Where does subclinical hypothyroidism start?

2005 ◽  
Vol 44 (02) ◽  
pp. 56-61 ◽  
Author(s):  
G. Wunderlich ◽  
Th. Grüning ◽  
R. Koch ◽  
H. Döge ◽  
J. Kotzerke ◽  
...  
Keyword(s):  
Reference Range ◽  
Clinical Biochemistry ◽  
Reference Group ◽  
Reference Population ◽  
Total Study Population ◽  
Autoimmune Thyroid ◽  
Reference Limit ◽  
Study Population ◽  
Definition Of ◽  
Upper Reference Limit

SummaryThe upper limit of the TSH reference range is currently under discussion. In its recent guidelines, the National Academy of Clinical Biochemistry (NACB) recommended the use of ~2.5 mIU/L, rather than ~4 mIU/L, due to the fact that reference populations, on which the definition of the reference range is based, contain persons undergoing an initial phase of autoimmune thyroid disease. This will skew the upper reference limit of TSH. Ultrasonography, in addition to measurement of thyroid autoantibodies, should be used to exclude these persons. Objective: The present study investigates whether the NACB recommendation also applies for a region of mild iodine deficiency. Methods: According to NACB criteria, a reference population (713 persons) was defined out of a total study population of 1442. The TSH reference range was calculated in this reference group and in further subgroups by percentiles. The results were compared with the total study population and the NACB recommendation. All assays used were provided by BRAHMS Diagnostica AG, Hennigsdorf, Germany. Results: As expected, all median TSH values, excluding the median of the group with a hypoechogenic thyroid were close to 1.2 mIU/L. The 97.5th percentile in the reference population was 3.35 mIU/L. However, there was no difference compared to the total study population. Conclusion: The upper reference limit for TSH based on a reference population according to NACB criteria came down to 3.35 mIU/L, but not to ~2.5 mIU/L. Interestingly, there is no difference compared to the total study population.

Clinical and analytical evaluation of kits for measurement of creatine kinase isoenzyme MB.

1986 ◽  
Vol 32 (1) ◽  
pp. 186-191 ◽  
Author(s):  
T R Koch ◽  
U J Mehta ◽  
H C Nipper
Keyword(s):  
Creatine Kinase ◽  
Clinical Performance ◽  
Reference Population ◽  
Reference Ranges ◽  
Diagnostic Specificity ◽  
Electrophoretic Method ◽  
Reference Limit ◽  
Coronary Care ◽  
Upper Reference Limit ◽  
Creatine Kinase Isoenzyme Mb

Abstract We studied the analytical and clinical performance of six methods for creatine kinase (EC 2.7.3.2) isoenzyme MB (CK-MB): three immunoassays (Behring, Hybritech, and International Immunoassay Labs); one immunoinhibition assay (Roche); one immunoinhibition/column method (Du Pont); and one electrophoretic method (Beckman). Between-day precision for all kits was poor at the upper reference limit. All methods gave results linearly related to CK-MB concentration and all were free from CK-MM, CK-BB, and adenylate kinase interference. Only the Du Pont method was adversely affected by atypical isoenzymes. For diagnosis of acute myocardial infarction in a coronary care population (n = 40; prevalence = 45%), all methods were approximately 95% efficient, when appropriate reference criteria were used. Some manufacturers fail to provide data for an appropriate (acutely ill, non-infarct) reference population; decreased diagnostic specificity may result from use of reference ranges based on results for healthy subjects. Expression of CK-MB as a percent of total CK degrades efficiency unless total CK is markedly increased.

scholarly journals Definition of the upper reference limit of glycated albumin in blood donors from Italy

2017 ◽  
Vol 56 (1) ◽  
Author(s):  
Chiara Bellia ◽  
Martina Zaninotto ◽  
Chiara Cosma ◽  
Luisa Agnello ◽  
Bruna Lo Sasso ◽  
...  
Keyword(s):  
Blood Donors ◽  
Glycated Albumin ◽  
Specific Reference ◽  
Reference Limit ◽  
Percentile Method ◽  
The Mean ◽  
Definition Of ◽  
Upper Reference Limit ◽  
Mean Glucose

