Non-Alcohol Related Fatty Liver Disease (NAFLD)
People are more likely to have fatty liver disease or NAFLD if they have metabolic syndrome, or a different combination of individual component disorders. Obesity, or central abdominal obesity, is a key component disorder of metabolic syndrome.
Obesity, defined as body mass index (BMI) >30, is a useful measure of whether someone is a healthy weight for their height. Central abdominal obesity indicates an increased waist circumference above 94cm in men and 80cm in women. Obesity increases the risk of Type 2 diabetes meillitus. It can also be associated with physical morbidities, sleep apnoea, and infertility.
Other component disorders of metabolic syndrome include insulin resistance or diabetes mellitus, high blood pressure, and an abnormal blood lipid/ fats profile.
Patients with NAFLD could develop progressive liver damage without any warning symptoms, from liver fibrosis (some scarring) to cirrhosis (the most severe form of scarring). The onset of specific symptoms such as jaundice often signifies established chronic or end stage liver disease, and the liver is unable to repair itself.
There are very few symptoms specific to fatty liver disease, which may include vague discomfort in the upper right abdomen.
The first step involves differentiating alcohol related fatty liver disease (ArFLD) from NAFLD. Other causes of abnormal LFTs or another liver disease should be excluded.
Alcohol factor or misuse should be excluded in the diagnosis of NAFLD. The recommended limits in UK are less than 14 units per week for women and less than 21 units for men. See Alcohol Change UK’s unit calculator.
When assessing fatty liver disease, elevated liver enzymes (cell proteins) on blood tests may suggest steatohepatitis (fatty liver with inflammation) but they cannot determine the exact extent of the damage.
The aim of NAFLD assessment are 1) to look for evidence of steatohepatitis and 2) to accurately determine the stage of any liver fibrosis or cirrhosis.
The presence of liver inflammation in NAFLD is known as Non-Alcohol related Steatohepatitis (NASH). The subgroup of patients with NASH has an increased risk of progressive liver damage to cirrhosis through the stages below:
Liver enzyme blood tests lack specificity to diagnose or assess the stage for liver damage/ scarring. Normal LFTs do not exclude liver scarring.
A liver biopsy is very useful to diagnose steatohepatitis and stage for any liver fibrosis. However, non invasive blood tests or scoring systems are clearly preferable.
There are currently no routinely performed blood tests or biomarkers to diagnose or grade the severity of any liver inflammation in NAFLD. Inflammation is the key mediating process towards liver scarring.
The pragmatic approach involves the use of a scoring system based on clinical parameters and blood results, or a specialised scan, to look for liver fibrosis (the actual damage). The examples include:
- NAFLD fibrosis score
- Enhanced Liver Fibrosis (ELF®) blood test
- Transient elastography (Liver fibroscan®)
The upper and lower cut off score for these tests identify those patients with minimal liver fibrosis at most, or advanced fibrosis/ cirrhosis, respectively. This avoids the need for a liver biopsy. These tests can be repeated at regular intervals, for monitoring at-risk patients (those with NAFLD and metabolic syndrome risk factors).
Patients with test scores within the indeterminate range, i.e. between the upper and lower cut off, are assessed further and considered for a liver biopsy.
Healthy lifestyle measures, particularly aerobic exercise, can reduce the amount of fat in the liver. Weight loss of 7 - 10% has been shown to improve NASH. However, healthy lifestyle measures are not always easy to implement or successful.
There is as yet no effective medication that treat or change the natural history of NAFLD/ NASH. Obesity as the common risk factor for NAFLD and metabolic syndrome is the focus of intervention. Orlistat is a medication that can be used to help weight loss in obesity. Other drugs are used for the individual component(s) of metabolic syndrome associated with NAFLD.
The management of obesity has a better chance of success with a specialist weight loss management team – Tier 3 multidisciplinary weight management service in UK. This involves a multi-component lifestyle programme focussing on the promotion of physical activity, a healthy diet, and behavioural change.
Surgical intervention (bariatric surgery – Tier 4 service) for obesity should be considered when all appropriate non-surgical measures have been tried. NICE guideline in UK recommends assessment of the patients who have a BMI of 40 kg/m2 or more, or those who have a BMI 35- 40 kg/m2 and other significant disease (e.g. Type 2 diabetes mellitus) that could be improved if they lost weight.
Intragastric Balloon (IGB)
Intragastric Balloon (IGB) treatment could be an additional option to a lifestyle support programme to induce short term weight loss. Whilst there are potential side effects of nausea or vomiting particularly in the beginning, it is generally well tolerated. The temporary IGB option (6 to 12 months) should be complemented by weight loss maintenance strategies post balloon removal to avoid weight regain.
The IGB option may be particularly helpful for the obese patients with NAFLD who already have associated metabolic syndrome components, but have not met the body mass index (BMI) threshold for surgical intervention.
Specialist Endoscopies and more . . .