Abstract:
BACKGROUND:A crucial question when developing reference intervals is whether different subpopulations need their own reference interval or if a single joint reference interval can be used. It is reasonable to use partitioned reference intervals in situations where a single interval results in considerable variation in sensitivity between subpopulations. The aim of partitioning is to harmonize the sensitivity of the reference intervals, i.e., to make the sensitivity similar for all patients, regardless of patient characteristics. Statistical criteria to identify when partitioning is adequate have been developed over the last two decades. These criteria are applicable when considering two subpopulations, but recently a procedure for considering several subpopulations has been developed. When several subpopulations are considered, there is a possibility that some subpopulations could form a group or cluster that could share a common reference interval. However, there is no formal systematic approach to indicate how to divide these subpopulations into clusters. The aim of this study was to suggest such a systematic approach for clustering. METHODS:A clustering technique was applied to data including several subpopulations. The technique is based on measuring the distance between separated reference limits and successively pooling subpopulations divided by short distances. A cluster is defined by a group of subpopulations that are close to each other and that differ from subpopulations in another cluster. A cluster recruits new subpopulations as long as the subpopulations can be pooled without violating a partitioning criterion. CONCLUSIONS:We have suggested a procedure for partitioning a number of Gaussian (or Gaussian-transformable) subpopulations into clusters. This is the only formalized procedure indicating how to analyze several subpopulations and identify a suitable number of groups and reference intervals. Using a computer program developed for partitioning issues, the approach was easy to adopt.
journal_name
Clin Chem Lab Medjournal_title
Clinical chemistry and laboratory medicineauthors
Gellerstedt M,Petersen PHdoi
10.1515/CCLM.2007.192subject
Has Abstractpub_date
2007-01-01 00:00:00pages
1026-32issue
8eissn
1434-6621issn
1437-4331journal_volume
45pub_type
杂志文章abstract::Until recently, the "human genome" programs were mainly directed towards the development of maps to identify disease genes. The genetic map comprises about 8000 highly informative second generation markers of the microsatellite type. The density of markers is now sufficient to localize a gene for a monogenic disease w...
journal_title:Clinical chemistry and laboratory medicine
pub_type: 杂志文章
doi:10.1515/CCLM.1998.086
更新日期:1998-08-01 00:00:00
abstract:BACKGROUND:There are several methods for calculating serum osmolality, and their accordance with measured osmolality is the subject of controversy. METHODS:The concentrations of sodium, potassium, glucose, blood urea nitrogen (BUN) and osmolalities of 210 serum samples were measured. Two empirical equations were deduc...
journal_title:Clinical chemistry and laboratory medicine
pub_type: 杂志文章
doi:10.1515/CCLM.2005.109
更新日期:2005-01-01 00:00:00
abstract:BACKGROUND:The presence of preanalytical mistakes (PM) in samples from primary care centres (PCC) is a widely studied topic. Different correcting strategies have been proposed, with variable success. We planned a series of multidisciplinary sessions for clinical update, with the aim to decrease PM rates in samples from...
journal_title:Clinical chemistry and laboratory medicine
pub_type: 杂志文章
doi:10.1515/cclm-2016-1002
更新日期:2017-10-26 00:00:00
abstract:BACKGROUND:Lysosphingolipids (LysoSLs) are derivatives of sphingolipids which have lost the amide-linked acyl chain. More recently, LysoSLs have been identified as storage compounds in several sphingolipidoses, including Gaucher, Fabry and Niemann-Pick diseases. To date, different methods have been developed to measure...
journal_title:Clinical chemistry and laboratory medicine
pub_type: 杂志文章
doi:10.1515/cclm-2016-0340
更新日期:2017-03-01 00:00:00
abstract:BACKGROUND:Decreased brain-derived neurotrophic factor (BDNF) has been demonstrated in animal models and patients with depression. However, little is known about changes in BDNF in post-stroke depression (PSD). This study investigated the changes in serum BDNF in patients with PSD, and evaluated whether serum concentra...
