Thu. Jun 8th, 2023
Liver Functions - Complete Guide in Digestive System

The liver is a vital organ in the body, performing all necessary bodily functions. Unfortunately, people often fail to realize the importance of a healthy liver functions.

Anatomically speaking, the liver is the largest, solid gland in the body, weighing around 1.8 kgs in males and about 1.3 kgs in females. It is situated beneath the rib cage in the right upper abdomen.

This is a comprehensive guide to how a liver function blood test can help you maintain a healthy liver by identifying concerns ahead of time.

Key Points to Note 

  • The liver is the largest organ in the human body
  • It extends from the right fifth rib cage to the lower border of the rib cage
  • It filters all of the blood and breaks down poisonous substances into smaller particles
  • It comprises four lobes, each consisting of eight small sections and thousands of lobules
  • The organ produces a by-product called bile, a fluid that carries away waste and digests fat molecules

All about Liver Functions 

Being an essential organ, the liver performs over 500 vital functions in the human body. Here are some of the most crucial liver functions you need to know:

  • Produces albumin: The albumin protein helps to keep blood from leaking into surrounding tissues. Also, it carries important hormones, enzymes and vitamins through the body.
  • Produces bile: Bile is vital in the digestion and absorption of fats in the small intestine.
  • Regulates amino acids: Protein production depends solely on amnion acids. It is the duty of the liver to make sure the amino acids in the bloodstream remain in normal condition.
  • Regulates clotting: It creates blood clotting coagulants.
  • Filters blood particles: Blood leaving the stomach and intestines washes away toxins while passing through the liver.
  • Prevent infections: The liver functions helps remove bacteria from the blood as part of the filtering process.
  • Stores essential vitamins & minerals: It stores Vitamins A, D, E, K, B12, and iron & copper.
  • Processes glucose: It helps regulate glucose levels in the blood and stores it as glycogen.

Liver Disorder Symptoms

Not everyone experiences the same symptoms. Having a liver disease does not necessarily mean that you will have every symptom associated with it.

This makes it difficult to diagnose a liver disease in the first place. However, when patients exhibit symptoms, they may include:

  • Jaundice
  • Abdominal pain (right upper quadrant)
  • Intense itching or thinning skin
  • Anorexia, weight loss & muscle waste
  • Clay-coloured stools
  • Highly pigmented urine
  • Trouble sleeping
  • Fatigue
  • Compromised consciousness

If you have any of the symptoms, make sure you discuss your concerns with a private doctor.

What Is LFT Blood Test?

LFT stands for Liver Function Test. It is a group of blood tests to measure a) substances produced by the liver and b) substances released from a damaged liver. It is, essentially, a screening tool to determine the condition of the liver at any given time. The tool measures the levels of proteins in the bloodstream. Doctors recommend a liver function test to find out any abnormalities in the liver functions. It also helps to gauge how severe is the damage. Apart from this, your doctor may also need this test to check the outcomes of treatment.

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Taking a Liver Functions Test

It is a simple and straightforward test that assists doctors to understand the condition of the liver. The test uses a blood sample, which is then sent to the laboratory for further study.

Thanks to the advancements in technology, the liver functions test needs a very little amount of blood. Also, you can conduct a home liver functions test using a finger-prick blood sample.

Why Take an LFT Blood Test?

Liver Functions Tests do not always identify the underlying cause of a condition. However, abnormal results enable your doctor to work out a suitable treatment plan. By combining the clinical history and physical examination data along with the test results, your doctor will be able to make a correct diagnosis.

You should take the test for the following reasons as well:

  • If you experience any symptoms of a liver disorder
  • Your doctor wants to check for damage from liver infections
  • If you have gallbladder disease
  • If you consume alcohol in excessive amounts
  • If you have high blood pressure, diabetes or anaemia
  • Your doctor wants to monitor your liver disease and ensure the treatment is working

What Does It Measure?

