POCT methods include manual methods, such as urine dipsticks and test kits, hand-held devices, and bench top instruments.
Rapid test kits and dipsticks usually provide qualitative or semi-quantitative results. These are used in the differential diagnosis and treatment of the patient. Dipsticks for chemical analysis of urine are pads impregnated with chemicals. The presence of a chemical reaction will result in a change in color that can either be read manually or with a small bench top instrument designed for that purpose. These bench top instruments operate with the principle of light reflection at specified wavelengths that represent specific color change and intensity. Test kits used in POCT most often employ lateral flow test methods and, more recently, optical immunoassay. Some rapid testing methodologies have been adapted to small bench top instrumentation to incorporate chromatographic immunoassay, fluorescent immunoassay, and molecular technologies.
Handheld and small benchtop chemistry analyzers represent methods that produce quantitative results for POCT. Most handheld glucose meters use electrochemical analysis principles. Testing methods vary and include electromechanical, photometric, electrochemical, and chemiluminescence technology. Test principles vary by instrument and specific assay. Most POC analyzers have on board instrument QC that is monitored daily for validation of instrument function. As with all test kits, the manufacturer's instructions must be followed for proper operation and to maintain the FDA-approved level of complexity of the instrument.
Appropriate procedures and operating instructions must be in place for the test kits, instruments, and methodologies in use in each specific POCT location. Manufacturers often provide procedures in Clinical and Laboratory Standards Institute (CLSI) format, as well as package inserts for all kits and test methodologies. Either of these formats may serve as instructions for end users. The documents do not have to be rewritten or recreated. The laboratory director must approve the use of the documents as test instructions. The laboratory director's approval must be noted with a signature and in use date on the documents.
