Understanding Non-Alcoholic Fatty Liver Disease: Diagnosis and Progression

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• What is NAFLD?
• NAFLD Prevalence and Patient Profile
• Progression to NASH and Cirrhosis
• Liver Cancer Risk in Advanced NAFLD
• NAFLD Diagnostic Criteria and Tests
• Non-Invasive Diagnostic Tests
• Full Transcript

What is NAFLD?

Non-alcoholic fatty liver disease (NAFLD) is a condition characterized by the accumulation of fat in liver cells. Dr. Scott Friedman, MD, a leading hepatologist, explains that this condition is strongly associated with the growing global prevalence of obesity. NAFLD encompasses a spectrum of liver damage, starting with simple steatosis, which is fat accumulation alone.

The disease can progress to a more severe inflammatory form known as non-alcoholic steatohepatitis (NASH). This progression is a critical focus of diagnosis and treatment.

NAFLD Prevalence and Patient Profile

Dr. Scott Friedman, MD, highlights the staggering prevalence of non-alcoholic fatty liver disease. It is estimated that approximately 40% of the American population has some degree of hepatic fat accumulation. While the vast majority of NAFLD patients are overweight or obese, Dr. Scott Friedman, MD, notes an important exception.

He states that about 5% of cases occur in lean individuals, indicating that body weight is not the sole risk factor. This makes widespread awareness and screening important for a broad patient population.

Progression to NASH and Cirrhosis

The progression from simple NAFLD to non-alcoholic steatohepatitis (NASH) marks a significant worsening of the disease. Dr. Scott Friedman, MD, describes NASH as a stage where inflammation and injury to liver cells (hepatocytes) are present alongside the fat. This ongoing injury triggers a wound-healing response in the liver, leading to the slow accumulation of scar tissue, a process known as fibrosis.

Dr. Scott Friedman, MD, explains that unchecked fibrosis can advance to cirrhosis, an advanced stage of liver disease characterized by widespread scarring and loss of liver function.

Liver Cancer Risk in Advanced NAFLD

A serious complication of advanced non-alcoholic fatty liver disease is the development of liver cancer. Dr. Scott Friedman, MD, specifically identifies hepatocellular carcinoma (HCC) as the primary type of liver cancer associated with NAFLD and NASH. This risk is particularly elevated in patients who have progressed to cirrhosis.

The emergence of cancer underscores the critical need for early diagnosis, monitoring, and effective treatment strategies to halt disease progression before it reaches these advanced stages.

NAFLD Diagnostic Criteria and Tests

Establishing a diagnosis of non-alcoholic fatty liver disease requires demonstrating the presence of fat in the liver. Dr. Scott Friedman, MD, outlines the diagnostic pathway, which relies on a combination of clinical assessment and testing. A key criterion is the exclusion of significant alcohol consumption, which can cause a similar pattern of liver injury.

Dr. Scott Friedman, MD, notes that the most definitive diagnostic method is a liver biopsy. This invasive procedure allows physicians to examine the liver tissue directly under a microscope to confirm fat, inflammation, and fibrosis.

Non-Invasive Diagnostic Tests

For most patients, diagnosis begins with non-invasive tests. Dr. Scott Friedman, MD, details several imaging modalities that can detect hepatic fat. These include abdominal ultrasound, which is often the first-line test, as well as CT and MRI scans.

Dr. Friedman also discusses the role of vibration-controlled transient elastography, commonly known as FibroScan. This specialized ultrasound technology measures liver stiffness, which serves as a proxy for fibrosis and scarring, providing crucial staging information without a biopsy.

Full Transcript

Dr. Anton Titov, MD: Professor Friedman, what is non-alcoholic fatty liver disease?

Dr. Anton Titov, MD: What are the diagnostic criteria for it?

So let me provide a little context. As many of us know, there is a growing prevalence of obesity, and that is associated with complications in many systems, including diabetes, hypertension, hyperlipidemia, and among those also is included the possibility of fat accumulating in the liver.

Most patients who have non-alcoholic fatty liver disease are overweight or obese, although it can occur in about 5% of patients in lean individuals.

Dr. Scott Friedman, MD: But NAFLD or non-alcoholic fatty liver disease refers to the presence of either fat alone or a more advanced stage known as non-alcoholic steatohepatitis or NASH, in which in addition to fat, there's the accumulation of inflammation, injury to liver cells and the slow but steady accumulation of scar or fibrosis that can lead in some cases to the advanced liver disease known as cirrhosis.

NAFLD can also be complicated, particularly at advanced stages, by the emergence of cancer, primarily hepatocellular carcinoma or primary liver cancer.

It's estimated that somewhere in the order of 40% of Americans have some degree of fat in their liver. Of course, most of them only have fat, but probably about 20 to 25% of that 40 million have NASH as well.

And so it's a very prevalent problem. It's often below the radar even for physicians, let alone patients. And it portends a rising risk of advanced liver disease if we don't begin to understand and treat it effectively.

Dr. Anton Titov, MD: Are there specific diagnostic criteria and the key diagnostic tests that are performed to identify clinical NAFLD?

Dr. Scott Friedman, MD: Yes, there are both non-invasive and more invasive tests that can establish the presence of NAFLD. Because NAFLD requires the presence of fat, there are a number of imaging tests, particularly ultrasound.

But also MR and CT scans that can identify fat in the liver. There are other tests known as FibroScan, which can non-invasively detect stiffness in the liver that would suggest there may be some early scarring.

And of course, the more definitive and invasive way to diagnose NAFLD, which is not done in most patients, is liver biopsy.

But in circumstances where we're concerned about the stage of the disease, or we're not completely convinced that it's NAFLD, then we can do a liver biopsy and look at the tissue under the microscope.