Chemical pathology

Chemical pathology (also known as clinical biochemistry or clinical chemistry) is the area of pathology that is generally 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. Subsequently other techniques were applied including the use and measurement of enzyme activities, spectrophotometry, electrophoresis and immunoassay.

Most current laboratories are now highly automated and use assays that are closely monitored and quality controlled.

Tests that require examination and measurement of the cells of blood, as well as blood clotting studies, are not included as these are usually grouped under haematology.

All biochemical tests come under chemical pathology. These are usually performed on serum, (the yellow watery part of blood that is left after the blood has been allowed to clot and all blood cells have been removed. This is most easily done by centrifugation which packs the more dense blood cells and platelets to the bottom of the centrifuge tube, leaving the liquid serum fraction resting above the packed cells).

A large laboratory will accept up to about 700 tests. Even the largest of laboratories rarely does all these tests themselves and some need to be referred to other labs.

This large array of tests can be further sub-categorised into sub- specialities of:

• General or routine chemistry
• Endocrinology to do with hormones
• Immunology to do with the study of the immune system and antibodies
• Pharmacology or Toxicology to do with the study of drugs

Common Chemical Pathology tests are listed below

Sodium	Potassium	Chloride
Bicarbonate	Urea	Creatinine
Calcium	Phosphate	Albumin
Bilirubin	AST	ALT
GGT	Alkaline phosphatase	Magnesium
Osmolality	Urate	Iron
Transferrin	Total protein	Globulins
Glucose	C-reactive protein	HbA1c

See also

• Reference ranges for common blood tests