Abstract:
BACKGROUND:For nearly 20 years, we and others have used a three-parameter power function as a direct estimation error model for immunoassays. The main application is imprecision profile plots (after translating from variance to coefficient of variation) but other uses include weighting functions for regression analysis and variance stabilizing transformations. Although generally successful, the intrinsic monotonicity of the function means that it fails to describe small but distinct increases in variance that occasionally occur near the assay detection limit. METHODS:A systematic comparison of five variance functions was undertaken, using randomly drawn samples from a large body of real immunoassay data. RESULTS:Variance function accuracy (hence imprecision profile accuracy) can be markedly improved, particularly near the assay detection limit, by employing a pair of complementary three-parameter power functions, together with a constrained four-parameter function, which provides for a variance turning point. CONCLUSIONS:A set of rules, based on an objective goodness-of-fit statistic, can be used to automate presentation of the most appropriate function for any particular data-set. Flexibility is easily incorporated into the selection rules and is actually highly desirable to encourage ongoing evaluation with a wider variety of data. A Win32 computer program that performs the variance function estimation and plotting is freely available.
journal_name
Ann Clin Biochemjournal_title
Annals of clinical biochemistryauthors
Sadler WAdoi
10.1258/acb.2008.007230subject
Has Abstractpub_date
2008-09-01 00:00:00pages
481-5issue
Pt 5eissn
0004-5632issn
1758-1001pii
45/5/481journal_volume
45pub_type
杂志文章abstract:BACKGROUND:We evaluated the recently released chemiluminescence assay for 25-hydroxy vitamin D (25-OHD) on the Immunodiagnostic Systems iSYS (IDS-iSYS) automated analyser. METHODS:The IDS-iSYS comparison was performed using patient samples previously measured for 25-OHD by a validated liquid chromatography-tandem mass...
journal_title:Annals of clinical biochemistry
pub_type: 杂志文章
doi:10.1258/acb.2011.011018
更新日期:2012-03-01 00:00:00
abstract::Measurement of genetically altered DNA shed from tumours into the circulation can potentially provide a new generation of blood-based cancer biomarkers. Compared with tissue DNA biomarkers which require surgery or biopsy, samples for circulating tumour DNA assays can be obtained with minimal inconvenience and at lower...
journal_title:Annals of clinical biochemistry
pub_type: 杂志文章,评审
doi:10.1177/0004563218798401
更新日期:2019-01-01 00:00:00
abstract::It is our aim to summarise and discuss procedures for the evaluation of the concentration of free ionised calcium in serum or plasma. Stress is laid upon the interrelations and relative validity of the most common algebraic expressions to appraise the calcium status. The multitude of formulae proposed in the literatur...
journal_title:Annals of clinical biochemistry
pub_type: 杂志文章,评审
doi:10.1177/000456328402100501
更新日期:1984-09-01 00:00:00
abstract::Three sensitive assays (Behring, Organon and LKB-Pharmacia) for measurement of serum thyrotropin (TSH) were evaluated. All three assays showed good precision, sensitivity, linearity and for practical purposes negligible high dose hook effects. The correlations between the assays were excellent, but due to standardisat...
journal_title:Annals of clinical biochemistry
pub_type: 杂志文章
doi:10.1177/000456328902600609
更新日期:1989-11-01 00:00:00
abstract::A p-iodophenol-enhanced luminescent end-point has been incorporated into a commercially available heterogeneous competitive enzyme immunoassay for digoxin based on a horseradish peroxidase-digoxin conjugate. The luminescent end-point could be completed in less than 1 min and significantly reduced overall assay time. R...
journal_title:Annals of clinical biochemistry
pub_type: 杂志文章
doi:10.1177/000456328602300104
更新日期:1986-01-01 00:00:00
abstract::Salivary theophylline concentrations in neonates were measured by a homogeneous enzyme immunoassay and compared with serum concentrations. Free serum theophylline concentrations were also compared with salivary concentrations and the values obtained were almost identical. Results using the immunoassay agreed well with...
journal_title:Annals of clinical biochemistry
pub_type: 杂志文章
doi:10.1177/000456329403100311
更新日期:1994-05-01 00:00:00
abstract:BACKGROUND:Calculated globulin fraction is derived from the liver function tests by subtracting albumin from the total protein. Since immunoglobulins comprise the largest component of the serum globulin concentration, increased or decreased calculated globulins and may identify patients with hypogammaglobulinaemia or h...
journal_title:Annals of clinical biochemistry
pub_type: 杂志文章
doi:10.1177/0004563221989737
更新日期:2021-01-11 00:00:00
abstract::Background Accumulating evidence shows an over-abundance of Fusobacterium nucleatum in colorectal tumour tissues. Although stool DNA testing of Fusobacterium nucleatum might be a potential marker for the detection of colorectal tumours, the difficulty in detecting Fusobacterium nucleatum in stool by conventional metho...
