Custom Search
|
blood, more explained ...
Gamma-glutamyl transferase (GGT or GGTP, or Gamma-GT)
is primarily a liver enzyme.
Function: It is involved in the transfer of amino acids across the cellular membrane.
It is also involved in glutathione metabolism by transferring the glutamyl moiety to a variety of acceptor molecules including water,
certain L-amino acids and peptides. Leaving the cysteine product to preserve intracellular homeostasis of oxidative stress.
It is involved in leukotriene metabolism.
GGT is found on the cell surface on all cells, with particularly high concentrations in the liver, bile ducts, and kidney.
The enzyme is also present in other tissues, such as the epididymis.
Aspartate transaminase
(AST, ASAT) also called serum glutamic oxaloacetic transaminase (SGOT) or aspartate aminotransferase (ASAT/AAT) is similar to
alanine transaminase (ALT) in that it is another enzyme associated with liver parenchymal cells.
Function: It facilitates the conversion of aspartate and alpha-ketoglutarate to oxaloacetate and glutamate, and vice-versa.
Isozymes
Two isoenzymes are present in humans. They have high similarity.
GOT1, the cytosolic isoenzyme derives mainly from red blood cells and heart.
GOT2, the mitochondrial isoenzyme is predominantly present in liver.
Clinical significance
It is raised in acute liver damage. It is also present in red blood cells and cardiac muscle, skeletal muscle,
and kidney and brain tissue, and may be elevated due to damage to those sources as well.
AST was defined as a biochemical marker for the diagnosis of acute myocardial infarction in 1954.
However the use of AST for such a diagnosis is now redundant and has been superseded by the cardiac troponins.
AST (SGOT) is commonly measured clinically as a part of diagnostic liver function tests, to determine liver health.
Alanine transaminase or ALT
is a transaminase enzyme.
It is also called serum glutamic pyruvic transaminase (SGPT) or alanine aminotransferase (ALAT).
ALT is found in serum and in various bodily tissues, but is most commonly associated with the liver.
C-reactive protein
(CRP) is a protein found in the blood in response to inflammation (an acute-phase protein).
CRP is produced by the liver and by fat cells (adipocytes). It is a member of the pentraxin family of proteins.
It is not related to C-peptide or protein C.
History and nomenclature
C-reactive protein was originally discovered by Tillett and Francis in 1930 as a substance in the serum of patients with acute
inflammation that reacted with the C polysaccharide of pneumococcus. Initially it was thought that CRP might be a pathogenic secretion,
as it was elevated in people with a variety of illnesses, including carcinomas.
Discovery of hepatic synthesis and secretion of CRP closed that debate. It is thought to bind to phosphocholine,
thus initiating recognition and phagocytosis of damaged cells.
Alkaline phosphatase
(ALP) Alkaline phosphatase (ALP) is an enzyme in the cells lining the biliary ducts of the liver.
ALP levels in plasma will rise with large bile duct obstruction, intrahepatic cholestasis or infiltrative diseases of the liver.
ALP is also present in bone and placental tissue, so it is higher in growing children (as their bones are being remodelled)
and elderly patients with Paget's disease.
Total bilirubin
(TBIL) Bilirubin is a breakdown product of heme (a part of haemoglobin in red blood cells).
The liver is responsible for clearing the blood of bilirubin. It does this by the following mechanism: bilirubin is taken up into hepatocytes,
conjugated (modified to make it water-soluble), and secreted into the bile, which is excreted into the intestine.
Increased total bilirubin causes jaundice, and can signal a number of problems:
1. Prehepatic: Increased bilirubin production. This can be due to a number of causes,
including hemolytic anemias and internal hemorrhage.
2. Hepatic: Problems with the liver, which are reflected as deficiencies in bilirubin metabolism (e.g. reduced hepatocyte uptake,
impaired conjugation of bilirubin, and reduced hepatocyte secretion of bilirubin).
Some examples would be cirrhosis and viral hepatitis.
3. Posthepatic: Obstruction of the bile ducts, reflected as deficiencies in bilirubin excretion.
(Obstruction can be located either within the liver or in the bile duct.)
The erythrocyte sedimentation rate (ESR)
also called a sedimentation rate or Biernacki Reaction, is the rate at which red blood cells precipitate in a period of 1 hour.
It is a common haematology test which is a non-specific measure of inflammation.
To perform the test, anticoagulated blood is placed in an upright tube,
known as a Westergren tube and the rate at which the red blood cells fall is measured and reported in mm/h.
Since the introduction of automated analyzers into the clinical laboratory, the ESR test has been automatically performed.
The ESR is governed by the balance between pro-sedimentation factors, mainly fibrinogen, and those factors resisting sedimentation,
namely the negative charge of the erythrocytes (zeta potential). When an inflammatory process is present,
the high proportion of fibrinogen in the blood causes red blood cells to stick to each other.
The red cells form stacks called 'rouleaux' which settle faster.
Rouleaux formation can also occur in association with some lymphoproliferative disorders in which one or more
immunoglobulins are secreted in high amounts. Rouleaux formation can, however, be a normal physiological finding in horses,
cats and pigs.
The ESR is increased by any cause or focus of inflammation. The ESR is decreased in sickle cell anemia,
polycythemia, and congestive heart failure. The basal ESR is slightly higher in females.
White blood cells, or leukocytes
(also spelled "leucocytes"), are cells of the immune system defending the body against both infectious disease and foreign materials.
Five different and diverse types of leukocytes exist, but they are all produced and derived from a multipotent cell in the bone marrow
known as a hematopoietic stem cell. Leukocytes are found throughout the body, including the blood and lymphatic system.
Thrombocytes are cells that play a key role in blood clotting. In mammals, thrombocytes are anucleated cell fragments called platelets. Nucleated thrombocytes of nonmammalian vertebrates differ from the mammalian thrombocytes not only in having a nucleus and thus resembling B lymphocytes, but also these nucleated thrombocytes do not aggregate in response to ADP, serotonin and adrenaline (they do aggregate with thrombin, of course.).
all of the above items are monthly tested when Tysabri is used
The information about this subject is edited,
and based on this article
editor: H.m.Hanse copyright in accordance with the GNU licence