Abstract：
BACKGROUND:Methylmalonic acid (MMA) in plasma or serum is widely used for assessment of vitamin B(12) status. However, data are sparse regarding factors, besides renal function, that may influence MMA concentrations. We searched for important determinants of plasma MMA in the general population. METHODS:In 6946 middle-aged (47-49 years) and elderly (71-74 years) individuals from the Hordaland Homocysteine Study in Norway, we collected anthropometric measurements, lifestyle data, and plasma MMA, vitamin B(12), and creatinine measurements. For 5820 individuals, we also collected dietary data. RESULTS:Age and plasma creatinine were positively associated with plasma MMA, whereas plasma vitamin B(12) was negatively associated. These variables together with sex were the strongest determinants of plasma MMA, accounting for 16% of the variation (R(2) = 0.16). Addition of anthropometric measures and lifestyle and dietary factors only gave slight improvement (total R(2) = 0.167). Increased plasma MMA was seen when plasma vitamin B(12) was <400 pmol/L. In individuals with vitamin B(12) >or =400 micromol/L (vitamin B(12)-replete), the 2.5th-97.5th percentile reference limits for MMA were 0.10-0.28 micromol/L (middle-aged) and 0.10-0.36 micromol/L (elderly). When plotted against creatinine (nomograms), the 97.5th percentile of MMA was similar in men and women but approximately 0.15 micromol/L higher in elderly than middle-aged individuals. Vitamin B(12)-replete participants had MMA upper limits approximately 0.1 micromol/L (elderly) and 0.04 micromol/L (middle-aged) below those of the unselected population at all creatinine concentrations. CONCLUSIONS:Identified determinants accounted for <17% of the overall variation in plasma MMA. The difference in MMA between middle-aged and elderly individuals is only partly explained by creatinine and vitamin B(12) concentrations.
journal_name
Clin Chemjournal_title
Clinical chemistryauthors
Vogiatzoglou A,Oulhaj A,Smith AD,Nurk E,Drevon CA,Ueland PM,Vollset SE,Tell GS,Refsum Hdoi
10.1373/clinchem.2009.128678subject
Has Abstractpub_date
2009-12-01 00:00:00pages
2198-206issue
12eissn
0009-9147issn
1530-8561pii
clinchem.2009.128678journal_volume
55pub_type
杂志文章abstract：:This procedure for routine quantification of albumin in urine is based on the dye-binding properties of albumin with bromphenol blue. The absorbance of 100 microL of urine mixed with 3 mL of color reagent is measured against blank reagent at 610 nm after 30 s. Results vary linearly with albumin concentration up to 6 g...
journal_title：Clinical chemistry
pub_type： 杂志文章
doi：
更新日期：1987-02-01 00:00:00
abstract：BACKGROUND:Quantification of 5-hydroxyindole-3-acetic acid (5-HIAA) in urine is useful in diagnosing and monitoring of patients with carcinoid tumors and in the study of serotonin (5-hydroxytryptamine) metabolism in various disorders. We describe an automated method that incorporates on-line solid-phase extraction (SPE...
journal_title：Clinical chemistry
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doi：10.1373/clinchem.2005.050062
更新日期：2005-09-01 00:00:00
abstract：:Gene mutations responsible for the majority of Duchenne/Becker muscular dystrophy (DMD/BMD) and cystic fibrosis (CF) chromosomes have been identified. We describe a DNA-based strategy, rather than the traditional biochemical assays, for screening newborns. DNA sequences spanning the CF mutation and several DMD/BMD del...
journal_title：Clinical chemistry
pub_type： 杂志文章
doi：
更新日期：1990-10-01 00:00:00
abstract：BACKGROUND:The coexistence of hypertension and dyslipidemia synergistically increases the risk of cardiovascular events. We investigated the effect of the lipid-lowering agent micronized fenofibrate on inhibition of carotid atherosclerosis in patients with essential hypertension and mild hyperlipidemia. METHODS:We mea...
journal_title：Clinical chemistry
pub_type： 杂志文章,随机对照试验
doi：10.1373/clinchem.2006.074724
更新日期：2006-11-01 00:00:00
abstract：:In this immunoenzymatic assay for human lutropin (hLH) we used bi-specific antibodies (BiAbs) obtained from the fusion of two hybridomas producing antibodies to beta-D-galactosidase and hLh. The BiAb complexed with the enzyme beta-D-galactosidase was used as tracer in a double-determinant assay. We compared the assay ...
journal_title：Clinical chemistry
pub_type： 杂志文章
doi：
更新日期：1990-01-01 00:00:00
abstract：BACKGROUND:Diabetes mellitus has been historically divided into type 1 and type 2 diabetes, with type 1 being an autoimmune disease and type 2 being primarily a metabolic disease. CONTENT:The current diabetes classification scheme needs to be reevaluated because of the accumulating evidence of immune system involvemen...
journal_title：Clinical chemistry
pub_type： 杂志文章,评审
doi：10.1373/clinchem.2010.148270
更新日期：2011-02-01 00:00:00
abstract：:The enzymatic determination of serum uric acid by use of uricase, catalase, and aldehyde dehydrogenase according to Haeckel [J. Clin. Chem. Clin Biochem. 14, 101 (1976)] showed interferences from ethanol-converting enzymes, which are present in some patients' sera. We have identified these enzymes as alcohol dehydroge...
