vol 24 (02) ◽  
pp. 57-65 ◽  
Author(s):  
J. E. M. Midgley ◽  
K. R. Gruner
Keyword(s):  
Lower Limit ◽  
Healthy Subjects ◽  
Thyroid Dysfunction ◽  
Reference Range ◽  
Free Thyroxine ◽  
Reference Ranges ◽  
Free Triiodothyronine ◽  
Serum Free ◽  
Young Subjects ◽  
Age Range

SummaryAge-related trends in serum free thyroxine (FT4) and free triiodothyronine (FT3) concentrations were measured in 7248 euthyroid subjects (age-range 3 months to 106 years). 5700 were patients referred to hospitals for investigation of suspected thyroid dysfunction, but who were diagnosed euthyroid. 1548 were healthy blood donors (age-range 18-63 years) with no indication of thyroid dysfunction. FT4 concentrations were little affected by the age, the sex or the state of health of the subjects in either group. Serum FT3 concentrations were significantly affected by both age and health factors. The upper limit of the euthyroid reference range for young subjects up to 15 years was about 20% higher (10.4 pmol/1) than for adult subjects older than 25 years (8.8 pmol/1). The change in the upper limits typical of young subjects to that typical of adults occurred steadily over the decade 15–25 years. After this age, little further change occurred, especially in healthy subjects. Additionally, the lower limit of the euthyroid range for FT3 was extended by the inclusion in the reference group of patients referred to hospitals. Compared with the lower limit of the FT3 range for healthy subjects (5 pmol/1), the corresponding limit for referred subjects (young or adult) was 3.5–3.8 pmol/1. Broadening of the FT3 reference range was probably brought about by a significant number of patients in the hospital-referred group with the “1OW-T3 syndrome” of mild non-thyroidal illness. Accordingly, FT3 was inferior to FT4 in the discrimination of hypothyroidism, as FT4 was unaffected by this phenomenon. Effects of age and non-thyroidal illness on serum FT3 concentrations require great care when selecting subjects for a laboratory euthyroid reference range typical of the routine workload. Constraints on the choice of subjects for FT4 reference ranges are less stringent.

Computerized method for validating laboratory reference ranges for triiodothyronine and thyroxin immunoassays

1991 ◽  
Vol 37 (3) ◽  
pp. 438-442 ◽  
Author(s):  
Brian Luttrell ◽  
Sall Watters
Keyword(s):  
Reference Range ◽  
Normal Values ◽  
Reference Group ◽  
Normal Population ◽  
Normal Subjects ◽  
Reference Ranges ◽  
Large Samples ◽  
Laboratory Reference ◽  
Euthyroid Status ◽  
Computer Based

Abstract We used a computer-based method to help validate the reference ranges of assays for triiodothyronine (T3) and thyroxin (T4). A retrospective search of a database of laboratory results for the previous six months identified all patients with apparent euthyroid status, as defined by methods independent of the immunoassay under review. A computer-generated reference group (CGR Group) of 2001 records had a gaussian distribution of T4 values and a reference range (mean +/- 2 SD) of 56-161 nmol/L, compared with the supplier's suggested range for euthyroid subjects (58-148 nmol/L) and an in-house range of 60-144 nmol/L for a group of 97 normal subjects. A similar CGR Group of 1902 records gave a reference range for T3 of 0.7-2.1 nmol/L (manufacturer's range 0.8-2.8; normal subjects 0.8-2.2). An attempt to devise a reference range for thyrotropin failed when we found that its concentration in the population of patients with normal values for thyroid hormones was distributed differently from that in the normal population. The method is intended to be used in addition to conventionally derived ranges based on results for healthy subjects. It allows the laboratory to conveniently verify the reference ranges for T3 and T4 assays at regular intervals by using very large samples with appropriate age, sex, and weight distribution, drawn from the population of patients' samples submitted for analysis.

scholarly journals Plasma mineral (selenium, zinc or copper) concentrations in the general pregnant population, adjusted for supplement intake, in relation to thyroid function

2020 ◽  
Vol 125 (1) ◽  
pp. 71-78
Author(s):  
Victor Pop ◽  
Johannes Krabbe ◽  
Wolfgang Maret ◽  
Margaret Rayman
Keyword(s):  
Thyroid Function ◽  
Reference Range ◽  
First Trimester ◽  
Future Research ◽  
Thyroid Peroxidase ◽  
Reference Ranges ◽  
Lower Plasma ◽  
The Mean ◽  
The Impact ◽  
Supplement Intake