AbstractBackground:Glycated Albumin (GA) has been proposed as a short-term indicator of glycemic homeostasis. The aim of this study is to describe the distribution of GA in a large sample of blood donors from Italy to evaluate whether demographic features, namely age and sex, could influence GA levels and define specific reference limits.Methods:The study included 1334 Italian blood donors. GA was measured using an enzymatic method (quantILab Glycated Albumin, IL Werfen, Germany). The upper reference limit (URL) was calculated using the non-parametric percentile method.Results:A modest, although significant, increase of GA was observed in relation to age (p<0.001), especially in males, where the differences were more pronounced (p<0.001 in males, p=0.003 in females). Slight differences were documented based on sex (12% [11.3–12.8] in males; 12.2% [11.4–13.1] in females; p=0.01). After excluding individuals with fasting plasma glucose ≥7 mmol/L, the calculated GA URL was 14.5% (95% CI: 14.3–14.7). Subjects with GA>14.5% presented a mean age of 48.4±12.2 years, 66.7% were males and the mean glucose was 6.88±2.5 mmol/L.Conclusions:GA in Caucasians shows a similar increasing trend at older ages documented in other ethnicities. The definition of the URL in this population could be useful for both clinical studies, which will clarify the role of GA for diagnosing and monitoring diabetes, and will encourage the introduction of GA in clinical practice.

Emergency department triage of patients with acute chest pain: definition of cardiac troponin I decisional value to manage patients without electrocardiographic evidence of ischemia

2004 ◽  
Vol 42 (5) ◽  
Author(s):  
Pascale Beyne ◽  
Erik Bouvier ◽  
Patrick Werner ◽  
Pierre Bourgoin ◽  
Damien Logeart ◽  
...  
Keyword(s):  
Chest Pain ◽  
Cardiac Troponin ◽  
Troponin I ◽  
Acute Chest Pain ◽  
Final Diagnosis ◽  
Cardiac Troponin I ◽  
Reference Limit ◽  
Coronary Syndrome ◽  
Definition Of ◽  
Upper Reference Limit

AbstractThe aim of this study was to define the use of a new cardiac troponin I (cTnI) assay for emergency patients with chest pain and no specific electrocardiographic changes consistent with the presence of ischemia. Patients (n=106) admitted in Emergency/Cardiology Departments for chest pain and suspicion of acute coronary syndrome (ACS) were randomized into two diagnosis groups (ACS or non-ACS) by two independent cardiologists. cTnI measurements were performed at admission, and 6 hours and 12 hours later with a new generation assay (Access AccuTnI, Beckman Coulter). Using an upper reference limit of 0.04 μg/l, 27 patients had a cTnI elevation not related to the final diagnosis of ischemia; the positive predictive value (PPV) was 67% with specificity 48%. The decisional value was re-defined and set at 0.16 μg/l, a concentration corresponding to the 99th percentile of the non-ACS patient group. Precision (coefficient of variation) was 8% at this level, PPV 97% and specificity 98%. This new decisional value is now used in our institution and could be included in standard care guidelines to improve the management of patients presenting chest pain in emergency departments.

The universal definition of myocardial infarction

2015 ◽  
Author(s):  
Kristian Thygesen ◽  
Joseph S Alpert ◽  
Allan S Jaffe ◽  
Harvey D White
Keyword(s):  
Myocardial Infarction ◽  
Wall Motion ◽  
Regional Wall Motion ◽  
Cardiac Biomarkers ◽  
Regional Wall ◽  
Reference Limit ◽  
Electrocardiographic Changes ◽  
Universal Definition ◽  
Definition Of ◽  
Upper Reference Limit

Myocardial infarction is defined pathologically as myocyte necrosis due to prolonged ischaemia. These conditions are met when there is a detection of a rise and/or fall of cardiac biomarkers, preferably troponins, with at least one value above the 99th percentile of the upper reference limit, together with evidence of myocardial ischaemia, as recognized by at least one of the following: symptoms of ischaemia, electrocardiographic changes of new ischaemia, the development of pathological Q waves, imaging evidence of a new loss of viable myocardium or new regional wall motion abnormality, or the identification of an intracoronary thrombus by angiography or autopsy.

scholarly journals Cerebrospinal Fluid Protein Concentration in Japanese Healthy Older Volunteers

2021 ◽  
Author(s):  
Tatsuya Yoshihara ◽  
Masayoshi Zaitsu ◽  
Kazuya Ito ◽  
Ryuzo Hanada ◽  
Eunhee Chung ◽  
...  
Keyword(s):  
Cerebrospinal Fluid ◽  
Protein Concentration ◽  
Reference Range ◽  
Asian Population ◽  
Reference Limit ◽  
Older Volunteers ◽  
The Mean ◽  
Upper Reference Limit ◽  
Age Range ◽  
Cerebrospinal Fluid Protein

