Clinical Assays for Proteins in Plasma and Serum

Current issue of Clinical chemistry has an excellent article by N. Leigh Anderson of Plasma Proteome Institute, Washington, DC, on FDA approved clinical assays for proteins from plasma and serum. The article has tons of information on FDA approved protein tests and other tests not approved by FDA but offered by large reference laboratories i.e. Quest Diagnostics, ARUP and Mayo Medical Laboratories. What I found interesting is the reimbursement cost of each test; this information is very relevant when designing biosensor for diagnostic applications.

Few key points from the article

  • There are 109 unique protein analytes in serum/plasma for which FDA approved tests are available
  • 62 additional FDA approved tests are available for proteins that fall out of definition of first list. These proteins are autoantibodies, proteins with posttranslation modifications, proteins in blood cells and protein complexes.
  • Additional 96 protein tests that are not FDA approved are offered by key reference laboratories.
  • 80% of the 109 FDA approved tests were developed before 1993 and since then only 22 additional tests have been introduced at the rate of 1.5 tests per year

The dismal rate of new tests points toward the lack of well validated protein markers and not necessarily the lack of detection platforms. Most of the assays (~80) still use immunoassays that should be easily adaptable to biosensing platforms.

Article points out that Mass spectrometry (MS) may prove to be a “positive disruptive change” by providing specificity and multiplexing capabilities that current immunoassays lack. I am not convinced with this argument-MS may prove to be valuable discovery tool but immunoassay in its myriad incarnations -ELISA, protein arrays, bead arrays (i.e. luminex), dip-stick, biosensors (i.e. Bio-barcode)-may be difficult to beat on price, performance, reliability and convenience.

Need for personalized medicine, companion diagnostics, infectious diseases, biothreats among others may still shake up the field in coming years and provide opportunities for folks developing biosensors.

Overall great paper from a key opinion leader and a must read! Check out other papers in the same issue of Clinical Chemistry!


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