Total Protein

Serum protein is comprised of albuminS and globulin, either bound or act- ing as carrier proteins. Plasma proteins are mostly synthesized in the liver, except for immunoglobulins, which are synthesized in the lymphoreticular system. They are a source of nutrition and a buffer system. Increased levels of total serum protein occur in conditions like dehydration, haemoconcentration states due to fluid loss. Decreased levels are associated with insufficient nutritional intake, severe liver disease, renal disease and other conditions.

Use of Test: Diagnosis and monitoring of hypergammaglobulinaemia and hypogammaglobulinaemia, protein losing states and malnutrition. Used in conjunction with albumin to calculate globulin.

Albumin

Most serum albumin is produced by the liver. It contributes towards maintaining the colloid oncotic pressure of plasma. Albumin also acts as a transport protein for some drugs and substances such as fatty acids, calcium, unconjugated bilirubin, thyroxine and urate. Increased levels  may be seen with dehydration. Decreased levels may be associated with conditions such as overhydration, chronic liver disease and protein losing disorders.

Use of Test: Evaluation of nutritional status, protein losing disorders, liver disease, dehydration.

Bilirubin (Total)

Bilirubin is formed from the breakdown of haemoglobin in red blood cells by reticuloendothelial cells mainly in the spleen, liver and bone marrow. Total bilirubin comprises unconjugated, conjugated and delta bilirubins. Bilirubin is removed from the body by the liver, which excretes it into the bile. Elevated serum levels occur if the liver is unable to excrete the normal amount of bilirubin produced or if there is an excessive destruction of red blood cells. Jaundice, a condition with visible yellow colouration of the skin, sclera and mucous membrane is characterised by high levels of bilirubin in the blood.

Use of Test: Investigation and monitoring of hepatobiliary disease and haemolysis.

检查的作用：肝胆疾病和溶血现象的检查与诊断。

Alkaline Phosphatase (ALP)

Alkaline phosphatase is a group of closely related enzymes found in many tissues, with highest concentrations in liver and biliary tract epithelium, bone, intestinal mucosa and placenta. ALP activity is increased in many conditions, the two principal categories being liver and bone diseases.

Use of Test: Investigation of hepatobiliary or bone disease.

Aspartate Aminotransferase (AST/SGOT)

AST is an enzyme found in several organs and tissues, including liver, heart, skeletal muscle, kidney, brain, pancreas, spleen, and lungs. The enzyme is released into the circulation following the injury or death of cells. Increased levels are found with hepatocellular disease, as well as cardiac and skeletal muscle diseases.

Use of Test: Detection and monitoring of liver cell damage.

Alanine Aminotransferase (ALT/SGPT)

ALT is an enzyme found predominantly in liver but with lower concentrations in the kidney, heart and skeletal muscle. In general, most ALT elevations are due to liver disease. ALT is more specific for hepatocellular damage than AST.

Use of Test: Detection and monitoring of liver cell damage.

Gamma Glutamyltransferase (GGT)

GGT is an enzyme located mainly in the liver, kidney, biliary tract epithelium, intestine, heart, brain, pancreas and spleen. GGT is affected by both acute liver damage and biliary tract obstruction. The test is used to determine liver cell dysfunction and to detect alcohol-induced liver disease. Pancreatitis and prostatitis may also be associated with in- creased levels.

Use of test: Evaluation of liver disease.

Lactate Dehydrogenase (LDH)

LDH is an intracellular enzyme found in heart, skeletal muscle, red blood cells, brain, lung, liver and kidney. Increases in value usually indicate cellular death and leakage of the enzyme from cells. A considerable number of conditions can elevate LDH level.

Use of Test: A non-specific indicator of disease. Of limited value in supporting the diagnosis of myocardial infarction when testing is performed >48 hours after the onset of chest pain. Maybe useful occasionally in the assessment of patients with liver disease or malignancy (especially lymphoma, seminoma, hepatic metastases); anaemia when haemolysis or ineffective erythropoeisis is suspected.