Human Clinical Biochemistry comprises the study of metabolic and molecular processes in relation to both physiological and pathological changes or those induced by therapeutic actions. For this study, clinical biochemistry applies the methods, techniques and procedures of analytical chemistry and biochemistry in order to obtain useful information and participate in its interpretation, for the prevention, diagnosis , prognosis and evolution of the disease, as well as your response to treatment.
Emergence of Clinical Biochemistry
Urine was the first fluid that was used for the study of diseases because of its easy obtaining and availability in high quantities. Assessment of urine color was part of medicine in Babylon , Egypt, and India . In the fourth century BC , Hippocrates raised the importance of urinalysis and studied this fluid in relation to its consistency, color, and sediment. The first useful diagnostic chemical test of urine was the demonstration by Richard Bright in 1827on the presence of proteins in urine in some patients with edema. Subsequently, different tests were developed to determine components in the urine. The studies of human blood began in the XIX century , from the therapeutic bloodletting that were used; these required copious amounts of blood. In 1838 , George Rees , in the United Kingdom , demonstrated the presence of glucose in the blood of a diabetic patient from 360 mL of blood, isolating and evaporating the sample until obtaining glucose crystals. In this way, in 1848 Garrod obtained sodium urate crystals in the blood of patients with gout.
Object of Study
- The structure-function relationship of biomolecules .
- The supramacromolecular organizations that form the basis of cellular structures, tissues, and the body.
- The mechanisms of action of biocatalysts .
- The molecular bases of the conservation, transfer and expression of genetic information.
- Cellular metabolic processes , their tissue specificity and their regulatory mechanisms.
- Biochemical alterations that are causes, complications or accompany various diseases.
A clinical laboratory is the place where experimental work is carried out and biochemical, serological, histological, cytological and bacteriological analyzes and examinations are carried out. The most frequent activity of a clinical biochemistry laboratory is the performance of quantitative chemical analyzes on human biological fluids (less frequently: semi-quantitative and qualitative analyzes).
It includes tests for the study of the metabolism of carbohydrates , proteins , lipids , water and electrolytes , and the acid-base balance ; serum enzymes , intermediate or final products of metabolism, trace elements , hormones and drug levels in the blood, such as: determination of glycemia , acid , creatinine , among others.
It includes a group of so-called basic or routine tests ( hemoglobin , hematocrit , blood cell counts, examination of the colored area of peripheral blood, calculation of corpuscular constants, erythrocyte sedimentation rate) and more specialized tests, such as studies of hemolytic and nutritional anemias , the examination of the colored extensions of bone marrow ( medullogram ), the cytochemical colorations and some studies carried out with the use of radionuclides , molecular probes or electron microscopy .
They include all the tests that allow exploring the mechanisms of blood coagulation , fibrinolysis, and thrombocyte activity , such as: clotting time, prothrombin time, thromboplastin time , fibrinogen , etc.
Includes a wide range of tests for the study of autoimmunity, immunodeficiencies, typing for transplants, immunogenicity tests such as protein electrophoresis , immunoglobulin quantification , immunoelectrophoresis , enzyme- linked immunosorbent assay [[Enzyme-Linked ImmunoSorbent Assay] ], Western blot , flow cytometry , BIAcore , among others.
Chemical and cytological examination
From urine, cerebrospinal fluid (CSF), amniotic or synovial fluid , seminal fluid , saliva , exudates and transudates .
Recently introduced in the clinical laboratory, deoxyribonucleic acid (DNA) probes are used for the study of infectious, neoplastic and genetic diseases, as well as to increasingly replace the classical methods of studying the immune system. The DNA available for a reaction is expanded by means of the polymerase chain reaction (PCR), which results in faster and more specific diagnoses and opens up possibilities that were unsuspected a few years ago.
In every laboratory there are potential risks that require special attention. If to this we add the fact that the clinical laboratory works with human biological samples, the danger increases considerably. To prevent possible accidents it is necessary to take a series of measures, put up a series of barriers.
Primary barriers Those located around the origin of the risk. For example, in cases of spills or splashes, use disinfectants ; if there is a risk of chemical emanations, extraction hoods should be used; and if there is a risk of dangerous microorganisms, use the biosafety manual.
Secondary barriers They are located in the operator’s circle. They include: – Vaccination of laboratory personnel. – Occupational health programs. – Gowns and gloves are recommended when dealing with blood, materials related to hepatitis and Acquired Immune Deficiency Syndrome (AIDS) , and for the management of pathogens; care must be taken not to transform them into a vehicle for the transmission of infection. The use of glasses is also recommended.
Tertiary barriers They are located around the laboratory and prevent its risks from having an impact on the community:
- Do not leave the laboratory with work clothes.
- Existence of containers for biohazard material and incinerators for contaminated waste.
- The laboratory, or research area, should be away from unqualified personnel.
In the clinical laboratory, analyzes and examinations of different types are carried out: serological, cytological and bacteriological. In any case, it is essential to know the analytical method to be used, understanding by such, the set of written instructions that describe the procedure, materials and equipment that the analyst needs to obtain the results.
Automatic analyzers for clinical chemistry are equipment designed to mechanize manual procedures for the determination of chemicals and enzymes. The fundamental components are:
- Specimen loading device (generally the same extraction tubes after centrifugation).
- Specimen identification system (they have barcode readers for specimen identification).
- Device for taking and dispensing the specimens, which transfers them from their container to the reaction cell.
- Reagent dispensing system (pipettes).
- Specimen and reagent mixing device (in reaction cells).
- Disposable or reusable reaction cells.
- Incubation bath .
- Detection system: they usually detect spectrophotometric , colorimetric measurements , etc.
- Amplifier and analog / digital converter.
- Computer or data analyzer.