Chemical pathology
Encyclopedia
Clinical chemistry is the area of clinical pathology
that is generain concerned with analysis of bodily fluids.
The discipline originated in the late 19th century with the use of simple chemical tests for various components of blood and urine. Subsequent to this, other techniques were applied including the use and measurement of enzyme
activities, spectrophotometry
, electrophoresis
, and immunoassay
.
Most current laboratories are now highly automated to accommodate the high workload typical of a hospital laboratory. Tests performed are closely monitored and quality controlled.
All biochemical tests come under chemical pathology. These are performed on any kind of body fluid, but mostly on serum or plasma
. Serum is the yellow watery part of blood that is left after blood has been allowed to clot and all blood cells have been removed. This is most easily done by centrifugation, which packs the denser blood cells and platelets to the bottom of the centrifuge tube, leaving the liquid serum fraction resting above the packed cells. This initial step before analysis has recently been included in instruments that operate on the "integrated system" principle. Plasma is in essence the same as serum, but is obtained by centrifuging the blood without clotting. Plasma is obtained by centrifugation before clotting occurs. The type of test required dictates what type of sample is used.
A large medical laboratory
will accept samples for up to about 700 different kinds of tests. Even the largest of laboratories rarely do all these tests themselves, and some must be referred to other labs.
This large array of tests can be further sub-categorised into sub-specialities of:
Clinical pathology
Clinical pathology , Laboratory Medicine , Clinical analysis or Clinical/Medical Biology , is a medical specialty that is concerned with the diagnosis of disease based on the laboratory analysis of bodily fluids, such as...
that is generain concerned with analysis of bodily fluids.
The discipline originated in the late 19th century with the use of simple chemical tests for various components of blood and urine. Subsequent to this, other techniques were applied including the use and measurement of enzyme
Enzyme
Enzymes are proteins that catalyze chemical reactions. In enzymatic reactions, the molecules at the beginning of the process, called substrates, are converted into different molecules, called products. Almost all chemical reactions in a biological cell need enzymes in order to occur at rates...
activities, spectrophotometry
Spectrophotometry
In chemistry, spectrophotometry is the quantitative measurement of the reflection or transmission properties of a material as a function of wavelength...
, electrophoresis
Electrophoresis
Electrophoresis, also called cataphoresis, is the motion of dispersed particles relative to a fluid under the influence of a spatially uniform electric field. This electrokinetic phenomenon was observed for the first time in 1807 by Reuss , who noticed that the application of a constant electric...
, and immunoassay
Immunoassay
An immunoassay is a biochemical test that measures the presence or concentration of a substance in solutions that frequently contain a complex mixture of substances. Analytes in biological liquids such as serum or urine are frequently assayed using immunoassay methods...
.
Most current laboratories are now highly automated to accommodate the high workload typical of a hospital laboratory. Tests performed are closely monitored and quality controlled.
All biochemical tests come under chemical pathology. These are performed on any kind of body fluid, but mostly on serum or plasma
Blood plasma
Blood plasma is the straw-colored liquid component of blood in which the blood cells in whole blood are normally suspended. It makes up about 55% of the total blood volume. It is the intravascular fluid part of extracellular fluid...
. Serum is the yellow watery part of blood that is left after blood has been allowed to clot and all blood cells have been removed. This is most easily done by centrifugation, which packs the denser blood cells and platelets to the bottom of the centrifuge tube, leaving the liquid serum fraction resting above the packed cells. This initial step before analysis has recently been included in instruments that operate on the "integrated system" principle. Plasma is in essence the same as serum, but is obtained by centrifuging the blood without clotting. Plasma is obtained by centrifugation before clotting occurs. The type of test required dictates what type of sample is used.
A large medical laboratory
Medical laboratory
A medical laboratory or clinical laboratory is a laboratory where tests are done on clinical specimens in order to get information about the health of a patient as pertaining to the diagnosis, treatment, and prevention of disease.-Departments:...
will accept samples for up to about 700 different kinds of tests. Even the largest of laboratories rarely do all these tests themselves, and some must be referred to other labs.
This large array of tests can be further sub-categorised into sub-specialities of:
- General or routine chemistry - commonly ordered blood chemistries (e.g., liver and kidney function tests).
- Special chemistry - elaborate techniques such as electrophoresisProtein electrophoresisProtein electrophoresis is a method for analysing the proteins in a fluid or an extract. The electrophoresis may be performed with a small volume of sample in a number of alternative ways with or without a supporting medium: SDS polyacrylamide gel electrophoresis Protein electrophoresis is a method...
manual testing methods. - Clinical endocrinologyEndocrine pathologyEndocrine pathology is the subspecialty of surgical pathology which deals with the diagnosis and characterization of neoplastic and non-neoplastic diseases of organs of the endocrine system, including the thyroid, parathyroids, exocrine pancreas, and adrenal glands....
- the study of hormoneHormoneA hormone is a chemical released by a cell or a gland in one part of the body that sends out messages that affect cells in other parts of the organism. Only a small amount of hormone is required to alter cell metabolism. In essence, it is a chemical messenger that transports a signal from one...
s, and diagnosis of endocrine disorders. - ToxicologyToxicologyToxicology is a branch of biology, chemistry, and medicine concerned with the study of the adverse effects of chemicals on living organisms...
- the study of drugs of abuse. - Therapeutic Drug Monitoring - measurement of therapeutic medications blood levels to optimize dosage.
- UrinalysisUrinalysisA urinalysis , also known as Routine and Microscopy , is an array of tests performed on urine, and one of the most common methods of medical diagnosis...
- chemical analysis of urine for a wide array of diseases, along with other fluids such as CSFCSF-Biology and Medicine:* Cerebrospinal fluid* Colony-Stimulating Factor* Cancer slope factor* Classical swine fever* Certain safety factor-Military:* Central Security Forces , an Egyptian paramilitary force...
and effusionsEffusionIn physics, effusion is the process in which individual molecules flow through a hole without collisions between molecules. This occurs if the diameter of the hole is considerably smaller than the mean free path of the molecules... - Fecal analysis - mostly for detection of gastrointestinal disorders.
Panel tests
A set of commonly ordered tests are combined into a panel:- Basic metabolic panelBasic metabolic panelA basic metabolic panel is a set of seven or eight blood chemical tests. It is one of the most common lab tests ordered by health care providers. It provides key information that has a variety of applications in guiding the medical management of a patient...
(BMP) - 7 tests - sodium, potassium, chloride, bicarbonate, blood urea nitrogen (BUN), creatinine, glucose - Comprehensive metabolic panelComprehensive metabolic panelThe comprehensive metabolic panel, or chemical screen, is a panel of 14 blood tests which serves as an initial broad screening tool for physicians, nurse practitioners and physician assistants...
(CMP) - 14 tests - above BMP plus calcium, total protein, albumin, alkaline phosphatase (ALP), alanine amino transferase (ALT), aspartate amino transferase (AST), bilirubin