journal_title：Clinical chemistry
pub_type： 杂志文章
doi：
更新日期：1979-04-01 00:00:00
abstract：:A modified gas-liquid chromatographic method for determining plasma concentrations of bupivacaine and lidocaine is described, with cyclizine as an internal standard. The extraction procedure requires no solvent evaporation, thus overcoming the problem of drug volatility. Concentrations as low as 0.1 mg/liter can be de...
journal_title：Clinical chemistry
pub_type： 杂志文章
doi：
更新日期：1978-09-01 00:00:00
abstract：:C-reactive protein (CRP) concentrations were serially determined in serum after kidney or heart transplantation. The initial postsurgical CRP response in these patients was compared with that of control patients undergoing related procedures but not subjected to immunosuppressive therapy. Immunosuppression clearly dep...
journal_title：Clinical chemistry
pub_type： 杂志文章
doi：
更新日期：1986-04-01 00:00:00
abstract：:We describe a chromatographic procedure for sensitive (2.0 mumol/L), specific quantification of vanillylmandelic acid (VMA) in urine with iso-VMA as an internal standard. After rapid extraction from urine, the VMA is determined by isocratic reversed-phase ion-pair chromatography on a bonded C8 column and detection of ...
journal_title：Clinical chemistry
pub_type： 杂志文章
doi：
更新日期：1986-04-01 00:00:00
abstract：:A one-stage semiautomated method for estimating total phospholipids in plasma is reported. The phospholipids are extracted into aqueous ethanol, combined with a Lewis acid, and the change in pH is monitored colorimetrically. The method, compared with the acid digestion method of Gomori [J. Lab. Clin. Med. 27, 955 (194...
journal_title：Clinical chemistry
pub_type： 杂志文章
doi：
更新日期：1977-09-01 00:00:00
abstract：:We examined the relationship in a large-living population between the concentration of triglycerides in plasma from fasting persons and the concentration of very-low-density lipoprotein cholesterol (VLDL-C) as determined after preparative ultracentrifugation. Data from individuals in the Framingham Heart Study who wer...
journal_title：Clinical chemistry
pub_type： 杂志文章
doi：
更新日期：1981-12-01 00:00:00
abstract：BACKGROUND:Mucopolysaccharidosis type II (MPS II) is a lysosomal storage disorder related to a deficiency in the enzyme iduronate-2-sulfatase (IDS). Clinical trials of enzyme replacement therapy are in progress, but effective treatment will require screening assays to enable early detection and diagnosis of MPS II. Our...
journal_title：Clinical chemistry
pub_type： 杂志文章
doi：10.1373/clinchem.2005.061838
更新日期：2006-04-01 00:00:00
abstract：:We used gas chromatography-mass spectrometry to analyze serum specimens from a patient whose metabolic ketoacidosis resulted from sniffing a toluene-containing substance; we also analyzed a sample of the abused substance itself and a serum specimen from a normal subject. The blood samples from the patient showed abnor...
journal_title：Clinical chemistry
pub_type： 杂志文章
doi：
更新日期：1988-12-01 00:00:00
abstract：BACKGROUND:Recent reports have described inherent problems with androgen immunoassays compared with mass spectrometry analyses. METHODS:We developed a method for measuring serum testosterone (T) and 5alpha-dihydrotestosterone (DHT) simultaneously via liquid-liquid extraction followed by liquid chromatography-tandem ma...
journal_title：Clinical chemistry
pub_type： 杂志文章
doi：10.1373/clinchem.2008.103846
更新日期：2008-11-01 00:00:00
abstract：BACKGROUND:Hyperglycosylated human chorionic gonadotropin (hCG-h) contains larger and more complex carbohydrate chains than regular human chorionic gonadotropin (hCG). hCG-h is thought to be the major form of hCG produced by testicular cancers and it has been suggested to play a key role in tumor invasion, but studies ...
journal_title：Clinical chemistry
pub_type： 杂志文章
doi：10.1373/clinchem.2012.183723
更新日期：2012-07-01 00:00:00
abstract：:Two-dimensional electroimmunodiffusion is rarely used in clinical chemistry, because its potentialities are not yet widely appreciated. Studying mouse anaphylaxis, we observed with this technique certain striking short- and long-term pathologic changes in several important serum antigens, which aptly demonstrate its u...
journal_title：Clinical chemistry
pub_type： 杂志文章
doi：
更新日期：1979-05-01 00:00:00
abstract：:We report a simple, enzymatic, end point method for determining nitrate in serum and urine with use of nitrate reductase from Aspergillus sp. (EC 1.6.6.2). The decrease in absorbance at 340 nm as a result of the oxidation of beta-NADPH is measured. We used FAD as a supplementary electron carrier and added an internal ...
