Liver tests: guide to liver function tests, normal values and interpretation

Liver tests: why check your liver

Liver tests are among the most important tests for monitoring the body’s overall health. The liver performs over 500 vital functions, including:

• metabolizing nutrients

• filtering toxins

• producing essential proteins

• regulating blood clotting

Many liver diseases, such as steatosis (fatty liver) or hepatitis, can remain asymptomatic for years. For this reason, blood tests are a fundamental tool for early diagnosis.

If your values are abnormal, it is always advisable to see a specialist. Learn more about fatty liver and its risk factors on Nefrocenter.

When to have liver tests

Routine screening (over 40) with liver tests

After age 40 it is advisable to have a liver panel done periodically, especially if your lifestyle puts you at risk.

Risk factors

It is important to have your liver checked if you have:

• overweight or obesity

• diabetes

• high cholesterol

• alcohol consumption

• long-term use of medications

• viral infections (hepatitis)

Suspicious symptoms

Although often absent, some signs may point to a liver problem:

• persistent fatigue

• pain in the right side

• jaundice (yellow skin)

• dark urine

• nausea

Follow-up of existing conditions

People with liver disease must regularly monitor:

• transaminases

• bilirubin

• blood clotting

Liver tests (liver panel)

The so-called liver panel includes several parameters that make it possible to assess how well the liver is working.

Transaminases (AST and ALT)

Transaminases are the best-known indicators of liver health.

• ALT (alanine aminotransferase) → more specific to the liver

• AST (aspartate aminotransferase) → also found in muscles

What they measure

They signal damage to liver cells.

Reference values

• ALT: 7-56 U/L

• AST: 10-40 U/L

High transaminases: what to do?

High transaminases do not always indicate a serious disease, but they must be evaluated.

Most common causes:

• fatty liver

• alcohol

• medications

• viral infections

• intense physical activity

If the values stay elevated for more than 3-6 months, further investigation is needed.

Gamma-GT (GGT)

Gamma GT is a very sensitive enzyme.

Function and meaning

It points to problems in the bile ducts or the liver.

High gamma GT: causes

• alcohol consumption

• medications

• cholestasis

• hepatitis

It is one of the first values to rise in liver damage.

Alkaline phosphatase (ALP)

Role

Involved in bone metabolism and in the bile ducts.

Elevated values

May indicate:

• bile duct obstruction

• liver diseases

• bone diseases

Bilirubin (total, direct, indirect)

Bilirubin comes from the breakdown of red blood cells.

Metabolism

The liver processes it and eliminates it through bile.

High bilirubin

Can cause:

• jaundice

• dark urine

• pale stools

Albumin

Albumin is a protein produced by the liver.

Meaning

It assesses the liver’s ability to synthesize substances.

Low values

May indicate:

• liver failure

• malnutrition

• chronic diseases

PT/INR (prothrombin time)

PT/INR measures the ability of the blood to clot.

An abnormal value may indicate impaired liver function.

Blood ammonia

Assesses ammonia levels in the blood.

When it is elevated

May indicate:

• advanced liver failure

• hepatic encephalopathy

Table of normal values for liver tests (updated 2026)

Differences between men and women in liver test results

• Men tend to have slightly higher values

• Women may have hormonal variations

Important note

Values may vary depending on:

• age

• laboratory

• ethnicity

Imaging liver tests

When blood tests are abnormal, second-level tests are used.

Abdominal ultrasound

First test to assess:

• fatty liver

• nodules

• size

CT scan with contrast

Allows a detailed evaluation of the structures.

Magnetic resonance imaging (MRI)

Indicated for complex liver lesions.

FibroScan (elastography)

Measures liver stiffness and the degree of fibrosis.

Liver biopsy

An invasive test, used in the most complex cases.

To learn more about advanced liver diagnostics you can also consult the hepatology center at Rome American Hospital.

How to prepare for liver tests

Fasting

Fasting for at least 8-12 hours is recommended.

Medications

Some medications can alter the results: consult your doctor.

Physical activity

Avoid intense exertion in the 24 hours beforehand.

Alcohol

Do not drink alcohol for at least 48 hours beforehand.

Interpreting the results: when to worry about your liver test results

One of the most frequent questions is: when should you worry about high transaminases?

It is important to evaluate:

• how high they are

• for how long

• any associated symptoms

Warning signs

• very high values (more than 3 times the limit)

• persistence for more than 6 months

• presence of jaundice

• abnormal INR or albumin

In these cases it is essential to see a specialist.

Costs and copay exemptions for liver tests

Liver tests are often part of routine tests.

• National Health Service (SSN): variable copay

• exemption: for chronic conditions

• private: €20-100 depending on the panel

Prevention: how to keep your liver healthy

To protect your liver it is essential to:

• follow a balanced diet

• limit alcohol

• maintain a healthy weight

• get physical activity

• monitor blood glucose and cholesterol

Prevention remains the most effective strategy.

Liver tests are essential

Having liver tests done is a fundamental tool for monitoring your health and preventing even serious diseases.

Many liver conditions can be reversible if detected early.

Regularly checking your liver values means taking care of your long-term well-being.

⚠️ Important disclaimer

The values given are indicative. Test results must always be interpreted by a specialist doctor who takes into account age, sex, ethnic origin, medical history and other individual factors.