• 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.

Read Blog
How Cold Weather Affects Health: Understanding Winter’s Impact on the Body

How Cold Weather Affects Health: Understanding Winter’s Impact on the Body

Seasonal changes influence human health more than most people realise. Cold weather, in particular, places unique stress on the body and can worsen existing health conditions while increasing susceptibility to new illnesses. Understanding how cold weather affects health is essential for preventing seasonal complications and maintaining wellbeing during winter months.

In India, winter-related health issues vary by region but commonly include respiratory infections, cardiovascular strain and joint discomfort. According to the Indian Council of Medical Research (ICMR) and World Health Organization (WHO), cold exposure is associated with increased morbidity, especially among older adults and people with chronic conditions.

 

Why Cold Weather Impacts the Body

The human body works constantly to maintain core temperature. In cold environments:

  • blood vessels constrict to conserve heat
     

  • energy expenditure increases
     

  • immune responses may weaken
     

  • organs work harder to maintain balance
     

These adaptations, while protective, also create health vulnerabilities.

 

Increased Risk of Infections

Weakened Immune Response

Cold weather can suppress immune function, making it harder for the body to fight infections.

Factors contributing to winter infections include:

  • reduced vitamin D due to less sunlight
     

  • dry air affecting mucosal defenses
     

  • closer indoor contact
     

Common winter infections include colds, flu and respiratory illnesses.

 

Respiratory Health Problems

Cold air irritates the respiratory tract.

This can lead to:

  • worsening asthma symptoms
     

  • bronchitis flare-ups
     

  • increased cough and breathlessness
     

WHO reports higher hospital admissions for respiratory illnesses during colder months.

 

Impact on Heart Health

Cold temperatures affect cardiovascular function.

Blood Vessel Constriction

Cold causes blood vessels to narrow, increasing:

  • blood pressure
     

  • heart workload
     

This raises the risk of:

  • heart attacks
     

  • strokes
     

People with existing heart disease are particularly vulnerable.

 

Joint and Muscle Pain

Cold weather affects musculoskeletal health.

Common complaints include:

  • joint stiffness
     

  • muscle aches
     

  • worsening arthritis pain
     

Lower temperatures reduce joint lubrication and increase sensitivity to pain.

 

Metabolic and Weight Changes

Winter often leads to:

  • reduced physical activity
     

  • increased calorie intake
     

  • metabolic slowdown
     

These changes contribute to weight gain and worsen metabolic conditions such as diabetes.

 

Skin and Hydration Issues

Cold air holds less moisture.

This leads to:

  • dry skin
     

  • cracked lips
     

  • worsening eczema
     

Dehydration is also common as thirst perception reduces in cold weather.

 

Mental Health Effects

Seasonal changes can influence mental wellbeing.

Cold weather is associated with:

  • low mood
     

  • reduced motivation
     

  • seasonal affective symptoms
     

Limited sunlight affects circadian rhythm and serotonin levels.

 

Cold Weather and Older Adults

Elderly individuals face higher risks due to:

  • reduced temperature regulation
     

  • weaker immunity
     

  • existing chronic conditions
     

Winter-related complications are a significant cause of hospitalisation in older populations.

 

Why Chronic Diseases Worsen in Winter

Conditions such as:

  • hypertension
     

  • arthritis
     

  • asthma
     

  • diabetes
     

often worsen due to reduced activity, stress on organs and infection risk.

 

Preventive Strategies for Winter Health

Maintain Body Warmth

Layered clothing and warm environments reduce cold stress.

 

Support Immunity

Adequate nutrition, vitamin intake and sleep strengthen immune defences.

 

Stay Physically Active

Indoor exercises and regular movement prevent stiffness and metabolic decline.

 

Manage Chronic Conditions

Regular monitoring and medication adherence are critical during winter.

 

Hydration and Skin Care

Drinking fluids and using moisturisers prevent dehydration and skin damage.

 

Role of Preventive Healthcare

Preventive healthcare helps:

  • identify seasonal risk factors
     

  • adjust treatment plans
     

  • prevent winter complications
     

NITI Aayog highlights seasonal preparedness as an important public health strategy.

When to Seek Medical Help

Medical attention is necessary if:

  • infections persist or worsen
     

  • chest pain or breathlessness occurs
     

  • joint pain limits mobility
     

  • mental health symptoms interfere with daily life
     

Early care prevents serious outcomes.

 

Long-Term Impact of Ignoring Winter Health Risks

Ignoring cold weather effects may lead to:

  • severe infections
     

  • cardiovascular events
     

  • chronic pain progression
     

  • reduced quality of life
     

Seasonal awareness plays a critical role in long-term health.

 

Conclusion

Understanding how cold weather affects health allows individuals to take timely preventive measures. Winter increases the risk of infections, heart strain, respiratory problems, joint pain and mental health challenges. With proper warmth, nutrition, activity and preventive healthcare, most cold-related health issues are manageable and preventable. Seasonal care is not optional—it is essential for protecting health and wellbeing throughout the colder months.

 

References

  • ICMR – Seasonal Health and Infectious Disease Reports

  • National Family Health Survey (NFHS-5) – Seasonal Morbidity Data

  • NITI Aayog – Preventive Healthcare and Seasonal Preparedness Strategy

  • WHO – Cold Weather and Health Impact Guideline

  •  Lancet – Seasonal Variation in Cardiovascular and Respiratory Diseases

  • Statista – Winter Health Trends and Illness Data

  • Indian Journal of Public Health – Climate and Health Studies

See all

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