Markers for Liver Function Liver function tests also called hepatic panels, are blood tests used to monitor liver function and damage. These tests provide insights into several aspects of liver health, notably. the liver’s ability to synthesize enzymes and proteins, the liver’s ability to process bilirubin and secrete bile, and the extent of liver damage.
Abnormal liver function test results do not always indicate liver disease. Some abnormalities are transient; or they may result from different, non-hepatic causes. The synthetic function of the liver can be assessed based on its ability to produce plasma proteins, such as albumin and coagulation factors. Serum albumin levels FALL with all liver diseases.
However, low serum albumin may also result from low protein intake, malabsorption, or abnormal loss of proteins in urine. Prothrombin time, PT, or pro time test, measures
the time the blood takes to clot. A decline in liver function leads to fewer coagulation
factors produced and delays coagulation time. However, a high PT may also indicate a bleeding disorder, vitamin K deficiency, or the use of blood-thinning medications, such as warfarin.
When liver cells are injured, their content, including liver enzymes, is leaked into the
bloodstream. The levels of these enzymes can be measured to assess the extent of liver damage.
Two enzymes are usually included in a hepatic panel: aspartate transaminase,
AST and alanine aminotransaminase, ALT; both enzymes are involved in protein metabolism in the liver.
AST and ALT are present at high concentrations in the liver, but they are also found in a number of other tissues. ALT is more sensitive and specific for liver damage than AST.
AST and ALT elevations may also result from non-hepatic causes.
Bilirubin is a water-insoluble product of normal heme breakdown. Bilirubin is transported to the liver loosely bound to albumin. The liver converts bilirubin into a water-soluble form to be secreted into bile. Accumulation of bilirubin in the blood indicates problems with biliary function. High levels of bilirubin give the skin and the whites of the eyes a yellowish color known as jaundice.
Besides bilirubin, two enzymes named alkaline phosphatase (ALP), and gamma-glutamyltransferase (GGT) are measured for biliary function, Both enzymes are found in the tiny bile ducts, called canaliculi, of the liver; but they are also present in several other tissues. Damage to the biliary tract releases these enzymes into the bloodstream. Elevated GGT is more specific for biliary disease compared to ALP. ALP elevations may also be due to a number of non-hepatic causes.
Markers for Liver Function
1. Albumin (Mb)
Albumin is a protein produced exclusively by the liver that can be measured easily and cheaply and easily. It is the primary component of total protein; the remaining fraction is known as globulin (including the immunoglobulins). Chronic liver disease, such as cirrhosis, causes a decrease in albumin levels. It is also reduced in nephrotic syndrome, where it is excreted in the urine. Hypoathuminaernia can also be caused by poor nutrition or impaired protein catabolism, such as in Menetrier’s disease. Albumin has a half-life of approximately 20 days. Albumin is not thought to be a particularly useful indicator of liver synthetic function; coagulation factors are far more sensitive.
2. Aspartate transaminase (AST)
Aspartate transaminase (AST), also known as Serum Glutamic Oxaloacetic Transaminase (SGOT) or aspartate aminotransferase (ASAT), is another enzyme associated with liver parenchymal cells like ALT. It is increased in acute liver damage, but it is also found in red blood cells, cardiac, heart, and skeletal muscle, so it is not specific to the liver. The AST/ALT ratio can help distinguish between different types of liver damage. Elevated AST levels are not always associated with liver damage, and AST has been used as a cardiac marker. AST increases in the case of liver disease, myocardial infarction, and muscle disease.
3. Alkaline phosphatase (ALP)
Alkaline phosphatase (ALP) is an enzyme found in the cells that line the liver’s biliary ducts. ALP levels in plasma will rise in the presence of a large bile duct obstruction, intrahepatic cholestasis, or liver infiltrative disease. ALP is also found in bone and placental tissue, so it is more prevalent in growing children (due to bone remodeling) and elderly patients with Paget’s disease.
