![Immunoassays
• POCT testing that utilizes immunoassays relies
on antibodies to bind to a specific target when
the concentration exceeds a certain
threshold.[14] Targets in immunoassays for
POCT can encompass a wide range of
substances, including proteins, drugs, and
pathogens. POCTs are available in various
formats, including both individual tests and
platforms with multiple built-in tests
14](https://image.slidesharecdn.com/pointofcaretesting-240504143620-135f5845/85/Point-of-Care-Testing-in-selected-laboratory-14-320.jpg)
Point of Care Testing in selected laboratory
- 1. Point of Care Testing
- 2. Objectives • Identify appropriate indications for point-of-care testing based on patient presentation and clinical scenario. • Apply quality control measures and perform regular maintenance and calibration of point-of-care testing equipment to ensure accurate and reliable results. • Implement point-of-care testing procedures following established protocols, including proper specimen collection, handling, and storage. • Collaborate with other healthcare professionals in the interpretation and integration of point-of-care test results into patient management plans. 2
- 3. Introduction • POCT is clinical laboratory testing conducted close to the site of patient care where care or treatment is provided. • It provides rapid turnaround of test results with the potential to generate a result quickly so that appropriate treatment can be implemented, leading to improved clinical or economic outcomes compared to laboratory testing. 3
- 4. Introduction • POCT can be performed by various healthcare professionals and, in some cases, even by patients themselves. • By leveraging the expertise of different healthcare professionals, POCT can be effectively integrated into patient care, leading to improved outcomes and patient satisfaction. 4
- 5. Introduction • Traditional laboratory testing typically involves a multiple- step process that includes collecting samples from the patient at the bedside or the clinic, transporting them to a centralized laboratory (often located far away), and then subjecting the samples to several processing steps. • The delay in treatment caused by the time-consuming traditional laboratory testing can hinder timely clinical decision-making. • POCT addresses this challenge by bringing the laboratory to the patient. Portable and handheld testing devices enable healthcare workers to perform rapid testing on samples, significantly reducing the time needed for medical decision- making. 5
- 6. Features of POCT • POCT should be simple to use. • Reagents and consumables should have durable resistance during storage and use. • POCT results should align with established laboratory methods. • POCT should ensure safety during testing. 6
- 7. ASSURED Guidelines This are key criteria for effective POCT, as proposed by the World Health Organization (WHO) • Affordable, • Sensitive, • Specific, • User-friendly, • Rapid, • Robust, • Equipment-free,(means no complex equipment required) • and Delivered (to the end user) 7
- 8. Specimen Requirements and Procedure • Adhering to the manufacturer's instructions for use (MIFU) or package insert is crucial in ensuring accurate testing in POCT. • It is recommended to wait at least 15 minutes after a blood transfusion before drawing a sample for POCT. • Samples collected for blood gas analysis are susceptible to changes in oxygen partial pressure; therefore, it is crucial to maintain anaerobic conditions during sample collection to ensure accurate laboratory values. 8
- 9. Classification of POCT • POCT testing devices are classified based on the testing modality and the test size. 9
- 10. Testing modalities Testing Strips and Lateral-flow Testing • The most basic POCT takes advantage of an interaction between an analyte and a substance, usually impregnated or contained, so that a sample can be added or mixed in a controlled manner. • An example is using test strips (eg, urine test strips). These strips are generally dried, porous matrices with impregnated carrier elements that interact with the analyte(s) when exposed. • The interaction between the analyte and the testing reagents often involves a chemical reaction that produces a color change. • This color change can be interpreted as a binary value indicating the presence or absence of the analyte or as an indication of the analyte concentration using a scale (eg, trace protein, 1+, 2+, 3+). 10
- 11. • A more complex approach to POCT is lateral-flow testing. This type of diagnostic testing utilizes a layer of supporting material, such as porous paper of cellulose fiber filters or woven meshes. The supporting material contains capillary beds to whisk fluid samples to location(s) on the support material with substances that react with measured analytes in the sample. A well-known example is the at-home pregnancy test, which commonly utilizes an immunoassay to detect the presence of human chorionic gonadotropin (hCG, specifically beta-hCG) in urine. 11
- 12. • Urine is exposed to one end of the supporting material in the test device; capillary beds then move the urine through the supporting material to specific sites that react with beta-hCG. • This configuration commonly has 2 lines of reactive material, one that serves as the control and another that indicates a binary yes or no indication. • The test is positive if both lines (also known as stripes) appear or change color and negative if only the control line is visible. • Failure of the control line to appear indicates an invalid or faulty test, which could result from a manufacturing defect, damage, or expired test 12
- 13. • In many instances, POCTs that utilize simple test strips or lateral-flow testing provide qualitative or semiquantitative results and do not provide precise 13
- 14. Immunoassays • POCT testing that utilizes immunoassays relies on antibodies to bind to a specific target when the concentration exceeds a certain threshold.[14] Targets in immunoassays for POCT can encompass a wide range of substances, including proteins, drugs, and pathogens. POCTs are available in various formats, including both individual tests and platforms with multiple built-in tests 14
- 15. • Could be Competitive assays or non- competitive assays • Unlike simple test strip-based POCT, immunoassay POCT provides quantitative information for specific analytes. 15
- 16. Antigen-based Testing • POCT, which involves the detection of known antigens or antibodies specific to a particular disease or disease state, has been widely employed as a common practice in healthcare. • Immunoassay-based POCT is commonly used to rapidly detect group A Streptococcus, mononucleosis, and influenza A and B. These tests utilize immunoassays that bind specific antigens or antibodies. • Immunoassay-based POCT offers a fast turnaround time (TAT) but may have lower sensitivities and specificities compared to traditional laboratory and molecular testing methods. 16
- 17. Molecular POCT • The demand for molecular POCT with high sensitivity and specificity and a relatively short turnaround time (although longer than antigen- based testing) spurred its development. • This form of testing detects DNA or RNA sequences indicative of the presence of disease. Nucleic acid amplification testing (NAAT) is used to identify DNA or RNA in small test samples. T • he nucleic acids of interest are replicated to increase their concentration (ie, amplify them) so they are easier to detect 17
- 18. • There are various forms of this testing, including reverse transcription polymerase chain reaction (RT-PCR) and isothermal amplification methods such as nicking endonuclease amplification reaction (NEAR) and transcription-mediated amplification (TMA). 18