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Seminars in Reproductive Endocrinology May 1996One of the primary aspects of any test is its capacity to distinguish "normal" from "abnormal." However, the issue of what normal truly is remains complex. There are two... (Review)
Review
One of the primary aspects of any test is its capacity to distinguish "normal" from "abnormal." However, the issue of what normal truly is remains complex. There are two categories: correlated normality and isolated normality. Each has numerous advantages and disadvantages, but the latter is much more common for defining normal. The method of establishing limits of normal varies depending on whether correlated or isolated normality is utilized. With correlated normality, the limits are dependent on whether the purpose of the test is discovery, exclusion, or confirmation. Isolated normality limits are frequently based on the consequences of being termed abnormal. It is imperative that normal limits be based on values of an appropriate reference group: the normal group should be healthy equivalents of the individual being tested. Finally, both intrapersonal and menstruational variations that result when multiple tests are performed on the same individual should be accounted for.
Topics: Diagnostic Tests, Routine; Humans; Reference Values; Reproducibility of Results
PubMed: 8796934
DOI: 10.1055/s-2007-1016319 -
Obstetrics and Gynecology Dec 2009To establish normal reference ranges during pregnancy for common laboratory analytes. (Review)
Review
OBJECTIVE
To establish normal reference ranges during pregnancy for common laboratory analytes.
DATA SOURCES
We conducted a comprehensive electronic database review using PUBMED and MEDLINE databases. We also reviewed textbooks of maternal laboratory studies during uncomplicated pregnancy.
METHODS OF STUDY SELECTION
We searched the databases for studies investigating various laboratory analytes at various times during pregnancy. All abstracts were examined by two investigators and, if they were found relevant, the full text of the article was reviewed. Articles were included if the analyte studied was measured in pregnant women without major medical problems or confounding conditions and if the laboratory marker was measured and reported for a specified gestational age.
TABULATION, INTEGRATION, AND RESULTS
For each laboratory marker, data were extracted from as many references as possible, and these data were combined to establish normal reference ranges in pregnancy. When possible, the 2.5 and 97.5 percentiles were reported as the normal range. In some of the reference articles, however, the reported range was based on the minimum and maximum value of the laboratory constituent. In those cases, the minimum to maximum range was used and combined with the 2.5 and 97.5 percentile range. We found that there is a substantial difference in normal values in some laboratory markers in the pregnant state when compared with the nonpregnant state.
CONCLUSION
It is important to consider normal reference ranges specific to pregnancy when interpreting some laboratory results that may be altered by the normal changes of pregnancy.
Topics: Female; Humans; Pregnancy; Reference Values; Statistics as Topic
PubMed: 19935037
DOI: 10.1097/AOG.0b013e3181c2bde8 -
Physiological Research Nov 2016Electrocardiography (ECG) in rats is a widely applied experimental method in basic cardiovascular research. The technique of ECG recordings is simple; however, the... (Comparative Study)
Comparative Study Review
Electrocardiography (ECG) in rats is a widely applied experimental method in basic cardiovascular research. The technique of ECG recordings is simple; however, the interpretation of electrocardiographic parameters is challenging. This is because the analysis may be biased by experimental settings, such as the type of anesthesia, the strain or age of animals. Here, we aimed to review electrocardiographic parameters in rats, their normal range, as well as the effect of experimental settings on the parameters variation. Furthermore, differences and similarities between rat and human ECG are discussed in the context of translational cardiovascular research.
Topics: Animals; Electrocardiography; Humans; Rats; Rats, Sprague-Dawley; Rats, Wistar; Reference Values
PubMed: 27429108
DOI: 10.33549/physiolres.933270 -
Journal of Manipulative and... Feb 2022The purpose of this study was to determine the normal range of rotation occurring during rotation stress testing for alar ligament integrity and to ascertain whether... (Observational Study)
Observational Study
OBJECTIVE
The purpose of this study was to determine the normal range of rotation occurring during rotation stress testing for alar ligament integrity and to ascertain whether rotation range on testing is affected by an individual's age.
METHOD
In this observational study, 88 people aged 18 to 86 years old with no current neck problems or known risk factors for craniocervical instability underwent rotation stress testing for the alar ligaments. The test was performed in each direction in neutral, flexion, and extension, with the participant both sitting and supine. Rotation range was recorded using an electromagnetic movement tracking system. Range was assessed overall and then compared by 10-year age groups using analysis of variance. Reliability of measurements was assessed by intraclass correlation coefficient and standard error of measurement.
RESULTS
Mean angles of upper cervical rotation ranged between 10.91° (standard deviation 3.38°) to 16.12° (standard deviation 5.13°). Overall measured rotation ranged from 1.37° to 33.22°. Participants in older age groups generally displayed reduced rotation; however, the reduction was less than 4°. Reliability of rotation measurements was good to excellent, with the intraclass correlation coefficient ranging from 0.80 to 0.99.
CONCLUSIONS
Normal range of rotation measured during stress testing for the alar ligament varied widely but did not exceed 33. All values measured in this study fell below recommendations for ligament integrity. Age-related change was not clinically significant in the interpretation of this test in this asymptomatic population.
Topics: Adolescent; Adult; Aged; Aged, 80 and over; Atlanto-Axial Joint; Biomechanical Phenomena; Humans; Ligaments, Articular; Middle Aged; Range of Motion, Articular; Reference Values; Reproducibility of Results; Rotation; Young Adult
PubMed: 35764470
DOI: 10.1016/j.jmpt.2022.03.023 -
AJR. American Journal of Roentgenology Dec 1998The objective of this study was to determine the normal range of dimensions for the liver, spleen, and kidney in healthy neonates, infants, and children.
