Clinical chemistry

Clinical chemistry analyzers are rapidly providing greater automation to the clinical laboratory.

Clinical chemistry (sometimes referred to as chemical pathology) is the area of clinical pathology that is generally concerned with analysis of bodily fluids. The discipline originated in the late nineteenth 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.

Today clinical laboratories are now highly automated to accommodate the high workload typical of a hospital laboratory or reference laboratory. A large clinical 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:

• general or routine chemistry - use of common blood chemistry tests (e.g. liver and kidney function tests)
• special chemistry - use of elaborate techniques such as protein electrophoresis and manual testing methods
• clinical endocrinology - study of hormones and diagnosis of endocrine disorders
• toxicology - study of the adverse effects of drugs of abuse and other chemicals
• therapeutic drug monitoring - measurement of therapeutic medication levels to optimize dosage
• urinalysis - chemical analysis of urine for a wide array of diseases
• fecal analysis - detection of gastrointestinal disorders

Testing

Common blood tests performed in clinical chemistry include:

• complete blood count (CBC): measures red and white blood cells, platelets, hemoglobin, hematocrit, and mean corpuscular volume to help detect blood diseases and disorders
• blood chemistry tests: measures blood glucose, calcium, electrolyte, and kidney function over a series of tests called a basic metabolic panel (see below) to provide information about your muscles, bones, and organs
• blood enzyme tests: measures aspects of blood like troponin and creatine kinase to ensure enzymes are properly controlling chemical reactions in your body
• blood tests to assess heart disease risk: LDL cholesterol, HDL cholesterol, total cholesterol, and triglycerides over a series of tests called a lipoprotein panel (see below)
• blood clotting tests: measures proteins in your blood that affect the blood clotting process over a series of tests called a coagulation panel (see below)

Common urine tests performed in clinical chemistry include:

• standard tests: analyses appearance, gravity, and pH as well as protein, glucose, and ketone levels for diagnosing diseases and conditions like diabetes, hypertension, liver failure, and renal deficiency
• microscopic tests: analyses for red and white blood cells, casts, crystals, and bacteria for diagnosing diseases and conditions like cystitis, urinary tract infection, hypercalcemia, and vaginitis

Panel testing

A set of commonly ordered tests are typically combined into what is called a panel. Examples include:

• basic metabolic panel (BMP): Eight tests - sodium, potassium, chloride, bicarbonate, blood urea nitrogen (BUN), creatinine, glucose, and calcium
• comprehensive metabolic panel (CMP): 14 tests - the BMP plus total protein, albumin, alkaline phosphatase (ALP), alanine amino transferase (ALT), aspartate amino transferase (AST), and bilirubin
• lipoprotein or lipid panel: three tests - low-density lipoprotein (LDL), high-density lipoprotein (HDL), and triglycerides (total cholesterol is calculated from these tests)
• coagulation panel: three to four tests - partial thromboplastin time (PTT), activated partial thromboplastin time (APTT), prothrombin time with international normalized ratio (PT/INR), and platelet count

See also

• Clinical laboratory
• Clinical pathology

Notes

Some elements of this article are reused from the Wikipedia article.