The discipline originated in the late 19th century with the use of simple chemical reaction tests for various components of blood and urine. Many decades later, clinical chemists use automated analyzers in many clinical laboratories. These instruments perform experimental techniques ranging from pipetting specimens and specimen labelling to advanced measurement techniques such as spectrometry, chromatography, photometry, potentiometry, etc.[2] These instruments provide different results that help identify uncommon analytes, changes in light and electronic voltage properties of naturally-occurring analytes such as enzymes, ions, electrolytes, and their concentrations, all of which are important for diagnosing diseases.
Blood and urine are the most common test specimens clinical chemists or medical laboratory scientists collect for clinical routine tests, with a main focus on serum and plasma in blood.[3] There are now many blood tests and clinical urine tests with extensive diagnostic capabilities. Some clinical tests require clinical chemists to process the specimen before testing. Clinical chemists and medical laboratory scientists serve as the interface between the laboratory side and the clinical practice, providing suggestions to physicians on which test panel to order and interpret any irregularities in test results that reflect on the patient's health status and organ system functionality.[4] This allows healthcare providers to make more accurate evaluation of a patient's health and to diagnose disease, predicting the progression of a disease (prognosis), screening, and monitoring the treatment's efficiency in a timely manner. The type of test required dictates what type of sample is used.
Common Analytes
Some common analytes that clinical chemistry tests analyze include:
A physician may order many laboratory tests on one specimen, referred to as a test panel, when a single test cannot provide sufficient information to make a swift and accurate diagnosis and treatment plan. A test panel is a group of many tests a clinical chemists do on one sample to look for changes in many analytes that may be indicative of specific medical concerns or the health status of an organ system.[5] Thus, panel tests provide a more extensive evaluation of a patient's health, have higher predictive values for confirming or disproving a disease, and are quick and cost-effective.
Metabolic Panel
A Metabolic Panel (MP) is a routine group of blood tests commonly used for health screenings, disease detection, and monitoring vital signs of hospitalized patients with specific medical conditions. MP panel analyzes common analytes in the blood to assess the functions of the kidneys and liver, as well as electrolyte and acid-base balances. There are two types of MPs - Basic Metabolic Panel (BMP) or Comprehensive Metabolic Panel (CMP).[6]
Basic Metabolic Panel
BMP is a panel of tests that measures eight analytes in the blood's fluid portion (plasma). The results of the BMP provide valuable information about a patient's kidney function, blood sugar level, electrolyte levels, and the acid-base balance. Abnormal changes in one or more of these analytes can be a sign of serious health issues:
Sodium, Potassium, Chloride, and Carbon Dioxide: they are electrolytes that have electrical charges that manage the body’s water level, acid-base balance in the blood, and kidney function.[7]
Urea and Creatinine: These are waste products that the kidney filters out from blood. Urea measurements are helpful in detecting and treating kidney failure and related metabolic disorders, whereas creatinine measurements give information on kidney’s health, tracking renal dialysis treatment, and monitor hospitalized patients that are on diuretics.[7]
For blood tests, clinical chemists must process the specimen to obtain plasma and serum before testing for targeted analytes. 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 obtained by centrifugation before clotting occurs.
Instruments
Most current medical laboratories now have highly automated analyzers to accommodate the high workload typical of a hospital laboratory, and accept samples for up to about 700 different kinds of tests.[9] Even the largest of laboratories rarely do all these tests themselves, and some must be referred to other labs. Tests performed are closely monitored and quality controlled.
Specialties
The large array of tests can be 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 electrophoresis, and manual testing methods.
↑ Bishop, Michael L.; Fody, Edward P.; Schoeff, Fody (2020). Clinical Chemistry: Principles, Techniques, Correlations. Enhanced Edition (8thed.). Burlington: Jones & Bartlett Learning. pp.76–77. ISBN9781284510140.
↑ Burtis, Carl A.; Bruns, David E. (2014). Tietz Fundamentals of Clinical Chemistry and Molecular Diagnostics (7thed.). Missouri: Elsevier. pp.674–709. ISBN978-1-4557-4165-6.
1 2 3 Rao, L. V.; Snyder, L. Michael (2020). Wallach's Interpretation of Diagnostic Tests: Pathways to Arriving at a Clinical Diagnosis (11thed.). Lippincott Williams & Wilkins. ISBN978-1-97-510558-7.
