The New Weapon of Laboratory Medicine: In Vitro Diagnostics

  • In vitro diagnosis refers to the products and services that acquire clinical diagnostic information through testing human body samples (blood, body fluids, tissues, etc.) outside the human body, so as to judge diseases or bodily functions. In other words, in vitro diagnosis (IVD) refers to the process of using in vitro detection reagents and instruments to detect blood, body fluids, tissues and other samples for the purpose of disease prevention, diagnosis, treatment detection, post-observation, health evaluation and genetic disease prediction. Therefore, the core of in vitro diagnosis is in vitro detection reagents and detection instruments.

    IVD is a powerful tool for medical examination, which provides all-round (biochemical information, immune information, genetic information) and multi-level (qualitative, semi-quantitative, and quantitative) examination information and has become an important source of clinical diagnostic information. According to statistics, about 80% of clinical diagnostic information comes from in vitro diagnosis, and its cost accounts for less than 20% of medical expenses, so it has great commercial value and practical significance.

    In vitro diagnostic technology rapid development, from gene sequencing at the gene level, SNP screening, point mutation gene diagnosis, to biomarkers detection at the protein level, to detection of circulating tumor cells at the cellular level (CTC), thin layer liquid-based cytology (TCT), and to PET/CT at tissue level etc., are all in vitro diagnostic field. It is worth mentioning that biomarkers, such as colorectal cancer biomarkers, which are emerging technologies for in vitro diagnosis, play an important role in the diagnosis of cancer and are of landmark significance for cancer treatment. In general, in vitro diagnosis is becoming more convenient, faster, non - invasive and multi - information. According to the different testing principles or methods, it mainly includes clinical biochemical diagnosis, immune diagnosis, molecular biology diagnosis, hematology diagnosis, microbial diagnosis, urine diagnosis, instant diagnosis, etc., among which biochemical diagnosis, immune diagnosis, molecular biology diagnosis are the three main fields of clinical in vitro diagnosis.

    In the field of immune diagnosis, two representative techniques have to be mentioned: enzyme-linked immunity: ELISA and chemiluminescence immunoassay: CLIA. Enzyme-linked immunoassay is a solid phase immunoassay method developed from immune technology to detect trace substances in body fluids. As a special reagent analysis method, it is in the immunoenzymatic techniques developed on the basis of a new type of immunoassay technology. ELISA kit is the most widely used technique in enzyme immunoassay. The elisa kit development also promoted the development of ELISA. Chemiluminescence immunoassay (CLIA) is a combination of chemiluminescence determination technology and highly specific immune response, which is used for the detection and analysis of various antigens, haptens, antibodies, hormones, enzymes, fatty acids, vitamins and drugs. It is a new immunoassay technology developed after radioimmunoassay, enzyme-immunoassay, fluorescence immunoassay and time-resolved fluorescence immunoassay, and has been widely used in clinical diagnosis, life analysis, environmental science and other fields.

    According to different testing environments and conditions, in vitro diagnosis can also be divided into laboratory diagnosis and point of care testing(POCT). POCT is a method that can quickly detect the results by using portable analytical instruments or supporting reagents in the sampling site, and it has been rapidly developed and applied due to its advantages of "portability, simple operation and timeliness of results". One of the most common applications is myocardial infarction biomarkers. Myocardial markers can help to determine the presence and severity of ACS in patients as early as possible, so that appropriate treatment can be carried out in the early stage. There are only a few myocardial markers commonly used in clinical practice. Currently, troponin is the only available marker to detect heart damage. Other myocardial markers are not specific for heart injury and may be elevated in skeletal muscle injury, liver disease or kidney disease. In addition, many other myocardial markers are being studied, but their clinical value needs to be further clarified. In vitro diagnosis is an important source of clinical diagnostic information, which can provide important reference indicators for doctors' treatment plans and medication, and is an indispensable part of the medical system to ensure human health. In addition, it also plays a decisive role in the fields of eugenics, public health and disease prevention. The potential of in vitro diagnosis is still very great and it will certainly set off a new revolution in the academic field in the future.