Fatty liver assessment (MASLD)

Blood test to assess fatty liver, also known as hepatic steatosis or metabolic dysfunction-associated steatotic liver disease (MASLD). It includes transaminases, the FIB-4 index, glucose, glycated haemoglobin, cholesterol, iron metabolism, TSH and hepatitis B and C serology. It assesses the metabolic component, estimates the risk of fibrosis and looks for other causes that can coexist with fat build-up in the liver.

No prescription or appointment needed

Results in 1-2 working days

Includes: AST, ALT and GGT · Full blood count · FIB-4 index · Glucose · Glycated haemoglobin · Lipid profile and ratios · Hepatitis B surface antigen. 11 in total. See what each one measures

What it is for

It is used to structure the assessment after an ultrasound has shown hepatic steatosis or when transaminases are persistently raised. It answers three questions: whether there are associated metabolic abnormalities, whether FIB-4 suggests that advanced fibrosis should be excluded, and whether there are findings pointing towards viral hepatitis, iron overload or a thyroid abnormality.

Bear in mind that a blood test does not directly measure the amount of fat or confirm the degree of fibrosis. When FIB-4 or the other results justify it, the assessment can be completed with an ultrasound, elastography or other tests.

When it is recommended

Fatty liver or hepatic steatosis seen on an ultrasound
Repeatedly raised transaminases or GGT
Type 2 diabetes, obesity or metabolic syndrome with a risk of liver disease
Liver abnormalities whose cause has not been investigated
Follow-up of fatty liver, when you want to compare FIB-4 and metabolic factors with previous checks

Clinical comment

Fatty liver is not assessed with transaminases alone. They can be normal even when there is steatosis or fibrosis, and they can also rise for reasons unrelated to metabolism. That is why we have included the metabolic block, hepatitis B and C, iron metabolism and TSH.

FIB-4 is an initial tool for estimating the probability of advanced fibrosis. A low result can be reassuring in certain age groups, while an intermediate or high value means the context has to be assessed and, often, the investigation completed. On its own it does not distinguish between simple fatty liver and fibrosis, and it is less accurate in young or older people.

We also measure transferrin saturation. Ferritin can rise with inflammation or with the liver disease itself, so an isolated high ferritin does not prove iron overload.

Dr. Antonio Mas

What is tested

AST, ALT and GGT: Enzymes that help identify liver damage, although they can be normal even when there is fatty liver.
Full blood count: Checks the blood cells and provides the platelet count needed to calculate FIB-4.
FIB-4 index (calculated): Estimates the probability of advanced liver fibrosis from age, transaminases and platelets.
Glucose: Measures blood sugar at the time the sample is taken.
Glycated haemoglobin (HbA1c): Reflects average glucose over the last two or three months and can reveal abnormalities associated with metabolic fatty liver.
Lipid profile (total cholesterol, HDL, LDL, triglycerides) and ratios
Hepatitis B surface antigen (HBsAg): Used to look for active infection with the hepatitis B virus.
Hepatitis C virus antibodies (anti-HCV): Used as an initial test for possible hepatitis C infection. A positive result requires confirmation.
Ferritin: Assesses iron stores, although it can also rise with inflammation or with the liver disease itself.
Transferrin saturation: Helps identify iron overload and is more specific than ferritin alone.
TSH: Checks whether there is a thyroid abnormality that could contribute to the metabolic profile or to raised transaminases.

These tests are used to calculate Índice FIB-4. They are not separate tests.

How to prepare

Fast for 8 to 12 hours. You can drink water. Avoid alcohol for the three days before and intense exercise the day before, because they can change transaminases and GGT.

You can add

Without another needle. It is offered when you order, so you do not have to decide now.

Sugar, insulin and inflammationAssesses insulin resistance through fasting insulin and the HOMA-IR index, plus average blood sugar over the last three months and low-grade inflammation.+€59.00
Advanced lipid panelExtends standard cholesterol with ApoB, lipoprotein(a) and homocysteine, markers that refine the assessment of cardiovascular risk and are not usually measured routinely.+€59.00

Related blood tests

We have other profiles in Heart and diabetes with more or fewer tests:

The most comprehensive is not always the most useful. If you are not sure, the one we recommend to start with is Cardiovascular risk blood test with ApoB and Lp(a).

What it is based on

European Association for the Study of the Liver, EASD y EASO · Diabetologia 67(11):2375-2392
EASL-EASD-EASO Clinical Practice Guidelines on the management of metabolic dysfunction-associated steatotic liver disease (MASLD)
Recommends looking for fatty liver with fibrosis in people with type 2 diabetes, abdominal obesity with another metabolic factor, or abnormal transaminases, and doing so in two steps: first a non-proprietary blood index such as FIB-4, and only then elastography. That is the index this assessment calculates.

Protocol designed by Dr. Antonio Mas, specialist in Endocrinology and Nutrition, Spanish medical licence no. 080846289, and reviewed in September 2026.

This blood test is a standardised protocol and does not replace a medical consultation. If you have symptoms, a known condition or a complex clinical situation, speak to your doctor.