journal_title:Clinical chemistry and laboratory medicine
pub_type: 杂志文章
doi:10.1515/CCLM.2011.039
更新日期:2011-02-01 00:00:00
abstract::Despite many years of study, clinical trials of new drugs to prevent thrombosis have often been disappointing. Part of the problem lies in our incomplete understanding of the regulation of plasminogen activation and/or inhibition in vivo. We have previously shown that in vitro nitration of plasminogen in plasma by per...
journal_title:Clinical chemistry and laboratory medicine
pub_type: 杂志文章
doi:10.1515/CCLM.2006.039
更新日期:2006-01-01 00:00:00
abstract::A rat model is introduced which enables investigations in anticoagulated blood with continuous measurements by a flow-through electrode system. In the present study, a potentiometric ion-selective electrode (ISE)-system was used for measuring Ca2+, K+, Na+ and pH in rats. The setup was adjusted to an extracorporeal bl...
journal_title:Clinical chemistry and laboratory medicine
pub_type: 杂志文章
doi:10.1515/CCLM.1998.149
更新日期:1998-11-01 00:00:00
abstract:UNLABELLED:The pathogenesis of abdominal aortic aneurysms (AAA) is a complex process in which atherosclerosis and inflammation play a leading role. Cytokines are important mediators of both processes. The aim of our study was to determine whether plasma levels of cytokines which are most involved in AAA pathogenesis ca...
journal_title:Clinical chemistry and laboratory medicine
pub_type: 杂志文章
doi:10.1515/CCLM.2000.178
更新日期:2000-11-01 00:00:00
abstract::The importance of nutrition factors such as calcium, vitamin D and vitamin K for the integrity of the skeleton is well known. Moreover, bone health is positively influenced by certain elements (e.g., zinc, copper, fluorine, manganese, magnesium, iron and boron). Deficiency of these elements slows down the increase of ...
journal_title:Clinical chemistry and laboratory medicine
pub_type: 杂志文章,评审
doi:10.1515/cclm-2012-0868
更新日期:2013-08-01 00:00:00
abstract:BACKGROUND:The aim of our study was to determine the frequency of anti-thyroid-stimulating hormone (TSH) receptor antibodies (TRAb) in Tunisian patients with Graves' disease (GD) and to compare the validity of TRAb to that of thyroperoxidase (TPO-Ab) and thyroglobulin antibodies (TG-Ab). METHODS:ELISA was used to dete...
journal_title:Clinical chemistry and laboratory medicine
pub_type: 杂志文章
doi:10.1515/CCLM.2007.016
更新日期:2007-01-01 00:00:00
abstract:BACKGROUND:Autoantibodies against β1-adrenergic receptors (β1AR) that stimulate cardiac cAMP-production play a causal role in the pathogenesis of human heart failure. Patients can be subjected to specific therapies, if the presence of potentially cardio-noxious β1AR-autoantibodies is reliably diagnosed. This requires a...
journal_title:Clinical chemistry and laboratory medicine
pub_type: 杂志文章
doi:10.1515/cclm-2015-0603
更新日期:2016-04-01 00:00:00
abstract:BACKGROUND:External quality assessment/proficiency test (EQA/PT) organizers play an important role in monitoring the performance of HbA1c measurements. With increasing quality of the assays, HbA1c is increasingly used for diagnosis of diabetes and the demands on EQA/PT organizers themselves are rising constantly. EQA o...
journal_title:Clinical chemistry and laboratory medicine
pub_type: 杂志文章
doi:10.1515/cclm-2016-0123
更新日期:2016-11-01 00:00:00
abstract:BACKGROUND:Automated systems have been broadly used in the counting of particles in urine, while manual microscopic analyses are still required for confirming components of urine sediments, especially pathologic casts and other unknown particles. Good review rules can reduce the number of manual urine microscopy examin...
