• Microparticle Enzyme Immunoassay (MEIA) 
   is an immunoassay method that utilizes 
   the isolation of antibody/antigen 
   complexes on a solid phase surface of 
   small beads called microparticles.
  •  MEIA has been widely adapted to 
   automate the measurement of large 
   molecules such as markers associated 
   with cardiac, fertility, cancer, metabolic, 
   hepatitis, and thyroid testing.
  • Chemiluminecent microparticle 
   immunoassay CMIA used for quantitative 
   determination of human thyroid 
   stimulating hormone in serum and 
   plasma.
  • In ARCHITECT  instrument, TSH assay is a 
   two-step immunoassay to determine the 
   presence of TSH in serum or plasma by 
   CMIA  technology with flexible assay 
   protocols referred to as chemiflex.
  • In the first step, sample, anti TSH antibody 
   coated paramagnetic micro particles and TSH 
   assay diluent are combined.  TSH present in 
   the sample binds to the anti TSH antibody 
   coated micro particles. After washing, anti- 
   alpha TSH acridinium labeled conjugate is 
   added in the second step.
  • Pre-trigger and trigger solutions are then 
   added to the reaction mixture: the resulting 
   chemiluminescent reaction is measured as 
   relative light units(RLUs).
  • A direct relationship exists between 
   the amount of TSH in the sample and 
   the RLUs detected by the instrument 
   optical system.