journal_title:Annals of clinical biochemistry
pub_type: 杂志文章
doi:10.1177/0004563216643970
更新日期:2017-01-01 00:00:00
abstract::Plasma immunoreactive alpha-atrial natriuretic peptide (IR alpha-ANP) levels were determined before, and at 5 and 10 min after bolus intravenous administration of morphine (0.15 or 0.30 mg/kg) in 21 otherwise healthy human subjects who underwent elective surgery. Five min after injection IR alpha-ANP levels had nearly...
journal_title:Annals of clinical biochemistry
pub_type: 杂志文章
doi:10.1177/000456329002700105
更新日期:1990-01-01 00:00:00
abstract::Haptoglobin is an acute-phase protein with three major phenotypes: Hp 1-1, Hp 2-1 and Hp 2-2. Studies have shown that functional differences between these phenotypes have important consequences in a number of pathological disorders (e.g. cardiovascular disease, autoimmune disorders, infectious disease), making phenoty...
journal_title:Annals of clinical biochemistry
pub_type: 杂志文章
doi:10.1177/000456329903600507
更新日期:1999-09-01 00:00:00
abstract::The diagnostic usefulness of fasting total serum bile acids (SBA/F) in the detection of liver diseases and assessment of different aspects of hepatic function alteration was evaluated in 61 healthy subjects and 186 patients with liver disease. The value of SBA/F was compared with other routine tests. In 49 healthy sub...
journal_title:Annals of clinical biochemistry
pub_type: 杂志文章
doi:10.1177/000456328502200608
更新日期:1985-11-01 00:00:00
abstract:INTRODUCTION:Plantain, a herbal remedy, has been reported to interfere with therapeutic drug monitoring of digoxin. We evaluated three commercially available plantain products for potential interference with therapeutic drug monitoring of digoxin and 13 other common drugs. METHOD:Dry content of plantain capsule or pla...
journal_title:Annals of clinical biochemistry
pub_type: 杂志文章
doi:10.1258/000456306776865214
更新日期:2006-05-01 00:00:00
abstract::An evaluation of the Amerlex system for determination of total thyroxine (T4) and total triiodothyronine (T3) is described. The within- and between-batch precisions were acceptable, and analyses of quality control material and linearity studies demonstrated good accuracy at the clinical decision levels. The correlatio...
journal_title:Annals of clinical biochemistry
pub_type: 杂志文章
doi:10.1177/000456328201900208
更新日期:1982-03-01 00:00:00
abstract::A study of conditions for the elution of apo A1 and B lipoproteins from dried blood spots has led to the development of an apo B/A1 ratio assay with results for dried blood spots which are comparable with serum assays. This assay has been developed to be suitable for large scale population screening. The concept of me...
journal_title:Annals of clinical biochemistry
pub_type: 杂志文章
doi:10.1177/000456329303000511
更新日期:1993-09-01 00:00:00
abstract::The application of a DC plasma emission spectrometer to the measurement of copper, zinc and magnesium in serum and urine is reported. Each assay requires only a simple dilution in 1% nitric acid. Comparisons with standard atomic absorption techniques showed good analytical agreement, especially for copper and magnesiu...
journal_title:Annals of clinical biochemistry
pub_type: 杂志文章
doi:10.1177/000456328502200512
更新日期:1985-09-01 00:00:00
abstract:BACKGROUND:In the enzyme reaction for the determination of the unbound (free) bilirubin concentration by glucose oxidase and peroxidase, materials with low affinity for serum protein are reactive. The influence of these materials on the determination of serum unbound bilirubin was investigated. METHODS Serum samples fr...
journal_title:Annals of clinical biochemistry
pub_type: 杂志文章
doi:10.1177/000456320203900606
更新日期:2002-11-01 00:00:00
abstract::We describe a new electrochemical method for the determination of erythrocyte acetylcholinesterase activity (EC 3.1.1.7) and plasma cholinesterase (EC 3.1.1.8) activity, based on the measurements of pH variation due to release of acetic acid from acetylcholine. The major advantages of the differential pH procedure are...
journal_title:Annals of clinical biochemistry
pub_type: 杂志文章
doi:10.1177/000456328602300509
更新日期:1986-09-01 00:00:00
abstract::We examined the reactivity of human serum albumin-bound bilirubin and its photoisomers as substrates for a direct bilirubin assay using bilirubin oxidase. The reduction of (EZ)-cyclobilirubin reached 100% 5 min after addition of the enzyme at any pH tested (3.5-7.4) in 0.1 mol/L phosphate buffer, whereas the reduction...
journal_title:Annals of clinical biochemistry
pub_type: 杂志文章
doi:10.1177/000456320003700404
更新日期:2000-07-01 00:00:00
abstract:BACKGROUND:Serum ornithine carbamoyltransferase is a diagnostic marker of hepatic disorders due to its localization in periportal mitochondria. METHODS:We have developed a new method for the determination of serum ornithine carbamoyltransferase. It is based on the reverse reaction of ornithine carbamoyltransferase, us...
