Conditions · Gastroenterology and hepatology

Metabolic dysfunction-associated steatotic liver disease (MASLD/NAFLD) !

Fat builds up in the liver in people with obesity, diabetes or other metabolic risks. Usually silent, it can progress to scarring, cirrhosis and liver cancer.

Updated 2026-11-01

Structures involved

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In the clinical exam

Why it happens

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What it is

Hepatic steatosis in a person with at least one cardiometabolic risk factor and no other cause of fat in the liver. It was formerly called non-alcoholic fatty liver disease (NAFLD); its inflammatory form is MASH (formerly NASH).

Who gets it

The most common chronic liver disease worldwide, affecting roughly a third of adults, and Latin America reports some of the highest prevalences. It is rising in Colombia with obesity and type 2 diabetes, and it is becoming a leading cause of cirrhosis, liver cancer and transplantation.

Causes

Insulin resistance with overweight or abdominal obesity
Type 2 diabetes or prediabetes
Hypertension, high triglycerides or low HDL cholesterol
Genetic variants (for example PNPLA3) that raise susceptibility
MetALD: MASLD plus moderate alcohol intake, a separate overlap category

Risk factors

Obesity, especially central obesity
Type 2 diabetes
Metabolic syndrome and dyslipidaemia
Sedentary lifestyle and diets high in fructose and ultra-processed foods
Polycystic ovary syndrome, obstructive sleep apnoea and hypothyroidism

Pathophysiology

Insulin resistance increases the release of free fatty acids from adipose tissue and de novo lipogenesis in the liver, so triglycerides accumulate in hepatocytes. Lipotoxicity, oxidative stress and gut-derived signals cause hepatocyte injury and inflammation (MASH), which activates stellate cells and lays down fibrosis that can progress to cirrhosis.

Classification

MASL: steatosis without significant inflammation
MASH: steatohepatitis with hepatocyte ballooning and inflammation
Fibrosis stage F0 to F4 (F4 is cirrhosis); fibrosis stage best predicts outcome
MetALD: overlap with moderate alcohol intake

Symptoms and signs

Usually no symptoms; often found by raised liver enzymes or on ultrasound
Fatigue
Vague discomfort in the right upper quadrant
Mild hepatomegaly
Signs of cirrhosis in advanced disease (jaundice, ascites, spider angiomas)

Diagnosis

Clinical: Steatosis plus at least one cardiometabolic criterion (BMI or waist, glucose or diabetes, blood pressure, triglycerides, HDL), with alcohol intake and other liver diseases assessed.
Tests: Liver enzymes (ALT often higher than AST, but may be normal), lipid profile, HbA1c, platelets; viral hepatitis serology and other tests to exclude other causes. Non-invasive fibrosis scores such as FIB-4 stratify risk; biopsy is reserved for uncertain cases.
Imaging: Ultrasound shows a bright (hyperechoic) liver. Transient elastography or MR elastography measures stiffness to stage fibrosis; MRI proton density fat fraction quantifies fat.

Differential diagnosis

Alcohol-related liver disease
Chronic viral hepatitis B or C
Drug-induced steatosis (corticosteroids, amiodarone, methotrexate, tamoxifen)
Wilson disease and haemochromatosis
Autoimmune hepatitis

Goal of treatment

Reduce liver fat, inflammation and fibrosis through weight loss and metabolic control, and lower cardiovascular risk, which is the main cause of death.

Treatment

Lifestyle: Gradual sustained weight loss through a healthier diet (for example a Mediterranean pattern) and regular exercise; around 7 to 10 percent of body weight improves inflammation and fibrosis. Limiting or avoiding alcohol.
Medical: Treatment of diabetes, dyslipidaemia and hypertension; GLP-1 receptor agonists, pioglitazone and statins are used in selected patients. Thyroid hormone receptor-beta agonists and GLP-1 receptor agonists are approved in some countries for MASH with significant fibrosis.
Surgical: Metabolic (bariatric) surgery in selected people with severe obesity.
Follow-up: Periodic fibrosis assessment; people with cirrhosis need ultrasound surveillance for liver cancer and screening for varices.

Complications

Progression to MASH, advanced fibrosis and cirrhosis
Hepatocellular carcinoma, which can arise even without cirrhosis
Cardiovascular disease, the main cause of death
Higher risk of type 2 diabetes and chronic kidney disease

Prognosis

Most people with simple steatosis do not progress to cirrhosis, but MASH with fibrosis can. Fibrosis stage is the strongest predictor of liver-related outcomes, and cardiovascular disease causes most deaths.

Prevention

Maintaining a healthy weight and regular physical activity
Limiting sugar-sweetened drinks and ultra-processed food
Screening for fibrosis in people with type 2 diabetes or obesity with other risk factors

Test yourself

Think of the answer, then tap the question to see it.

What replaced the term NAFLD in 2023?

Metabolic dysfunction-associated steatotic liver disease (MASLD); NASH became MASH.

Which histological feature best predicts outcomes in MASLD?

The stage of fibrosis.

What is the typical aminotransferase pattern in MASLD?

Mild elevation with ALT usually higher than AST; an AST/ALT ratio above 2 suggests alcohol-related disease.

Which non-invasive score is used first to stratify fibrosis risk?

FIB-4 (age, AST, ALT and platelets), followed by elastography if it is not low.

What is the leading cause of death in people with MASLD?

Cardiovascular disease.

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Educational information, not medical advice. For any symptom, see a health professional.

Sources: Steatotic Liver Disease | Fatty Liver Disease | MedlinePlus (MedlinePlus (U.S. National Library of Medicine), 2026).

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Representative model, for educational purposes only.

Liver highlighted on the Durgical 3D model