• Published on: Sep 15, 2021
  • 5 minute read
  • By: Dr Rakesh Rai

Everything About Liver Function Tests- Purpose & Significance

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Everything About Liver Function Tests- Purpose & Significance

Liver function tests are medical laboratory tests that measure the number of various substances in the blood that are released into your blood by liver cells or made by your liver. These substances are often called "liver enzymes" because they are enzymes that are produced exclusively by the liver to help regulate metabolism for processing chemicals, nutrients, and drugs.

A high level of any one of these may suggest an abnormal situation involving your liver. The most common symptoms associated with a problem involving your liver include nausea, vomiting, yellowing skin color (jaundice), fever, and abdominal discomfort such as pain on gentle pressing around about halfway down on the right side of the abdomen.

A liver function test is a blood test that evaluates an individual's liver function or sees if there may be a problem in this organ. Liver functions including leukocyte count, alkaline phosphatase, ALT/AST enzymes, and bilirubin levels are measured with results interpreted by physicians who then advise treatment options to relieve pain or reduce the risk of liver disease. If the level of these agents is elevated then the physician will typically recommend further diagnostics such as antibody testing for hepatitis B and C infections, ultrasounds, and biopsies.

Liver function tests are a series of blood tests used to evaluate liver function. Tests may include the following:

  • Inclusion of serum albumin or total proteins as variables in the SMA12 test
  • Albumin fractional catabolic rate (ACR) and erythrocyte sedimentation rate (ESR) measurements, which can be used as a surrogate marker for changes in hepatocellular activity
  • Visible change is indicative that hepatocytes have been damaged or destroyed, an indicator that liver disease is present.
  • Fractional synthetic rate of albumin synthesis calculated from measurements of serum creatinine and urinary urea nitrogen providing information about hepatocyte intracellular mass status with decreased album

The most common of these are aminotransferases ALT and AST. These enzymes are released into the bloodstream in excessive amounts by the cells that line the bile ducts that carry bile from the liver - where it gets made - to where it gets used up in digestion ??i.e., all over your body, not just in your liver but also near your kidneys) when there's any sort of problem with those cells or with damage done to them because of some other hurtful event.

In the context of a medical lab test, a liver function test is anyone that has to do with the liver. Serum bilirubin, alanine aminotransferase (ALT), aspartate aminotransferase (AST), and alkaline phosphatase are common ones. A veterinarian could use ultrasound as well as biochemistry analysis. These tests show how well your liver is performing its duty to remove toxins from your body and to make bile for those toxins.  Liver function tests are conducted to assess the liver's ability to convert inactive substances in your blood to active ones.

Alanine aminotransferase (ALT/SGPT): tests what process - amino acid, carbohydrate, or fat - your liver is having trouble breaking down to store sugar for later use indigestion. This test will only show what type of enzyme the liver has difficulty processing at this time, so if this is normal but an alkaline phosphatase test comes back abnormal, this means there may be a different illness affecting the liver.

The test can measure certain chemicals that are released because of metabolism and excreted from the body in urine, such as albumin.

The most common indicators measured by blood-based liver function tests include GGT, ALP, total bilirubin / conjugated/unconjugated bilirubin, ALT and ASAT.

A group of enzymes found in healthy livers called GOT (gamma-glutamyl transpeptidase) and GPT (gamma-glutamyltransferase) can also be measured to determine damage to liver cells.

Liver Function Tests (LFTs) are a group of tests that measure the levels and function of various substances in the blood leave before digestion and within the liver. These include enzymes and proteins made by the liver; cholesterol, copper, iron, calcium, sodium, potassium; bilirubin level; albumin levels. The LFTs can be used to help diagnose many diseases such as viral hepatitis or alcoholic liver disease.

A history would normally prompt additional testing such as abdominal imaging for gallstones or metabolic abnormalities like cirrhosis caused by alcohol consumption. Kidney function should be tested because high-protein diets may cause kidney problems too. A genetic test might be warranted if there is a family history of inheritance. Liver function tests are a group of blood tests that doctors might use to evaluate the liver's ability to gather and store glycogen (sugar) and protein, produce bile, filter the blood, and produce cholesterol.

