• 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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Sleep Debt and Its Impact on the Body: Hidden Risks of Chronic Sleep Loss

Sleep is not a luxury; it is a biological necessity. Yet in today’s fast-paced world, many people consistently sacrifice sleep due to work demands, screen time and stress. Over time, insufficient sleep accumulates into what is known as sleep debt. Understanding sleep debt and its impact on the body is essential because chronic sleep loss silently affects nearly every organ system.

According to the World Health Organization and global sleep research, chronic sleep deprivation is associated with increased risk of cardiovascular disease, metabolic disorders and mental health conditions.

 

What Is Sleep Debt?

Sleep debt refers to the cumulative effect of not getting enough sleep.

For example:

  • if you need 8 hours but sleep 6 hours daily

  • you accumulate 2 hours of sleep debt per night

Over a week, that equals 14 hours of lost sleep.

This deficit places strain on the body.

 

Why Sleep Is Critical for Health

Sleep supports:

  • brain function

  • immune response

  • hormonal regulation

  • tissue repair

  • memory consolidation

Without adequate sleep, these processes become impaired.

 

Immediate Effects of Sleep Debt

Short-term consequences include:

  • daytime fatigue

  • poor concentration

  • mood swings

  • irritability

  • reduced reaction time

Even one night of poor sleep affects cognitive performance.

 

Sleep Debt and Hormonal Imbalance

Sleep regulates several key hormones.

Chronic sleep loss disrupts:

  • cortisol

  • insulin

  • leptin and ghrelin (hunger hormones)

This imbalance affects appetite, stress and metabolism.

 

Impact on Metabolic Health

Sleep debt increases:

  • insulin resistance

  • blood sugar fluctuations

  • abdominal fat accumulation

ICMR and NFHS-5 data show rising metabolic disorders in India, partly linked to lifestyle patterns including poor sleep.

 

Increased Risk of Obesity

When sleep is insufficient:

  • appetite hormones increase

  • cravings for high-calorie foods rise

  • impulse control weakens

Sleep deprivation promotes weight gain.

 

Sleep Debt and Immunity

The immune system relies heavily on sleep.

Chronic sleep loss:

  • reduces infection-fighting cells

  • increases inflammation

  • slows recovery from illness

Lancet research confirms that sleep deprivation weakens immune response.

 

Cardiovascular Consequences

Sleep debt increases risk of:

  • hypertension

  • heart disease

  • stroke

Poor sleep affects blood pressure regulation and vascular health.

 

Mental Health Impact

Sleep and mental health are deeply connected.

Sleep debt contributes to:

  • anxiety

  • depression

  • emotional instability

Chronic insomnia is both a cause and consequence of mental health disorders.

 

Cognitive Decline and Brain Health

Lack of sleep impairs:

  • memory

  • attention

  • decision-making

Over time, chronic sleep deprivation may increase risk of neurodegenerative disorders.

 

Sleep Debt and Inflammation

Chronic sleep loss elevates inflammatory markers.

Persistent inflammation contributes to:

  • metabolic syndrome

  • cardiovascular disease

  • autoimmune conditions

Preventing sleep debt reduces systemic inflammation.

 

Can Sleep Debt Be Recovered?

Short-term sleep debt can be partially recovered through:

  • consistent longer sleep

  • improved sleep hygiene

However, chronic sleep deprivation requires long-term behavioural changes.

Weekend “catch-up sleep” offers temporary relief but does not fully reverse long-standing sleep debt.

 

Warning Signs of Sleep Debt

Common indicators include:

  • reliance on caffeine

  • difficulty waking up

  • daytime drowsiness

  • poor focus

  • frequent illness

Persistent symptoms require lifestyle correction.

 

Practical Strategies to Reduce Sleep Debt

Maintain a Consistent Sleep Schedule

Go to bed and wake up at the same time daily.

 

Limit Screen Exposure Before Bed

Blue light suppresses melatonin production.

 

Create a Sleep-Friendly Environment

Dark, quiet and cool environments improve sleep quality.

 

Manage Stress

Relaxation techniques reduce cortisol levels and support sleep.

 

Avoid Heavy Meals and Caffeine at Night

These disrupt sleep cycles.

 

Role of Preventive Health Checkups

Screening helps detect:

  • hypertension

  • metabolic imbalance

  • stress-related conditions

Sleep quality assessment should be part of preventive care.

 

Long-Term Benefits of Adequate Sleep

Restorative sleep supports:

  • stable mood

  • strong immunity

  • healthy weight

  • improved productivity

  • reduced disease risk

Sleep is foundational to wellness.

 

Conclusion

Understanding sleep debt and its impact on the body highlights the critical role sleep plays in maintaining physical and mental health. Chronic sleep loss disrupts hormones, weakens immunity, increases metabolic risk and affects heart health. While occasional sleep loss may be manageable, consistent deprivation carries serious long-term consequences. Prioritising adequate, high-quality sleep is one of the most powerful steps toward protecting overall health and preventing chronic disease.

 

References

  • World Health Organization (WHO) – Sleep and Non-Communicable Diseases

  • Indian Council of Medical Research (ICMR) – Lifestyle Disorders and Sleep Patterns

  • National Family Health Survey (NFHS-5) – Adult Health Indicators

  • Lancet – Sleep Deprivation and Chronic Disease Research

  • NITI Aayog – Preventive Healthcare and Lifestyle Risk Factors

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