↑ MedlinePlus [Internet]. Bethesda (MD): National Library of Medicine (US); Calcium Blood Test; [updated 2022 Jun 02; cited 2023 April 05]; [about 3 screens]. Available from: https://medlineplus.gov/lab-tests/calcium-blood-test/
Nephrology is a specialty for both adult internal medicine and pediatric medicine that concerns the study of the kidneys, specifically normal kidney function and kidney disease, the preservation of kidney health, and the treatment of kidney disease, from diet and medication to renal replacement therapy. The word "renal" is an adjective meaning "relating to the kidneys", and its roots are French or late Latin. Whereas according to some opinions, "renal" and "nephro" should be replaced with "kidney" in scientific writings such as "kidney medicine" or "kidney replacement therapy", other experts have advocated preserving the use of renal and nephro as appropriate including in "nephrology" and "renal replacement therapy", respectively.
Albuminuria is a pathological condition wherein the protein albumin is abnormally present in the urine. It is a type of proteinuria. Albumin is a major plasma protein ; in healthy people, only trace amounts of it are present in urine, whereas larger amounts occur in the urine of patients with kidney disease. For a number of reasons, clinical terminology is changing to focus on albuminuria more than proteinuria.
Creatinine is a breakdown product of creatine phosphate from muscle and protein metabolism. It is released at a constant rate by the body.
Proteinuria is the presence of excess proteins in the urine. In healthy persons, urine contains very little protein, less than 150 mg/day; an excess is suggestive of illness. Excess protein in the urine often causes the urine to become foamy. Severe proteinuria can cause nephrotic syndrome in which there is worsening swelling of the body.
Serum is the fluid and solvent component of blood which does not play a role in clotting. It may be defined as blood plasma without the clotting factors, or as blood with all cells and clotting factors removed. Serum contains all proteins except clotting factors, including all electrolytes, antibodies, antigens, hormones; and any exogenous substances. Serum also does not contain all the formed elements of blood, which include blood cells, white blood cells, red blood cells (erythrocytes), and platelets.
An automated analyser is a medical laboratory instrument designed to measure various substances and other characteristics in a number of biological samples quickly, with minimal human assistance. These measured properties of blood and other fluids may be useful in the diagnosis of disease.
Uremia is the term for high levels of urea in the blood. Urea is one of the primary components of urine. It can be defined as an excess in the blood of amino acid and protein metabolism end products, such as urea and creatinine, which would be normally excreted in the urine. Uremic syndrome can be defined as the terminal clinical manifestation of kidney failure. It is the signs, symptoms and results from laboratory tests which result from inadequate excretory, regulatory, and endocrine function of the kidneys. Both uremia and uremic syndrome have been used interchangeably to denote a very high plasma urea concentration that is the result of renal failure. The former denotation will be used for the rest of the article.
Assessment of kidney function occurs in different ways, using the presence of symptoms and signs, as well as measurements using urine tests, blood tests, and medical imaging.
Tumor lysis syndrome (TLS) is a group of metabolic abnormalities that can occur as a complication from the treatment of cancer, where large amounts of tumor cells are killed off (lysed) from the treatment, releasing their contents into the bloodstream. This occurs most commonly after the treatment of lymphomas and leukemias and in particular when treating non-Hodgkin lymphoma, acute myeloid leukemia, and acute lymphoblastic leukemia. This is a potentially fatal complication and patients at increased risk for TLS should be closely monitored while receiving chemotherapy and should receive preventive measures and treatments as necessary. TLS can also occur on its own although this is less common.
A urine test is any medical test performed on a urine specimen. The analysis of urine is a valuable diagnostic tool because its composition reflects the functioning of many body systems, particularly the kidneys and urinary system, and specimens are easy to obtain. Common urine tests include the routine urinalysis, which examines the physical, chemical, and microscopic properties of the urine; urine drug screening; and urine pregnancy testing.
Serum albumin, often referred to simply as blood albumin, is an albumin found in vertebrate blood. Human serum albumin is encoded by the ALB gene. Other mammalian forms, such as bovine serum albumin, are chemically similar.
Gitelman syndrome (GS) is an autosomal recessive kidney tubule disorder characterized by low blood levels of potassium and magnesium, decreased excretion of calcium in the urine, and elevated blood pH. It is the most frequent hereditary salt-losing tubulopathy. Gitelman syndrome is caused by disease-causing variants on both alleles of the SLC12A3 gene. The SLC12A3 gene encodes the thiazide-sensitive sodium-chloride cotransporter, which can be found in the distal convoluted tubule of the kidney.