OBJECTIVE
The objective of this study was to determine the normal range of dimensions for the liver, spleen, and kidney in healthy neonates, infants, and children.
SUBJECTS AND METHODS
This prospective study involved 307 pediatric subjects (169 girls and 138 boys) with normal physical or sonographic findings who were examined because of problems unrelated to the measured organs. The subjects were 5 days to 16 years old. All measured organs were sonographically normal. At least two dimensions were obtained for each liver, spleen, and kidney. Relationships of the dimensions of these organs with sex, age, body weight, height, and body surface area were investigated. Suggested limits of normal dimensions were defined.
RESULTS
Dimensions of the measured organs were not statistically different in boys and girls. Longitudinal dimensions of all three organs showed the best correlation with age, body weight, height, and body surface area. Height showed the strongest correlation of all. This correlation was a polynomial correlation.
CONCLUSION
Determination of pathologic changes in size of the liver, spleen, and kidney necessitates knowing the normal range of dimensions for these organs in healthy neonates, infants, and children. Presented data are applicable in daily routine sonography. Body height should be considered the best criteria to correlate with longitudinal dimensions of these organs.
Topics: Adolescent; Child; Child, Preschool; Female; Humans; Infant; Infant, Newborn; Kidney; Liver; Male; Prospective Studies; Reference Values; Spleen; Ultrasonography
PubMed: 9843315
DOI: 10.2214/ajr.171.6.9843315 -
Diabetes Research and Clinical Practice Feb 2020
Topics: Autonomic Nervous System; Diabetes Mellitus; Electrocardiography; Humans; Prognosis; Reference Values
PubMed: 30836133
DOI: 10.1016/j.diabres.2019.02.028 -
Respiratory Care Jan 2012Lung function parameters vary considerably with age and body size, so that, unlike many laboratory tests, the normal range of expected values must be individualized. For... (Review)
Review
Lung function parameters vary considerably with age and body size, so that, unlike many laboratory tests, the normal range of expected values must be individualized. For spirometry, only low values are considered to be abnormal, so the lower limit of normal (LLN) is taken to be equal to the 5th percentile of a healthy, non-smoking population. Simple and commonly used "rules of thumb," such as an FEV(1)/FVC < 0.70 to indicate air-flow obstruction, or assuming values < 80% of predicted to be abnormal, are inaccurate and will cause misclassification, specifically under-diagnosis of abnormalities in younger, taller individuals and over-diagnosis in those older or shorter. A much more accurate LLN for the FEV(1)/FVC ratio, which recognizes the change with age of this measurement, can be easily determined by subtracting 10 (10% or 0.10) from the age specific FEV(1)/FVC predicted for any individual. The analysis and mathematical descriptions of reference data have become increasingly sophisticated in recent years, but the interpretation of values near the LLN continues to carry uncertainty, due to an overlap in values between low normal values and those reflecting early disease. Among patients referred to a pulmonary function laboratory, the pre-test probability of disease may be relatively high, so that even individuals with values above the LLN may be more likely than not to have respiratory disease. A future goal for the pulmonary community would be the development of risk stratified outcome data that would allow an estimation of the probability of disease with progressive decrements in lung function. While interpreting spirometry results near the LLN will continue to be problematic, a more important task for the pulmonary community is to focus on finding the pool of individuals with clear-cut, but undiagnosed, COPD. And for this, good quality spirometry remains the best tool and must be widely available.
Topics: Humans; Lung Volume Measurements; Nutrition Surveys; Pulmonary Diffusing Capacity; Pulmonary Disease, Chronic Obstructive; Reference Values; Risk Assessment; Spirometry
PubMed: 22222132
DOI: 10.4187/respcare.01427 -
Postgraduate Medical Journal Nov 2018The NHS 'Choose Wisely' campaign places greater emphasis on the clinician-patient dialogue. Patients are often in receipt of their laboratory data and want to know...
The NHS 'Choose Wisely' campaign places greater emphasis on the clinician-patient dialogue. Patients are often in receipt of their laboratory data and want to know whether they are normal. But what is meant by normal? Comparator data, to a measured value, are colloquially known as the 'normal range'. It is often assumed that a result outside this limit signals disease and a result within health. However, this range is correctly termed the 'reference interval'. The clinical risk from a measured value is continuous, not binary. The reference interval provides a point of reference against which to interpret an individual's results-rather than defining normality itself. This article discusses the theory of normality-and describes that it is relative and situational. The concept of normality being not an absolute state influenced the development of the reference interval. We conclude with suggestions to optimise the use and interpretation of the reference interval, thereby facilitating greater patient understanding.
Topics: Diagnostic Tests, Routine; Humans; Models, Statistical; Physician-Patient Relations; Reference Values; Reproducibility of Results; Terminology as Topic
PubMed: 30425140
DOI: 10.1136/postgradmedj-2018-135983 -
JACC. Cardiovascular Imaging Jan 2021
Topics: Aged; Humans; Predictive Value of Tests; Reference Values; Ventricular Dysfunction, Left; Ventricular Function, Left
PubMed: 32861648
DOI: 10.1016/j.jcmg.2020.07.014 -
Cardiovascular Research Jan 2000
Review
Topics: Aging; Animals; Diagnostic Techniques, Cardiovascular; Female; Heart; Heart Rate; Humans; Male; Reference Values
PubMed: 10841627
DOI: 10.1016/s0008-6363(99)00322-3