title: Measurement of serum-phosphate concentration in immunoglobulin G monoclonal gammopathy after PEG-precipitation.
abstract: BACKGROUND
  Spurious hyperphosphatemia is a relatively common phenomenon in patients with monoclonal gammopathy which can compromise patient safety. A cost-effective routine method is desirable for laboratories to reduce or eliminate the protein interference.
  
  
  METHODS
  A protein free sample was obtained after precipitation with PEG-6000 (polyethylene glycol). S-phosphate concentration was measured with routine wet chemistry method in normal and monoclonal gammopathy samples before and after precipitation. Monoclonal samples were also measured by dry chemistry that includes an ultrafiltration step. The protein pattern before and after precipitation was checked by electrophoresis.
  
  
  RESULTS
  No effect of PEG precipitation on S-phosphate concentration was demonstrated in normal serum. After PEG precipitation of proteins in monoclonal gammopathies serum wet chemistry gave the same results as dry chemistry i.e. after ultrafiltration.
  
  
  CONCLUSIONS
  PEG precipitation of proteins offers a cost-effective method to eliminate protein interferences in monoclonal gammopathies.
authors.affiliation: Department of Biochemistry, Peerless Hospital & B K Roy Research Center, Kolkata, India. Electronic address: dr_sutirtha@yahoo.com.
authors.forename: Sutirtha
authors.initials: S
authors.lastname: Chakraborty
authors.affiliation: Department of Clinical Chemistry, Karolinska University Hospital, Stockholm, Sweden.
authors.forename: Anders
authors.initials: A
authors.lastname: Kallner
mesh_terms: D001774:Blood Chemical Analysis / Q000379:methods*; D011232:Chemical Precipitation; D006801:Humans; D054559:Hyperphosphatemia / Q000097:blood; D007074:Immunoglobulin G / Q000097:blood; D010265:Paraproteinemias / Q000097:blood*; D010710:Phosphates / Q000097:blood*; D011092:Polyethylene Glycols / Q000737:chemistry; D012016:Reference Values
chemical_list: D007074:Immunoglobulin G; D010710:Phosphates; D011092:Polyethylene Glycols
keywords: Ig G kappa; Immunoglobulin; Interference; PEG; Phosphate; Vitros