Nephritic syndrome is a syndrome comprising signs of nephritis, which is kidney disease involving inflammation. It often occurs in the glomerulus, where it is called glomerulonephritis. Glomerulonephritis is characterized by inflammation and thinning of the glomerular basement membrane and the occurrence of small pores in the podocytes of the glomerulus. These pores become large enough to permit both proteins and red blood cells to pass into the urine. By contrast, nephrotic syndrome is characterized by proteinuria and a constellation of other symptoms that specifically do not include hematuria. Nephritic syndrome, like nephrotic syndrome, may involve low level of albumin in the blood due to the protein albumin moving from the blood to the urine.
The anion gap is a value calculated from the results of multiple individual medical lab tests. It may be reported with the results of an electrolyte panel, which is often performed as part of a comprehensive metabolic panel.
Hypoalbuminemia is a medical sign in which the level of albumin in the blood is low. This can be due to decreased production in the liver, increased loss in the gastrointestinal tract or kidneys, increased use in the body, or abnormal distribution between body compartments. Patients often present with hypoalbuminemia as a result of another disease process such as malnutrition as a result of severe anorexia nervosa, sepsis, cirrhosis in the liver, nephrotic syndrome in the kidneys, or protein-losing enteropathy in the gastrointestinal tract. One of the roles of albumin is being the major driver of oncotic pressure in the bloodstream and the body. Thus, hypoalbuminemia leads to abnormal distributions of fluids within the body and its compartments. As a result, associated symptoms include edema in the lower legs, ascites in the abdomen, and effusions around internal organs. Laboratory tests aimed at assessing liver function diagnose hypoalbuminemia. Once identified, it is a poor prognostic indicator for patients with a variety of different diseases. Yet, it is only treated in very specific indications in patients with cirrhosis and nephrotic syndrome. Treatment instead focuses on the underlying cause of the hypoalbuminemia. Albumin is an acute negative phase respondent and not a reliable indicator of nutrition status.
Human serum albumin is the serum albumin found in human blood. It is the most abundant protein in human blood plasma; it constitutes about half of serum protein. It is produced in the liver. It is soluble in water, and it is monomeric.
Phosphate nephropathy or nephrocalcinosis is an adverse renal condition that arises with a formation of phosphate crystals within the kidney's tubules. This renal insufficiency is associated with the use of oral sodium phosphate (OSP) such as C.B. Fleet's Phospho soda and Salix's Visocol, for bowel cleansing prior to a colonoscopy.
A basic metabolic panel (BMP) is a blood test consisting of a set of seven or eight biochemical tests and is one of the most common lab tests ordered by health care providers. Outside the United States, blood tests made up of the majority of the same biochemical tests are called urea and electrolytes, or urea, electrolytes, creatinine, and are often referred to as 'kidney function tests' as they also include a calculated estimated glomerular filtration rate. The BMP provides key information regarding fluid and electrolyte status, kidney function, blood sugar levels, and response to various medications and other medical therapies. It is frequently employed as a screening tool during a physical exam.
The comprehensive metabolic panel, or chemical screen, is a panel of 14 blood tests that serves as an initial broad medical screening tool. The CMP provides a rough check of kidney function, liver function, diabetic and parathyroid status, and electrolyte and fluid balance, but this type of screening has its limitations. Abnormal values from a CMP are often the result of false positives and thus the CMP may need to be repeated, requiring a second blood drawing procedure and possibly additional expense for the patient, even though no disease is present. This test is also known as SMA12+2 test.
The Jaffe reaction is a colorimetric method used in clinical chemistry to determine creatinine levels in blood and urine. In 1886, Max Jaffe (1841–1911) wrote about its basic principles in the paper Über den Niederschlag, welchen Pikrinsäure in normalem Harn erzeugt und über eine neue Reaction des Kreatinins in which he described the properties of creatinine and picric acid in an alkaline solution. The color change that occurred was directly proportional to the concentration of creatinine, however he also noted that several other organic compounds induced similar reactions. In the early 20th century, Otto Folin adapted Jaffe's research into a clinical procedure. The Jaffe reaction, despite its nonspecificity for creatinine, is still widely employed as the method of choice for creatinine testing due to its speed, adaptability in automated analysis, and cost-effectiveness, and is the oldest methodology continued to be used in the medical laboratory. It is this nonspecificity that has motivated the development of new reference methods for creatinine analysis into the 21st century.
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