Clinical chemistry

Clinical chemistry (also known as chemical pathology) 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 in the UK these are usually grouped under hematology, but in many countries these specialties along with immunology and microbiology are grouped under laboratory medicine.

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. Plasma is essentially the same as serum, but is obtained by centrifuging the blood without clotting. Plasma contains all of the clotting factors, including fibrinogen.

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 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 - the study of hormones
 * Immunology - the study of the immune system and antibodies
 * Pharmacology or Toxicology - the study of drugs

Clinical Chemistry Tests
Common chemical pathology tests include:

-Electrolytes
 * Sodium;
 * Potassium;
 * Chloride;
 * Bicarbonate;

-Renal (Kidney) Function Tests
 * Creatinine;
 * Blood urea nitrogen;

-Liver Function Tests
 * Total protein (serum);
 * Albumin;
 * Globulins;
 * A/G ratio (albumin/globulin)
 * Protein electrophoresis
 * Urine protein
 * Bilirubin; direct; indirect; total
 * Aspartate transaminase (AST);
 * Alanine transaminase (ALT);
 * Gamma-glutamyl transpeptidase (GGT);
 * Alkaline phosphatase (ALP);

-Cardiac Markers
 * Troponin
 * Myoglobin
 * CK-MB
 * B-type natriuretic peptide (BNP)

-Minerals
 * Calcium;
 * Magnesium;
 * Phosphate;
 * Potassium;

-Blood Disorders
 * Iron;
 * Transferrin;
 * TIBC
 * Vitamin B12
 * Folic acid

-Miscellaneous
 * Glucose;
 * C-reactive protein;
 * Glycated hemoglobin (HbA1c);
 * Uric acid;
 * Arterial blood gases ($$ [H^+], P_{{\mathrm{CO}}_2}, P_{{\mathrm{O}}_2} $$);
 * Adrenocorticotropic hormone (ACTH);
 * Toxicological screening and forensic toxicology (drugs and toxins);
 * Neuron specific enolase (NSE);
 * fecal occult blood test (FOBT);

Panel tests
A set of commonly ordered tests are combined into a panel:
 * Basic metabolic panel (BMP) - 7 tests - sodium, potassium, chloride, bicarbonate, blood urea nitrogen (BUN), creatinine, glucose
 * Comprehensive metabolic panel (CMP) - 14 tests - above BMP plus calcium, total protein, albumin, alkaline phosphatase (ALP), alanine amino transferase (ALT), aspartate amino transferase (AST), bilirubin