4. Total bilirubin Reference range (0.2-1.2 mg/D1)
Bilirubin is a byproduct of heme (a part of hemoglobin in red blood cells). The liver is in charge of removing bilirubin from the bloodstream.
It achieves this through the following mechanism: bilirubin is taken up by hepatocytes, conjugated (modified to make it water-soluble), and secreted into bile, which is then excreted into the intestine.
Increased total bilirubin causes jaundice and can indicate a number of problems:
Prehepatic: increased bilirubin production, which can be caused by a variety of factors such as hemolytic anemias and internal hemorrhage.
Hepatic: Liver problems manifested as deficiencies in bilirubin metabolism (reduced hepatocyte uptake, impaired bilirubin conjugation, and reduced bilirubin secretion by hepatocytes). Cirrhosis and viral hepatitis are two such diseases.
Posthcpatic: ObstrPosthcpatic: Obstruction of the bile ducts, revealed as bilirubin excretion deficiencies. (Obstruction It can be found in the liver or in the bile duct.
Direct bilirubin (Conjugated Bilirubin) Reference range (0.1-0.4 mg/d L):
The presence of direct bilirubin narrows the diagnosis even further. If direct (i.e. conjugated) bilirubin levels are normal, the problem is an excess of unconjugated bilirubin, and the problem is located upstream of bilirubin excretion. Hemolysis, viral hepatitis, or cirrhosis are all possibilities.
If direct bilirubin levels are high, this indicates that the liver is conjugating bilirubin normally but is unable to excrete it. Gallstones or cancer-related bile duct obstruction should be suspected.
5. Gamma-glutamyl transpeptidase (GGT)
Gamma-glutamyl transpeptidase (GGT) may be elevated with even minor, subclinical levels of liver dysfunction, despite being more specific to the liver and a more sensitive marker for cholestatic damage than ALP. It can also help in determining the cause of an isolated rise in ALP. (In chronic alcohol toxicity, GGT levels rise.)
6. 5′ nucleotidase (5’NTD)
Another test specific for cholestasis or damage to the intra or extrahepatic biliary system, 5′ nucleotidase, is used in some laboratories as a substitute for GGT to determine whether an elevated ALP is of binary or extra-biliary origin.
Marker for determination of Kidney function
GFR-Inulin, Manitol, Creatinine, Cystatin-C, hippuric acid GFR-120-130.
Liver Functional Test
1. Test for serum bilirubin.
This test determines the amount of bilirubin in the blood. Bilirubin is produced by the liver and excreted in bile. Elevated bilirubin levels may indicate a bile flow obstruction or a problem with bile processing by the liver.
2. Test for serum albumin.
This test measures the level of albumin (a protein found in the blood) and may aid in the diagnosis of liver disease. Low albumin levels may indicate that the liver is not working properly.
3. The prothrombin time (PT) test
PT test is formally known as the international normalized ratio (INR). This test determines the time it takes for blood to clot. Vitamin K is Responsible for blood clotting and is also a Protein produced by the liver. Prolonged clotting may be caused by liver disease or a lack of specific clotting factors.
Types of Liver Disease
The following Disease identified by the FLFT test
- Viral Hepatitis A, B,C,D,E
- Cirrhosis/Liver Failure
- Hepatic Encephalopathy
- Ascites Fluid in Belly
- Tumors/ Cancers
Liver Function Biochemical Test Report:
|Bilirubin (Total)||mg/dl||0.33||0 to 0.4|
|Bilirubin (Direct)||mg/dl||0.15||0 to 0.1|
|Bilirubin (indirect)||mg/dl||0.18||0 to 0.3|
|SGOT (AST)||U/L||55.2||9 to 49|
|SGPT (ALT)||U/L||25.9||8 to 57|
|Alkaline Phosphate||U/L||183.4||10 to 100|
|Total Protein||g/dl||5.6||5.5 to 7.5|
|Albumin||g/dl||2.7||2.6 to 4|
|Globulin||g/dl||2.9||2.1 to 3.7|
|A/G Ratio||0.9:1||0.5 to 2.2|