journal_title:Annals of clinical biochemistry
pub_type: 杂志文章
doi:10.1258/000456303321610583
更新日期:2003-05-01 00:00:00
abstract::We present two cases of spuriously high cerebrospinal fluid glucose concentration with approximately normal blood glucose concentrations. The cause of these abnormal findings was the use of inappropriate collection tubes during the pre-analytical phase. Whilst no patient harm was identified following this error, signi...
journal_title:Annals of clinical biochemistry
pub_type: 杂志文章
doi:10.1177/0004563214547284
更新日期:2015-01-01 00:00:00
abstract:BACKGROUND:As lifespan in HIV infection increases, cardiovascular disease has emerged as a cause of morbidity and mortality. Asymmetric dimethylarginine is an established marker of endothelial dysfunction and predicts cardiovascular events. The role of asymmetric dimethylarginine in HIV-related cardiovascular disease h...
journal_title:Annals of clinical biochemistry
pub_type: 杂志文章
doi:10.1177/0004563213505848
更新日期:2014-09-01 00:00:00
abstract::The deproteinised sample (150 microliters) is 'injected' into a continuously flowing stream of deionised water which is pumped, via a capillary tube, to the nebuliser of an atomic absorption spectrophotometer. Analytical readout is obtained, in the form of transient peaks, 6 s after sample injection. Before injection ...
journal_title:Annals of clinical biochemistry
pub_type: 杂志文章
doi:10.1177/000456328302000202
更新日期:1983-03-01 00:00:00
abstract::Serum concentrations of total thyroid hormones, thyroid hormone binding proteins, free thyroid hormones and thyroid stimulating hormone (TSH) were measured in a large group of healthy normal subjects (n = 218) to determine the influence of age and sex on tests of thyroid function. No effect of age on measurements of t...
journal_title:Annals of clinical biochemistry
pub_type: 杂志文章
doi:10.1177/000456328502200506
更新日期:1985-09-01 00:00:00
abstract:BACKGROUND:Patients with mutations of succinate dehydrogenase B (SDHB) and succinate dehydrogenase D (SDHD) are at high risk of paraganglioma necessitating surveillance. Chromogranin A has been proposed as a biochemical marker of paraganglioma. We sought to determine the diagnostic utility of chromogranin A in a popula...
journal_title:Annals of clinical biochemistry
pub_type: 杂志文章
doi:10.1177/0004563218811865
更新日期:2019-01-01 00:00:00
abstract::Most UK clinical laboratories use alkaline phosphatase (ALP) methods similar to that proposed by the International Federation of Clinical Chemistry (IFCC), based on the use of 2-amino-2-methyl-1-propanol (AMP) buffer. We present evidence of significant differences in results produced by apparently similar commercial A...
journal_title:Annals of clinical biochemistry
pub_type: 杂志文章
doi:10.1177/000456329803500117
更新日期:1998-01-01 00:00:00
abstract::Serum total sialic acid (TSA) has gained medical interest, particularly as a cardiovascular risk factor and it has been hypothesized that serum levels relate to serum acute phase proteins, some of which are sialylated. We assayed serum TSA and also lipid associated sialic acid (LASA) in 50 normal individuals (24 male)...
journal_title:Annals of clinical biochemistry
pub_type: 杂志文章
doi:10.1177/000456329303000406
更新日期:1993-07-01 00:00:00
abstract:BACKGROUND:Hypercholesterolemia (plasma cholesterol concentration â¥5.2 mmol/L) is a risk factor for cardiovascular disease and stroke. Many different cholesterol self-tests are readily available at general stores, pharmacies and web shops. However, there is limited information on their analytical and diagnostic perfor...
journal_title:Annals of clinical biochemistry
pub_type: 杂志文章
doi:10.1177/0004563221992393
更新日期:2021-01-21 00:00:00
abstract::Measurement of urinary free cortisol using the Bayer Automated Chemiluminescent System (ACS:180 PLUS) was evaluated and compared with an in-house extraction radioimmunoassay (RIA). Inter-assay coefficients of variation were acceptable, being respectively 5.3%, 4.8% and 3.8% at 141, 406 and 942 nmol/L (n=20) for the AC...
journal_title:Annals of clinical biochemistry
pub_type: 杂志文章
doi:10.1177/000456320003700414
更新日期:2000-07-01 00:00:00
abstract::Heterophilic antibodies are well described, but poorly appreciated interferents and is often not a recognized problem affecting most immunoassays. We report a patient presented with ectopic Cushing's syndrome (CS), but repeated plasma adrenocorticotropic hormone (ACTH) concentrations conducted by immunoassay were inap...
journal_title:Annals of clinical biochemistry
pub_type: 杂志文章
doi:10.1177/0004563214520751
更新日期:2014-07-01 00:00:00
abstract::Experience in the use of an in-house urinary free catecholamine assay for the investigation of possible neural crest tumours in a District General Hospital laboratory is described. Elevated excretion of catecholamines and vanillylmandelic acid was found in a number of cases including phaeochromocytoma and neuroblastom...
journal_title:Annals of clinical biochemistry
pub_type: 杂志文章
doi:10.1177/000456328702400512
更新日期:1987-09-01 00:00:00