Interference in a homogeneous assay for low-density lipoprotein cholesterol by lipoprotein X
-
Ileana Herzum
Abstract
Background: Homogeneous assays for cholesterol in low-density lipoprotein (LDL) are currently in wide use for guideline-based diagnosis and monitoring of dyslipaemic or coronary conditions. In some sera from patients with impaired liver function, we measured implausibly low LDL concentrations using a sugar compound-based assay [LDL-cholesterol (LDL-C), Roche Diagnostics]. We investigated whether an interfering factor, possibly associated with cholestasis, is consistently responsible for this disturbance.
Methods: We compared results of the LDL-C assay in samples with implausible (n=158) and plausible (n=65) LDL concentrations with those of another assay based on two selective detergents (LDLD, Beckman Coulter) and with sequential density ultracentrifugation. We measured total bilirubin, triglycerides, bile acids and lipoprotein X (Lp X) concentrations in samples with the described disturbance and examined the effect of bile salt addition to normal samples.
Results: The LDL-C assay was negatively biased compared to the LDLD assay (bias –0.63 mmol/L) and sequential density ultracentrifugation (bias –0.85 mmol/L) in samples with an implausible lipoprotein profile, but showed good method agreement in all other samples. The bile acid concentration did not correlate with the LDL bias, and addition of bile acids showed no interference with the LDL-C assay. The Lp X concentration correlated with the bias between the LDL-C and LDLD assays (R=0.66, p<0.0001); there was no interference with the LDLD assay, even at high Lp X concentrations.
Conclusions: We conclude that the LDL-C assay is subject to interference by Lp X and can provide grossly negatively biased results in cholestatic conditions. In such patients, LDL measurement with an assay based on a different method should be performed.
Clin Chem Lab Med 2007;45:667–71.
©2007 by Walter de Gruyter Berlin New York
Articles in the same Issue
- 6th Conference on Homocysteine Metabolism, World Congress on Hyperhomocysteinemia, Saarbruecken/Germany June 5-9, 2007
- The role of ethylenediamine tetraacetic acid (EDTA) as in vitro anticoagulant for diagnostic purposes
- Cervical screening in the 21st century: the case for human papillomavirus testing of self-collected specimens
- Influence of apolipoprotein E polymorphism on serum lipid and lipoprotein changes: a 21-year follow-up study from childhood to adulthood. The Cardiovascular Risk in Young Finns Study
- Association of lipase lipoprotein polymorphisms with myocardial infarction and lipid levels
- Validation of a reverse-hybridization StripAssay for the simultaneous analysis of common α-thalassemia point mutations and deletions
- HLA-DQA1 and -DQB1 allele typing in southern Taiwanese women with breast cancer
- Association of a polymorphism in the promoter of the cellular retinoic acid-binding protein II gene (CRABP2) with increased circulating low-density lipoprotein cholesterol
- Frequency of two human glutathione-S-transferase omega-1 polymorphisms (E155 deletion and E208K) in Ovambo and Japanese populations using the PCR-based genotyping method
- Transthyretin amyloidosis in a patient of Iranian-Jewish extraction: a second Israeli-Jewish case
- Relationship between neurological outcome and early oxidative changes in erythrocytes in head injury patients
- Mesothelin family proteins and diagnosis of mesothelioma: analytical evaluation of an automated immunoassay and preliminary clinical results
- Prevalence of insulin resistance and prediction of glucose intolerance and type 2 diabetes mellitus in women with polycystic ovary syndrome
- A simple high-throughput method for the determination of plasma methylmalonic acid by liquid chromatography-tandem mass spectrometry
- Effects of gestational and lactational choline deprivation on brain antioxidant status, acetylcholinesterase, (Na+,K+)- and Mg2+-ATPase activities in offspring rats
- Use of novel serum markers in clinical follow-up of Sertoli-Leydig cell tumours
- Measurement of calcitonin by immunoassay analyzers
- Interference in a homogeneous assay for low-density lipoprotein cholesterol by lipoprotein X
- Quality indicators and specifications for key processes in clinical laboratories: a preliminary experience
- Analytical and clinical performance of three natriuretic peptide tests in the emergency room
- Quality of serum creatinine measurement in light of EQA programs
- Decreased plasmalogen concentration as a surrogate marker of oxidative stress in patients presenting with acute coronary syndromes or supraventricular tachycardias
- Comparison between AlaTOP and IP8 inhalant panels on the Immulite 2000 analyzer
- External quality assessment of urinary methylmalonic acid quantification – results of a pilot study
Articles in the same Issue
- 6th Conference on Homocysteine Metabolism, World Congress on Hyperhomocysteinemia, Saarbruecken/Germany June 5-9, 2007
- The role of ethylenediamine tetraacetic acid (EDTA) as in vitro anticoagulant for diagnostic purposes
- Cervical screening in the 21st century: the case for human papillomavirus testing of self-collected specimens
- Influence of apolipoprotein E polymorphism on serum lipid and lipoprotein changes: a 21-year follow-up study from childhood to adulthood. The Cardiovascular Risk in Young Finns Study
- Association of lipase lipoprotein polymorphisms with myocardial infarction and lipid levels
- Validation of a reverse-hybridization StripAssay for the simultaneous analysis of common α-thalassemia point mutations and deletions
- HLA-DQA1 and -DQB1 allele typing in southern Taiwanese women with breast cancer
- Association of a polymorphism in the promoter of the cellular retinoic acid-binding protein II gene (CRABP2) with increased circulating low-density lipoprotein cholesterol
- Frequency of two human glutathione-S-transferase omega-1 polymorphisms (E155 deletion and E208K) in Ovambo and Japanese populations using the PCR-based genotyping method
- Transthyretin amyloidosis in a patient of Iranian-Jewish extraction: a second Israeli-Jewish case
- Relationship between neurological outcome and early oxidative changes in erythrocytes in head injury patients
- Mesothelin family proteins and diagnosis of mesothelioma: analytical evaluation of an automated immunoassay and preliminary clinical results
- Prevalence of insulin resistance and prediction of glucose intolerance and type 2 diabetes mellitus in women with polycystic ovary syndrome
- A simple high-throughput method for the determination of plasma methylmalonic acid by liquid chromatography-tandem mass spectrometry
- Effects of gestational and lactational choline deprivation on brain antioxidant status, acetylcholinesterase, (Na+,K+)- and Mg2+-ATPase activities in offspring rats
- Use of novel serum markers in clinical follow-up of Sertoli-Leydig cell tumours
- Measurement of calcitonin by immunoassay analyzers
- Interference in a homogeneous assay for low-density lipoprotein cholesterol by lipoprotein X
- Quality indicators and specifications for key processes in clinical laboratories: a preliminary experience
- Analytical and clinical performance of three natriuretic peptide tests in the emergency room
- Quality of serum creatinine measurement in light of EQA programs
- Decreased plasmalogen concentration as a surrogate marker of oxidative stress in patients presenting with acute coronary syndromes or supraventricular tachycardias
- Comparison between AlaTOP and IP8 inhalant panels on the Immulite 2000 analyzer
- External quality assessment of urinary methylmalonic acid quantification – results of a pilot study