The concentration of cerebrospinal fluid total protein (CSF-TP) is important for the diagnosis of neurological emergencies. Recently, some Western studies have shown that the current upper reference limit of CSF-TP is quite low for older patients. However, little is reported about the concentration of CSF-TP in older Asian population. In this study, we retrospectively analyzed the CSF-TP concentrations in Japanese healthy older volunteers. CSF samples in 69 healthy Japanese volunteers (age range: 55–73 years) were collected by lumbar puncture, and the data of CSF were retrospectively analyzed. The mean (standard deviation) CSF-TP was 41.7 (12.3) mg/dL. The older group (≥ 65 years old) had higher CSF-TP concentration than the younger group (55–64 years old). The 2.5th percentile and 97.5th percentile of CSF-TP were estimated as 22.5 and 73.2 mg/dL, respectively, which were higher than the current reference range in Japan (10–40 mg/dL).

Albumin and calcium reference interval using healthy individuals and a data-mining approach

2020 ◽  
Vol 57 (5) ◽  
pp. 373-381 ◽  
Author(s):  
N Jassam ◽  
A Luvai ◽  
D Narayanan ◽  
D Turnock ◽  
G Lee ◽  
...  
Keyword(s):  
Metrological Traceability ◽  
Reference Interval ◽  
Reference Population ◽  
Reference Intervals ◽  
Healthy Individuals ◽  
Reference Limit ◽  
Common Reference ◽  
Age Related ◽  
Upper Reference Limit ◽  
Analytical Platforms

Background Harmonization of reference intervals for analytes that have a sound calibration and metrological traceability is a widely recommended practice. The UK Pathology Harmony has recently harmonized reference intervals for calcium and albumin. In this study, we have determined the reference intervals for calcium and albumin on the UK’s most commonly used analytical platforms. Method A prospective reference population of healthy individuals was recruited according to the IFCC CRIDL criteria. A second indirect population was collected from 14 primary care setting and measured in laboratories using various analytical platforms and methods (Roche, Abbott, Beckman and Siemens analytical platforms). Results In total, 299 subjects were recruited; the central 95th centile values for calcium for three out of four analytical platforms were in a close agreement with UK Pathology Harmony reference intervals of 2.2–2.6 mmol/L. Reference intervals of BCG methods from both cohorts and irrespective of analytical platforms were higher for both lower and upper reference limits than those for BCP. In comparison, the indirect study showed an age-related variation. The younger population reference intervals varied by up to 5.7% at the lower reference limit and up to 12% at the upper reference limit compared with Pathology Harmony reference intervals, and the older population showed a variation of up to 14% at both limits. Conclusion While calcium reference intervals can be a subject for harmonization, albumin reference intervals studied showed large variation which is unsupportive of embracing a common reference interval for albumin.

scholarly journals The 99th percentile of reference population for cTnI and cTnT assay: methodology, pathophysiology and clinical implications

2017 ◽  
Vol 55 (11) ◽  
Author(s):  
Aldo Clerico ◽  
Martina Zaninotto ◽  
Andrea Ripoli ◽  
Silvia Masotti ◽  
Concetta Prontera ◽  
...  
Keyword(s):  
Task Force ◽  
Clinical Decision ◽  
Reference Population ◽  
Clinical Implications ◽  
Factors Affecting ◽  
Reference Limit ◽  
Physiological Variables ◽  
Mathematical Algorithms ◽  
Regulatory Bodies ◽  
Upper Reference Limit

AbstractAccording to recent international guidelines, including the 2012 Third Universal Definiton of Myocardial Infarction by the Joint ESC/ACCF/AHA/WHF Task Force, an increase in cardiac troponin (cTn) levels over the 99th percentile upper reference limit (99th URL) should be considered clinically relevant, this cut-off being measured with an imprecision ≤10 CV%. In theory 99th URL values strongly depend not only on demographic and physiological variables (i.e. criteria for considering the reference population “healthy”), but also on the analytical performance of cTn methods and mathematical algorithms used for the calculation. The aim of the present article was therefore to review the methodological and pathophysiological factors affecting the evaluation and calculation of the 99th URL for cTn assay. The critical analysis made showed that no uniform procedure is followed, and nor have experts or regulatory bodies provided uniform guidelines for researchers or cTn assays manufacturers as an aid in “their quest to define normality”. In particular, little attention has been paid to the way in which a healthy reference population is to be selected, or the criteria for calculating the 99th URL value for cTn assays, thus highlighting the need for international recommendations not only for demographic and physiological variables criteria for defining a healthy reference population, but also for calculating mathematical algorithms for establishing/calculating clinical decision values. An expert consensus group, comprising laboratory and clinical scientists, biomedical statisticians, industrial and regulatory representatives, should be responsible for drawing up these guidelines.

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