journal_title：Clinical chemistry
pub_type： 杂志文章
doi：
更新日期：1995-06-01 00:00:00
abstract：:In iron deficiency, zinc protoporphyrin (ZPP) is produced instead of heme, and the ZPP concentration in erythrocytes is increased (normal < or = 40 mumol/mol heme). We investigated the relevance of ZPP for staging iron deficiency. ZPP was determined by hematofluorometry in samples from 103 patients. Nineteen patients ...
journal_title：Clinical chemistry
pub_type： 杂志文章
doi：
更新日期：1994-05-01 00:00:00
abstract：BACKGROUND:This Case Conference reviews the normal changes in thyroid activity that occur during pregnancy and the proper use of laboratory tests for the diagnosis of thyroid dysfunction in the pregnant patient. CASE:A woman in the 18th week of pregnancy presented with tachycardia, increased blood pressure, severe vom...
journal_title：Clinical chemistry
pub_type： 杂志文章,评审
doi：
更新日期：1999-12-01 00:00:00
abstract：:This article reviews key advances in ion-selective electrode technology that have made potentiometric measurements of ionized calcium (Ca2+) reliable and precise. Our use of two second-generation Ca2+ analyzers (Radiometer ICA1 and NOVA 8) made possible uninterrupted service as volume increased to 31 640 patient tests...
journal_title：Clinical chemistry
pub_type： 杂志文章,评审
doi：
更新日期：1986-08-01 00:00:00
abstract：:A rapid (30-min) semiautomated continuous-flow procedure is described for use in assessing the phospholipids of the particulate ("lamellar body") fraction of human amniotic fluid. The method is based on measuring the difference in fluorescence of 1,6,-diphenyl-1,3,5-hexatriene added to amniotic fluid before and after ...
journal_title：Clinical chemistry
pub_type： 杂志文章
doi：
更新日期：1983-02-01 00:00:00
abstract：BACKGROUND:The bleeding time (BT) test predicts a higher bleeding complication rate in populations at risk for inherited or acquired platelet dysfunction, but it is of limited assistance in evaluating individual patients. There are no reports of clinical outcomes after discontinuation of the BT test. METHODS:Interview...
journal_title：Clinical chemistry
pub_type： 杂志文章
doi：
更新日期：2001-01-01 00:00:00
abstract：BACKGROUND:Multiplexed amplicon melting is a closed-tube method for genotyping that does not require probes, real-time analysis, asymmetric PCR, or allele-specific PCR; however, correct differentiation of homozygous mutant and wild-type samples by melting temperature (T(m)) analysis requires high-resolution melting ana...
journal_title：Clinical chemistry
pub_type： 杂志文章
doi：10.1373/clinchem.2007.097121
更新日期：2008-01-01 00:00:00
abstract：:Concentrations of free thyroxin (T4) and free triiodothyronine (T3) were measured in sera from pregnant women, in subjects with congenitally increased or decreased thyroxin-binding globulin (TBG), and in euthyroid controls. Measured free hormone concentrations were compared with calculated values for free hormone deri...
journal_title：Clinical chemistry
pub_type： 杂志文章
doi：
更新日期：1983-08-01 00:00:00
abstract：:We describe a modification of the MacGee method [Anal. Chem. 42, 421 (1970)] for rapid determination of phenytoin (diphenylhydantoin) in plasma by gas-liquid chromatography, in which an ethylaing reagent is used instead of the more common methylating reagents. With this modification, several N-methylated antiepileptic...
journal_title：Clinical chemistry
pub_type： 杂志文章
doi：
更新日期：1975-05-01 00:00:00
abstract：:We developed a fluorometric method for determining delta-aminolevulinic acid (ALA) in urine of lead workers. A high-performance liquid chromatograph (HPLC) equipped with a fluorescence HPLC monitor is used. The detection limit for aqueous ALA is 20 micrograms/L (15 pmol of ALA in the 100-microL sample). The working li...
journal_title：Clinical chemistry
pub_type： 杂志文章
doi：
更新日期：1987-09-01 00:00:00
abstract：BACKGROUND:Insulin, growth hormone (GH), and growth factors (insulin-like growth factors [IGFs] and their binding proteins [IGFBPs]) are known to influence fetal growth and also the synthesis/secretion of the recently discovered hormones leptin and ghrelin. METHODS:In 153 delivering mothers and their offspring at birt...
journal_title：Clinical chemistry
pub_type： 杂志文章
doi：10.1373/clinchem.2007.095299
更新日期：2008-03-01 00:00:00
abstract：:The ultraviolet fluorescence emission spectra of sera from apparently healthy persons and of sera from cancer patients frequently show significantly different curve shapes. A biparametric fluorescence method has been developed to use these deviations to detect patients with malignant diseases (Clin Chem 1986;32:1974-8...
journal_title：Clinical chemistry
pub_type： 杂志文章
doi：
更新日期：1990-11-01 00:00:00
abstract：BACKGROUND:The next-generation, high-sensitivity cardiac troponin assays can measure quantifiable concentrations of cTn in a majority of individuals, but there are few studies assessing these assays for risk stratification. The present study was undertaken to determine if a research hs-cTnI assay can be useful for pred...
journal_title：Clinical chemistry
pub_type： 杂志文章
doi：10.1373/clinchem.2009.127241
更新日期：2009-10-01 00:00:00