In an LFT panel, three major groups of biomarkers are tested. The tests include:

1. Bilirubin test

  • Serum bilirubin

2. Liver protein test

  • Albumin
  • Globulin
  • Albumin to globulin ratio
  • Prothrombin time

3. Liver enzyme test

  • Alkaline Phosphatase test (ALP)
  • Alanine Aminotransferase test (ALT)
  • Aspartate Aminotransferase test (AST)
  • Gamma-Glutamyl Transferase test (GGT)

Bilirubin testing

A bilirubin test helps to check the levels of bilirubin in multiple forms, including:

  • Total bilirubin – the total amount of conjugated and unconjugated bilirubin
  • Conjugated bilirubin – the water-soluble fraction of total bilirubin
  • Unconjugated bilirubin – the difference between the total and the conjugated bilirubin

The normal levels of total bilirubin are 0.2 – 0.8 mg/dl. Conjugated and unconjugated bilirubin levels must be between 0.1 to 0.4 mg/dl and 0.2 to 0.7 mg/dl respectively.

Serum albumin

The liver functions is responsible for synthesizing a protein i.e., albumin. The usual level of albumin is between 3.5 to 5 g/dL. In acute viral hepatitis, obstructive jaundice or drug-related hepatotoxicity, the levels of albumin may remain normal. In any chronic condition, the levels decrease.

A decreased level of album is also associated with protein malnutrition, chronic protein-losing enteropathies, and nephrotic syndrome.

Serum globulin

Serum globulins are present in various different forms ranging from immunoglobulins to enzymes. Normal levels are 2.5 to 3.5 g/dL. High levels of serum globulins are seen in autoimmune hepatitis, alcoholic liver disease, chronic hepatitis, and cirrhosis, among others.

Prothrombin time

The liver function synthesizes another protein i.e., prothrombin. It is responsible for blood clotting and is a marker of normal liver function. The protein indicates the current state of liver functions. The normal prothrombin time is 10 to 14 seconds.

The time increases when the liver loses more than 80% of its capacity. Conditions, when prothrombin time decreases, include vitamin K deficiency, ingestion of certain drugs, and disseminated intravascular coagulation, among others.

Alkaline Phosphatase test

The alkaline Phosphatase enzyme is also present in the liver and bone tissue. The enzyme performs lipid transport in the intestine and helps in the calcification of bone.

It is a marker of liver function. In an event of liver damage or injury, the enzyme spills out into the bloodstream, causing increased ALP levels. The normal levels of ALP are between 41 and 133 IU/L.5.

Alanine Aminotransferase test

Alanine Aminotransferase (ALT) is present in the muscle, heart, and kidney with a greater concentration being present in the liver. The normal levels of this enzyme are between 7 and 56 IU/L2.

Minor ALT levels (50 to 100 IU/L) are associated with conditions such as non-alcoholic steatohepatitis, cirrhosis, and hepatitis C. Alcoholic hepatitis causes moderate elevation of ALT i.e., 100 to 300 IU/L.

Very high levels (300 to 1000 IU/L) of ALT result in acute hepatitis, toxin-induced liver damage, and ischemic liver injury.

Aspartate Aminotransferase test

Aspartate Aminotransferase (AST) is a marker of liver cell damage. The normal range of AST hovers between 0 to 35 IU/L2. Higher serum levels occur due to conditions such as liver cirrhosis, hepatocellular carcinoma, chronic hepatitis, and asymptomatic pregnant patient with pre-eclampsia.

Gamma Glutamyl Transferase test or GGT

GGT is widely present in the body tissues such as liver cells. To assess abnormalities in the liver, this test is done. The normal levels of GGT are 9 to 85 U/L.5. AST levels increase in conditions such as prostate cancer, and infective hepatitis.

Some non-hepatic causes may cause the levels to increase, which include acute pancreatitis, obesity, uncomplicated diabetes mellitus, hyperthyroidism, and myocardial infarction. The levels may also increase due to the use of drugs such as Phenytoin, Paracetamol, Phenobarbitone, and other antidepressant drugs. This is a highly-sensitive indicator of alcohol abuse.

To Wrap up

Apart from the tests mentioned here, there are other tests that help assess the functions of the liver. While they are not common, doctors may need those under specific circumstances. They include NTP or Nucleotidase, Ceruloplasmin, α- fetoprotein (AFP), among others.

Your liver plays a vital role in performing various important boldly functions. It is your responsibility to keep it healthy at all times. Make sure you consider doing a private liver function test as soon as you experience any of the symptoms.

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