AbstractThe present study reports on first-trimester reference ranges of plasma mineral Se/Zn/Cu concentration in relation to free thyroxine (FT4), thyrotropin (TSH) and thyroid peroxidase antibodies (TPO-Ab), assessed at 12 weeks’ gestation in 2041 pregnant women, including 544 women not taking supplements containing Se/Zn/Cu. The reference range (2·5th–97·5th percentiles) in these 544 women was 0·72–1·25 µmol/l for Se, 17·15–35·98 µmol/l for Cu and 9·57–16·41 µmol/l for Zn. These women had significantly lower mean plasma Se concentration (0·94 (sd 0·12) µmol/l) than those (n 1479) taking Se/Zn/Cu supplements (1·03 (sd 0·14) µmol/l; P < 0·001), while the mean Cu (26·25 µmol/l) and Zn (12·55 µmol/l) concentrations were almost identical in these sub-groups. Women with hypothyroxinaemia (FT4 below reference range with normal TSH) had significantly lower plasma Zn concentrations than euthyroid women. After adjusting for covariates including supplement intake, plasma Se (negatively), Zn and Cu (positively) concentrations were significantly related to logFT4; Se and Cu (but not Zn) were positively and significantly related to logTSH. Women taking additional Se/Zn/Cu supplements were 1·46 (95 % CI 1·09, 2·04) times less likely to have elevated titres of TPO-Ab at 12 weeks of gestation. We conclude that first-trimester Se reference ranges are influenced by Se-supplement intake, while Cu and Zn ranges are not. Plasma mineral Se/Zn/Cu concentrations are associated with thyroid FT4 and TSH concentrations. Se/Zn/Cu supplement intake affects TPO-Ab status. Future research should focus on the impact of trace mineral status during gestation on thyroid function.

scholarly journals The T4:TBG Ratio: A Re-Evaluation with Particular Reference to Low and High Serum TBG Levels

1982 ◽  
Vol 19 (2) ◽  
pp. 101-103 ◽  
Author(s):  
E C Attwood ◽  
G E Atkin
Keyword(s):  
Retrospective Study ◽  
Thyroid Function ◽  
Reference Range ◽  
High Serum ◽  
Reference Ranges ◽  
Thyroid Function Tests ◽  
Thyroxine Binding Globulin ◽  
Biochemical Investigation ◽  
Small Increments ◽  
Routine Assay

The thyroxine: thyroxine-binding globulin (T4: TBG) ratio is now an established part of the biochemical investigation of thyroid function. Reference ranges have been reported for euthyroid subjects with TBG levels within the range 6–16 mg/l. Routine assay of TBG on all thyroid function tests in this laboratory has suggested that, in patients with low or high TBG levels, the established reference ranges for T4:TBG may not be strictly applicable. A retrospective study has been made of a large number of thyroid function requests, including serum total T4, free T4, TBG, and TSH assays. Evidence is presented to show that in subjects with a TBG level of less than 8 mg/l the reference range for T4: TBG is elevated. Similarly, in subjects with a TBG greater than 16 mg/l, the reference range for T4: TBG is lowered. The data suggest that it is necessary to quote a T4: TBG reference range based on small increments of TBG levels or to relate total T4 reference ranges to those increments.

The Significance of Random Sample Size in Flow-Through Photometric Prescreening in Cervical Cytology

1976 ◽  
Vol 157 (2) ◽  
pp. 142-146 ◽  
Author(s):  
E. Sprenger ◽  
M. Schaden ◽  
D. Wagner ◽  
W. Sandritter
Keyword(s):  
Sample Size ◽  
Random Sample ◽  
Cervical Cytology ◽  
Random Sample Size ◽  
Flow Through

Paediatric reference range for overnight urinary cortisol corrected for creatinine

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Ole D. Wolthers ◽  
Mark Lomax ◽  
Anne Vibeke Schmedes
Keyword(s):  
Mass Spectrometry ◽  
Reference Range ◽  
Inhaled Corticosteroids ◽  
Prediction Interval ◽  
Geometric Mean ◽  
Urinary Free Cortisol ◽  
Urinary Cortisol ◽  
Cross Sectional ◽  
Systemic Activity ◽  
Free Cortisol

Abstract Objectives Systemic activity of inhaled corticosteroids (ICS) may be assessed via urinary cortisol measurement. Overnight urinary free cortisol corrected for creatinine (OUFCC) has been extensively reported in adult studies. However, a paediatric mass spectrometric (MS) reference range for OUFCC is not established. MS methods for OUFCC avoid cross-reactivity with other steroid hormones and are thus preferable to immunoassays. The aim of the present study was to define an MS OUFCC normative range in children. Methods This was a cross-sectional study of healthy pre-pubertal children from 5 to 11 years. Children collected urine from 10 pm or bedtime, whichever was earlier, until 8 am. Urinary free cortisol was measured via a liquid chromatography tandem mass spectrometry (LC-MS/MS) assay (Acquity UPLC with Xevo TQ-S Mass Spectrometer [Waters]) with in-house reagents. Urinary creatinine was measured using a commercial assay (Roche). Results Complete urine collections were obtained from 72 males and 70 females, mean age (SD) 8.6 (1.9) (range 5.0–11.8) years. The OUFCC 95% prediction interval was 1.7–19.8 nmol/mmol. Geometric mean OUFCC was 5.7; range 1.1–24.8 nmol/mmol. Conclusions The obtained normative LC-MS/MS OUFCC reference data facilitate the use of mass spectrometry OUFCC assays in assessment of systemic activity of endogenous and exogenous corticosteroids in children.

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