journal_title:Clinical chemistry and laboratory medicine
pub_type: 杂志文章
doi:10.1515/cclm-2012-0272
更新日期:2012-12-01 00:00:00
abstract:BACKGROUND:The compatibility of immunoassay tests in different sample matrices is extremely important during the assay validation process. In this study, we investigated the interchangeability of some Access (and therefore all the UniCel Family platforms) assays between serum and plasma. METHODS:We tested approximatel...
journal_title:Clinical chemistry and laboratory medicine
pub_type: 杂志文章
doi:10.1515/CCLM.2008.032
更新日期:2008-01-01 00:00:00
abstract:BACKGROUND:Tests for fecal calprotectin are usually either enzyme-linked immunosorbent assays (ELISA) or a time-resolved fluorimetric immunoassay (TRFIA). These time-consuming tests are performed only once every 1 or 2 weeks. Before the results of the tests are known most patients have already undergone colonoscopy. A ...
journal_title:Clinical chemistry and laboratory medicine
pub_type: 杂志文章
doi:10.1515/cclm-2011-0855
更新日期:2012-01-13 00:00:00
abstract:BACKGROUND:Sequencing based mutation screening assays of genes encompassing large numbers of exons could be substantially optimized by multiplex PCR, which enables simultaneous amplification of many targets in one reaction. In the present study, a multiplex PCR protocol originally developed for fragment analysis was ev...
journal_title:Clinical chemistry and laboratory medicine
pub_type: 杂志文章
doi:10.1515/CCLM.2009.012
更新日期:2009-01-01 00:00:00
abstract:BACKGROUND:Potassium is an important serum ion that is frequently assayed in clinical laboratories. Quality assurance requires reference methods; thus, the establishment of a candidate reference method for serum potassium measurements is important. METHODS:An inductively coupled plasma mass spectrometry (ICP-MS) metho...
journal_title:Clinical chemistry and laboratory medicine
pub_type: 杂志文章
doi:10.1515/cclm-2016-0803
更新日期:2017-08-28 00:00:00
abstract::Hyperhomocysteinemia (HHcy) is a significant and independent risk factor for cardiovascular disease (CVD) and the underlying mechanism is unclear. We and others have reported that homocysteine (Hcy) is inversely correlated with plasma high-density lipoprotein cholesterol (HDL-C) and apolipoprotein AI (apoA-I) in patie...
journal_title:Clinical chemistry and laboratory medicine
pub_type: 杂志文章,评审
doi:10.1515/CCLM.2007.358
更新日期:2007-01-01 00:00:00
abstract:BACKGROUND:There is a need for reference materials (RMs) in the field of genetic testing for verification of test results obtained in patients and probands. For the frequent genetic variation G20210A in the prothrombin gene, it has been shown that purified plasmids containing the gene fragment harbouring the mutation c...
journal_title:Clinical chemistry and laboratory medicine
pub_type: 杂志文章
doi:10.1515/CCLM.2008.093
更新日期:2008-01-01 00:00:00
abstract:BACKGROUND:Plasma iron is increased in preeclampsia (PE) when compared to healthy pregnant women. This is in contrast to inflammation characteristic for PE. The link between iron homeostasis and inflammation is hepcidin. Our goal was to describe hepcidin concentrations and its association with iron homeostasis in PE. ...
journal_title:Clinical chemistry and laboratory medicine
pub_type: 杂志文章
doi:10.1515/CCLM.2010.290
更新日期:2010-10-01 00:00:00
abstract::Reference intervals in clinical chemistry are commonly based on results of measurements in reference populations or are taken from the literature. A reference population should represent a defined group of individuals and be as similar as possible to the patients under investigation. Frequently, reference populations ...
journal_title:Clinical chemistry and laboratory medicine
pub_type: 杂志文章
doi:10.1515/CCLM.2000.093
更新日期:2000-07-01 00:00:00
abstract:BACKGROUND:Knowledge of the fatty acid composition of lipid classes in human plasma is an important factor in the investigation of human metabolism. Therefore, a method for the analysis of neutral lipid (NL), phospholipid (PL) and free fatty acids (FFA) in human plasma has been developed and validated. METHODS:Separat...