Drugs can accumulate in liver cells, leading to changes in levels of enzymes. Enzymes that are elevated may indicate an inflammatory or viral process as well as the use of certain medications such as steroids which need some time to clear from the body after discontinuation. The test isn't specific for any disease but can show if there is a liver problem even before symptoms occur, including cirrhosis and early hepatitis B and C infections. When first conducted, rapid elevations or decreases might be indications of acute injury or pre-clinically chronic injury respectively.

The liver may be the body's most important gland. It synthesizes nutrients from fat, carbohydrates, and protein into a form that can be absorbed by the blood to supply the cells, brain, and other tissues with a continuous supply of fuel. The liver also acts as a storage center for high-density energy reserves in times of food shortage or famine.

In response to viruses or bacteria which enter from our gut through their ingestion of contaminated water or insects’ excretions for example), substances called antibodies are manufactured in great numbers by specialized cells in an inflammatory reaction known as acute hepatitis. LFT helps measure the liver's endurance, by testing erythrocyte count, serum albumin level, bilirubin level and prothrombin time.

It's normal for your erythrocyte count to drop over time as you age. This is due mainly to the production of fewer red blood cells in your bone marrow. It may provide an indication of what is happening inside the liver with regard to the regeneration of new cells. An elevated or persistently high level can indicate cirrhosis or cancer. If it's persistently high, then requires radiologic imaging for diagnosis.

The liver function tests are blood tests that tell the physician how well the liver is working. The enzymes GGT, ALT, AST, and ALP are primarily tested to examine what should be healthy activities through three phases of hepatic metabolism. Since these enzymes exist primarily in the liver, they do not normally show up in any other tissue or fluid other than the bloodstream. If there is a disease that affects the cells within the liver, then inflammatory processes will ensue. This will lead to excessive production of oxygen-free radicals to facilitate cell death and release toxins into circulation which can affect all body systems including altering enzyme quantities, so they bump up against their normal reference ranges for evaluation.

The purpose of liver function tests is to diagnose and monitor a person's condition, based on levels of certain enzymes in the blood.

A high level of transaminases might be due to a variety of diseases or conditions, including hepatitis, cirrhosis, biliary obstruction from gallstones, or pancreatitis. Liver disease disrupting the production and release of albumin will also produce abnormally low-level albumin which can be detected with this test. A qualitative determination can be made if large amounts of Clotting Factor VIII are released into the bloodstream - Hepaetous Patina (HP) - leading to severe bleeding episodes independent from coagulation defects where plasma clotting normally should take place.

Liver function tests measure the level of different substances produced or used by the liver, such as albumin. The liver conditions may include fatty liver (hepatic steatosis), alcoholic hepatitis, cirrhosis, and many disorders affecting other parts of the body which ultimately damage the working capacity of your liver. Liver function tests are not meant to detect acute hepatitis or mild cases of elevated enzyme levels that commonly resolve on their own. Normal results suggest that there is no abnormality with your kidneys. Abnormal livers often show high amounts of creatinine kinase (CK) and alanine aminotransferase (ALT).

The liver is the body's only organ able to break down toxic compounds, so its function must be checked. The example you gave -- SGPT, or aspartate aminotransferase -- measures the level of a major liver enzyme. High levels could indicate damage from drugs also used for weight loss, such as acetaminophen/paracetamol (Tylenol) or metformin (Glucophage). Too-low levels of hepatocyte enzymes mean that the liver's not functioning properly and may develop complications like hepatitis and cirrhosis.

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Shortness of Breath Causes: From Common Triggers to Serious Health Conditions

Shortness of breath, medically known as dyspnea, is a symptom that ranges from mild discomfort during exertion to a distressing sensation of not getting enough air. In India, increasing air pollution, lifestyle diseases and respiratory infections have made breathlessness a frequent complaint across age groups. Understanding shortness of breath causes is essential to identify when it is harmless and when it signals a medical emergency.

 

What Is Shortness of Breath?

Shortness of breath refers to difficulty breathing or a feeling of air hunger.

It may present as:

  • rapid breathing

  • shallow breathing

  • tightness in the chest

  • inability to take a deep breath

The sensation can develop suddenly or gradually.

 

Common and Benign Causes of Shortness of Breath

Physical Exertion

During exercise, the body demands more oxygen.

Temporary breathlessness during:

  • climbing stairs

  • running

  • heavy physical work

is normal and resolves with rest.

 

Anxiety and Panic Attacks

Stress and anxiety alter breathing patterns.

