title: Negative interference by rheumatoid factor of plasma B-type natriuretic peptide in chemiluminescent microparticle immunoassays.
abstract: BACKGROUND
  The chemiluminescent microparticle immunoassay (CMIA) is widely used for the quantitative determination of B-type natriuretic peptide (BNP) in human ethylenediaminetetraacetic acid plasma. Rheumatoid factor (RF) is usually thought to result in a positive interference in immunoassays, but it is not clear whether its presence in plasma can lead to interferences in the CMIA of BNP.
  
  
  METHODS
  The estimation of BNP recovery was carried out by diluting high-concentration BNP samples with RF-positive or RF-negative plasma at a ratio of 1:9. The diluted samples were then tested using the ARCHITECT i2000 System and ARCHITECT BNP Reagent Kits and the recovery was then calculated.
  
  
  RESULTS
  When the RF level ranged from 48 to 1420 IU/mL, the average recovery of BNP was 79.29% and 91.61% in the RF-positive and RF-negative plasma samples, respectively, and was thus significantly lower in the group of RF-positive plasma samples than in the group of RF-negative plasma samples. At a dilution of 1:16, the measured BNP level increased by >36% in six of the seven RF-positive plasma samples. The recovery of BNP increased significantly in the RF-positive plasma samples after pretreatment with IgG-sensitive latex particles. In addition, The BNP recovery was not significantly related to the plasma RF at concentrations ranging from 48 to 2720 IU/mL.
  
  
  CONCLUSIONS
  Measurement of BNP by CMIA is susceptible to interference from RF leading to predominantly (but not exclusively) lower results. Pretreatment of samples with blocking reagents is advisable prior to the initiation of denying patient's necessary treatment.
authors.affiliation: Department of Laboratory Medicine, Jingzhou First People's Hospital, Jingzhou, Hubei, China.
authors.forename: Wen
authors.initials: W
authors.lastname: Fan
authors.affiliation: Department of Laboratory Medicine, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China.
authors.forename: Lei
authors.initials: L
authors.lastname: Xu
authors.affiliation: Department of Laboratory Medicine, Jingzhou First People's Hospital, Jingzhou, Hubei, China.
authors.forename: Liangcai
authors.initials: L
authors.lastname: Xie
authors.affiliation: Department of Laboratory Medicine, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China.
authors.forename: Decai
authors.initials: D
authors.lastname: Yang
authors.affiliation: Department of Laboratory Medicine, Jingzhou First People's Hospital, Jingzhou, Hubei, China.
authors.forename: Xuezheng
authors.initials: X
authors.lastname: Liu
authors.affiliation: Department of Laboratory Medicine, Jingzhou First People's Hospital, Jingzhou, Hubei, China.
authors.forename: Jiajun
authors.initials: J
authors.lastname: Zhang
authors.affiliation: Department of Laboratory Medicine, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China.
authors.forename: Yirong
authors.initials: Y
authors.lastname: Li
authors.affiliation: Department of Obstetrics and Gynecology, Jingzhou First People's Hospital, Jingzhou, Hubei, China.
authors.forename: Cunjian
authors.initials: C
authors.lastname: Yi
mesh_terms: D006801:Humans; D007118:Immunoassay / Q000379:methods*; D008163:Luminescent Measurements / Q000379:methods*; D020097:Natriuretic Peptide, Brain / Q000097:blood*; D011933:Reagent Kits, Diagnostic; D015203:Reproducibility of Results; D012217:Rheumatoid Factor / Q000097:blood*; D012680:Sensitivity and Specificity
chemical_list: D011933:Reagent Kits, Diagnostic; D020097:Natriuretic Peptide, Brain; D012217:Rheumatoid Factor