Test that evaluates liver fat may help prevent nonalcoholic cirrhosis

The so-called non-alcoholic fatty liver disease is a condition that affects around 25% to 30% of the population, according to data from the Brazilian Society of Hepatology.

It is characterized by the accumulation of fat in the liver without association with drinking (alcoholic cirrhosis), whose estimated incidence in the population is 182 cases per 100,000 individuals, according to a survey carried out by Fiocruz in 2008.

Fatty liver can often be found in individuals with the so-called metabolic syndrome, which is characterized by high cholesterol, diabetes, and high blood pressure. In people with obesity, a global epidemiology study of fatty liver (also known as steatohepatitis, or NASH) found an 87% prevalence of NASH in this population.

If left untreated, hepatic steatosis can progress to fibrosis (scarring of liver tissue) and even cirrhosis. At this stage, according to hepatologist João Marcello Neto, cirrhosis is not irreversible, but the patient depends on medication to maintain what doctors call cirrhosis compensation. In some cases, however, the patient may need a liver transplant.

Traditional ultrasound exams make it possible to identify whether the liver is altered in shape, making it possible to assess whether it has fat accumulation or not, but such assessment is limited in terms of the risk of progression of the condition.

The test known as hepatic elastography makes a more accurate analysis of the liver, considering not only the shape but also the texture to assess the stage of the disease. “From 80% to 85% of patients have stage 1, where the risk is still low for cirrhosis evolution, but an average of 10% of patients can reach stage 2 fibrosis and about 5% can progress to cirrhosis “, he explains.

The risk assessment also takes into account several factors such as obesity, high hypertension, type 2 diabetes and dyslipidemia, a condition that can lead to clogged arteries (atherosclerosis). Cardiovascular diseases are the leading cause of death in patients with fatty liver.

The elastography exam is available in the SUS and, since 2018, it has been incorporated into the list of exams of the ANS (National Supplementary Health Agency) with mandatory coverage by health plans. According to Neto, its indication can be made in two conditions, when the presence of fat in the liver has already been identified in traditional ultrasound exams or when the patient is at high risk for deterioration of the condition.

“This active search, as we call it, can bring a benefit to the patient, which is identification at an early stage, before transitioning to phase 2, NASH”, he says.

Fatty liver in its early stages is asymptomatic, so tests are the only way to identify the problem. The doctor points out that the importance of diagnosing fatty liver is because, in its initial stages, it can be resolved with weight loss and lifestyle changes.

The hepatic elastography exam has two stages. The first, called transient elastography, consists of connecting a device to the ultrasound transducer itself that will quantify the stiffness of the liver. Ultrasonic elastographs will assess the texture of fat in the liver.

“The first step is to issue a disturbance at a single point to measure the speed and propagation of the generated waves. It’s like throwing a stone into a lake, which will generate a deformation in the place where it landed. [perturbação] and then the waves formed are measured in terms of intensity and range”, he says.

“In the case of the ultrasonic exam, the waves are external and located at a point in the liver to measure its composition. In the composition we have water, which is a constant factor, and fat is the variable of interest. ‘flick’ in a gelatin to evaluate how this gelatin will respond to the flick, if it is too soft, it will fall off, if it has more resistance, it will return to its original shape quickly”, explains the doctor.

The software, created by pharmaceutical company Novo Nordisk, allows you to calculate up to ten different measurements of the liver. The drugmaker said it seeks to expand the types of devices with this technology in the future.

“Before, it was an exam with an elite character, as it was mainly carried out in the private health network. The metabolic syndrome disease, the main cause of non-alcoholic fatty liver disease, has a higher incidence in the most vulnerable strata of society, and that is why it is so important a quick and effective diagnosis, with expansion to the entire population”, says Neto.