Symptoms include:

  • rapid breathing

  • chest tightness

  • dizziness

These episodes often resolve with calming techniques.

 

Respiratory Causes of Shortness of Breath

Asthma

Asthma causes airway narrowing and inflammation.

Symptoms include:

  • wheezing

  • chest tightness

  • breathlessness during exertion or at night

Asthma is a leading cause of chronic breathlessness.

Chronic Obstructive Pulmonary Disease

COPD includes chronic bronchitis and emphysema.

Risk factors include:

  • smoking

  • indoor air pollution

  • occupational exposure

WHO identifies COPD as a major cause of breathlessness in adults.

 

Respiratory Infections

Infections such as pneumonia and bronchitis reduce lung capacity.

Breathlessness may be accompanied by:

  • cough

  • fever

  • chest pain

Severe infections require urgent treatment.

 

Heart-Related Causes of Shortness of Breath

Heart Failure

The heart fails to pump blood efficiently.

This leads to:

  • fluid accumulation in lungs

  • breathlessness on exertion

  • breathlessness while lying flat

ICMR data shows heart disease as a major contributor to unexplained breathlessness.

 

Coronary Artery Disease

Reduced blood supply to the heart can cause:

  • breathlessness

  • chest discomfort

  • fatigue

This may occur even without chest pain in some individuals.

 

Blood and Metabolic Causes

Anemia

Low hemoglobin reduces oxygen delivery.

Common symptoms include:

  • fatigue

  • breathlessness on mild activity

  • pale skin

NFHS-5 highlights anemia as highly prevalent in India.

 

Thyroid Disorders

Hyperthyroidism increases metabolic demand, causing breathlessness.

Hypothyroidism may contribute indirectly through weight gain and reduced stamina.

 

Lung Circulation Disorders

Pulmonary Embolism

A blood clot in the lungs causes sudden, severe breathlessness.

This is a medical emergency and may be accompanied by:

  • chest pain

  • coughing blood

  • fainting

Immediate treatment is critical.

 

Lifestyle-Related Causes

Obesity

Excess body weight restricts lung expansion.

Breathlessness occurs due to:

  • increased oxygen demand

  • reduced lung volumes

Weight management improves breathing efficiency.

 

Sedentary Lifestyle

Poor physical conditioning reduces respiratory muscle strength.

Even mild exertion may cause breathlessness.

 

Environmental and Occupational Factors

Air Pollution

Pollutants irritate airways and reduce lung function.

Urban populations experience higher rates of breathlessness.

Workplace Exposure

Dust, chemicals and fumes increase respiratory risk.

Protective measures are essential in high-risk occupations.

When Shortness of Breath Is a Warning Sign

Seek urgent care if breathlessness:

  • starts suddenly

  • worsens rapidly

  • occurs at rest

  • is associated with chest pain, bluish lips or confusion

These may indicate life-threatening conditions.

 

How Shortness of Breath Is Diagnosed

Evaluation may include:

  • physical examination

  • chest imaging

  • blood tests

  • lung function tests

  • heart evaluation

Diagnosis focuses on identifying the root cause.

 

Preventive Measures and Lifestyle Care

Prevention includes:

  • regular physical activity

  • pollution protection

  • smoking cessation

  • weight control

  • managing chronic conditions

Preventive healthcare reduces long-term risk.

 

Importance of Early Medical Evaluation

Delayed diagnosis can worsen outcomes, especially in:

  • heart disease

  • lung infections

  • anemia

Early care improves treatment success.

 

Conclusion

Shortness of breath causes range from temporary exertion and anxiety to serious heart, lung and blood disorders. While occasional breathlessness may be harmless, persistent or sudden symptoms should never be ignored. Understanding the underlying causes and seeking timely medical evaluation can prevent complications and save lives. Paying attention to changes in breathing is an essential step toward protecting overall health and wellbeing.

 

References

  • Indian Council of Medical Research (ICMR) – Respiratory and Cardiac Health Reports

  • World Health Organization (WHO) – Breathlessness and Chronic Disease Guidelines

  • National Family Health Survey (NFHS-5) – Anemia and Respiratory Health Data

  • Lancet – Dyspnea Evaluation and Outcomes Research

  • NITI Aayog – Non-Communicable Disease Prevention Reports

  • Statista – Respiratory Disease and Air Pollution Trends

See all

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