journal_title:Clinical chemistry and laboratory medicine
pub_type: 杂志文章
doi:10.1515/cclm-2012-0203
更新日期:2013-04-01 00:00:00
abstract:BACKGROUND:When performed erroneously, the venous blood specimen collection (VBSC) practice steps patient identification, test request management and test tube labeling are at high risk to jeopardize patient safety. VBSC educational programs with the intention to minimize risk of harm to patients are therefore needed. ...
journal_title:Clinical chemistry and laboratory medicine
pub_type: 杂志文章
doi:10.1515/cclm-2018-0051
更新日期:2018-10-25 00:00:00
abstract:BACKGROUND:Antinuclear autoantibody determination relies on an initial screening step using immunofluorescence on HEp2 cells. This may be followed by anti-deoxyribonucleic acid (DNA) determination, if the fluorescence of nuclei is homogeneous. We assessed the validity of a restricted algorithm and compared this to a mo...
journal_title:Clinical chemistry and laboratory medicine
pub_type: 杂志文章
doi:10.1515/CCLM.2009.122
更新日期:2009-01-01 00:00:00
abstract::ISO 15189's particular requirements for quality management in medical laboratories provide guidance for (a) relating performance specifications to the intended use of a test or examination procedure, (b) designing internal quality control (IQC) procedures to verify the attainment of the intended quality of test result...
journal_title:Clinical chemistry and laboratory medicine
pub_type: 杂志文章
doi:10.1515/CCLM.2010.024
更新日期:2010-01-01 00:00:00
abstract::It is not clear whether brain natriuretic peptide (BNP) or N-terminal proBNP (NT-proBNP) is superior as a diagnostic and prognostic indicator in cardiac diseases. Here, we compare the clinical correlations of both peptides in a population of 92 ambulatory patients with heart failure, using a well-established immunorad...
journal_title:Clinical chemistry and laboratory medicine
pub_type: 杂志文章
doi:10.1515/CCLM.2002.130
更新日期:2002-08-01 00:00:00
abstract:BACKGROUND:Heparin is the standard drug for anticoagulation treatment and is used in many cardiac surgical interventions to prevent blood clotting. The anticoagulation status is controlled by various clotting tests. However, these tests depend on parameters like temperature, hemodilution etc. and are thus not applicabl...
journal_title:Clinical chemistry and laboratory medicine
pub_type: 杂志文章
doi:10.1515/cclm-2013-0278
更新日期:2013-10-01 00:00:00
abstract::We report on the performance of a new test, holotranscobalamin, as compared to well established markers of vitamin B12 deficiency (plasma cobalamins, methylmalonic acid, and homocysteine). Holotranscobalamin was analyzed in 143 samples by a competitive radiobinding assay (Axis-Shield). Employing a cut-off value of 50 ...
journal_title:Clinical chemistry and laboratory medicine
pub_type: 杂志文章
doi:10.1515/CCLM.2003.228
更新日期:2003-11-01 00:00:00
abstract:BACKGROUND:Malaria infection with Plasmodium falciparum is an important basic health problem in the tropical and sub-tropical countries. The standard diagnostic method is blood film examination to visualize parasite morphology. However, in cases of low parasitemia or mixed infection with very low cryptic species, micro...
journal_title:Clinical chemistry and laboratory medicine
pub_type: 杂志文章
doi:10.1515/CCLM.2011.178
更新日期:2011-08-01 00:00:00
abstract:BACKGROUND:Mid-regional pro-adrenomedullin (MR-proADM) and endothelin-1 have been shown to predict mortality of patients with acute myocardial infarction. However, the prognostic value of both biomarkers in predicting long-term clinical events after acute myocardial infarction remains unclear. METHODS:In a prospective...
journal_title:Clinical chemistry and laboratory medicine
pub_type: 杂志文章
doi:10.1515/CCLM.2008.040
更新日期:2008-01-01 00:00:00