“Hepatic stenosis” is not a standard medical term, but it’s a common mix-up of two real conditions. Most people searching this phrase are looking for information about hepatic steatosis, which is the medical name for fatty liver disease. Less commonly, “hepatic stenosis” could refer to hepatic artery stenosis, a narrowing of the blood vessel that supplies the liver. This article covers both, starting with the far more common one.
Hepatic Steatosis: The Fatty Liver Condition
Hepatic steatosis means fat has built up inside your liver cells. A healthy liver contains very little fat. When at least 5% of liver cells contain fat droplets, that crosses the threshold into clinical steatosis. The condition is extremely common: roughly 38% of all adults worldwide have it, along with 7 to 14% of children and adolescents.
The newer umbrella term for this condition is metabolic dysfunction-associated steatotic liver disease, or MASLD. You may also see it called NAFLD (non-alcoholic fatty liver disease), which was the standard name until recently. Both refer to fat accumulation in the liver that isn’t caused by heavy alcohol use.
How Fat Builds Up in the Liver
Your liver constantly processes fats from your bloodstream, but problems start when more fat arrives than the liver can handle. In fasting conditions, about 81% of the fat that ends up stored in liver cells comes from fatty acids already circulating in your blood. After eating, dietary fat contributes a larger share, around 26%, while the circulating pool drops to about 61%. The liver also manufactures some fat on its own through a process called de novo lipogenesis, which accounts for 7 to 9% of liver fat depending on whether you’ve recently eaten.
Insulin resistance throws this system off balance. When your cells stop responding properly to insulin, your body releases more fatty acids from fat tissue into the bloodstream, flooding the liver. At the same time, insulin resistance ramps up the liver’s own fat production. High blood sugar and elevated fatty acids in the blood further impair the liver’s ability to burn fat for energy. The result is a traffic jam: fat accumulates in liver cells faster than it can be processed or exported.
Key Risk Factors
The biggest risk factors for hepatic steatosis overlap heavily with metabolic syndrome:
- Abdominal fat. Belly fat, specifically the visceral fat surrounding your organs, is more strongly linked to fatty liver than overall body weight. This is one reason the condition affects people across a range of BMIs. Asian populations, for instance, tend to carry more visceral fat at lower body weights, which shifts the risk threshold.
- Insulin resistance and type 2 diabetes. Insulin resistance is considered the central driver of fatty liver development. The two conditions reinforce each other: fatty liver worsens insulin resistance, and insulin resistance accelerates fat storage in the liver.
- High triglycerides. People with fatty liver frequently have elevated blood triglycerides and higher levels of small, dense LDL cholesterol, the type most associated with cardiovascular risk.
Grades of Fatty Liver
Doctors often grade steatosis based on how much of the liver is affected. A common tool for measuring this without a biopsy is a FibroScan, which uses sound waves to estimate both fat content and liver stiffness. The fat measurement is called a CAP score, reported in decibels per meter (dB/m).
- S1 (mild): CAP score of 238 to 260 dB/m, meaning roughly 11 to 33% of the liver is affected.
- S2 (moderate): CAP score of 260 to 290 dB/m, with 34 to 66% of the liver affected.
- S3 (severe): CAP score above 290 dB/m, where more than two-thirds of the liver contains excess fat.
A higher grade doesn’t automatically mean more liver damage. What matters more is whether inflammation and scarring (fibrosis) have developed. Simple steatosis, fat without significant inflammation, often causes no symptoms and may remain stable for years. The concern is progression to steatohepatitis, where inflammation begins damaging liver cells and can eventually lead to fibrosis or cirrhosis.
Symptoms and How It’s Found
Most people with hepatic steatosis feel perfectly fine. The liver doesn’t have pain receptors inside it, so fat accumulation alone rarely causes discomfort. Some people notice a dull ache in the upper right abdomen if the liver becomes enlarged enough to stretch its outer capsule, but this is uncommon in early stages.
Fatty liver is usually discovered incidentally, during blood work that shows mildly elevated liver enzymes or on an imaging scan done for another reason. An ultrasound can detect fat in the liver once it reaches moderate levels, and a FibroScan provides more precise measurements of both fat and stiffness. Liver biopsy remains the most definitive test but is reserved for cases where the degree of inflammation or scarring needs to be confirmed.
Reversing Fatty Liver Through Weight Loss
The most effective treatment for hepatic steatosis is weight loss, and the results can be dramatic. Losing 5 to 7% of your total body weight typically reduces liver fat. Losing 10% or more can actually reverse fibrosis, even in advanced stages. In one study of patients with confirmed liver scarring, 63% of those who lost at least 10% of their body weight saw their fibrosis improve, compared to just 9% of those who lost less. On multivariate analysis, that level of weight loss was the only factor that predicted fibrosis regression.
The method of weight loss matters less than the result. Whether through dietary changes, increased physical activity, or bariatric surgery, the liver responds to the reduced metabolic burden. Regular exercise helps even without dramatic weight loss, partly because it improves insulin sensitivity and reduces visceral fat independently.
Medication for Advanced Cases
For people who have progressed beyond simple fat accumulation to steatohepatitis with moderate to advanced scarring, the FDA approved the first targeted medication in 2024. Called Rezdiffra (resmetirom), it works by activating a thyroid hormone receptor in the liver that helps the organ process fat more efficiently. It’s specifically indicated for adults with noncirrhotic steatohepatitis and stage F2 to F3 fibrosis, meaning significant scarring that hasn’t yet reached cirrhosis. The drug is used alongside diet and exercise, not as a replacement for them.
Hepatic Artery Stenosis: The Vascular Condition
If you’re searching for hepatic stenosis in the context of a liver transplant or vascular problem, you may be thinking of hepatic artery stenosis. This is a narrowing of the hepatic artery, the main blood vessel that delivers oxygen-rich blood to the liver. It’s most commonly seen as a complication after liver transplantation, where the surgically reconnected artery can narrow due to scarring or clot formation.
Hepatic artery stenosis is diagnosed primarily through Doppler ultrasound, which measures blood flow patterns in the artery. Doctors look at several indicators, including how quickly blood accelerates during each heartbeat and the resistance pattern of the flow. In transplant recipients, combined ultrasound measurements can detect significant arterial narrowing with about 97% sensitivity, though the specificity is lower at 64%, meaning some false positives occur.
This condition is far less common than fatty liver disease and is almost exclusively relevant to people who have undergone liver transplantation or who have specific vascular disorders. If your doctor mentioned hepatic stenosis after a transplant, they’re monitoring for this complication to ensure your new liver is getting adequate blood supply.