Abstract
Objective To provide an update on the most recent developments regarding diagnosis and outcomes of steatotic liver disease (SLD), review new nomenclature applied to SLD, and provide an approach to the diagnosis and management of SLD.
Sources of information Individual articles published mainly in the past 2 years, found using PubMed and Google Scholar.
Main message Steatotic liver disease is one of the most common diseases encountered in general practice. This condition is an important biological marker for metabolic syndrome. Diagnosis relies on noninvasive tests. Known complications of metabolic syndrome and advanced liver disease are often present at the time of diagnosis. Courses of action should include assessment of cardiometabolic risk factors and progressive liver dysfunction. Subtle differences are present among patients diagnosed with SLD. Practitioners should be aware of a flux in terminology of SLD. Management of SLD can be guided using a simple algorithm.
Conclusion There is a need for evaluation of the SLD epidemic and its systemic nature, along with associated independent risk factors of cardiovascular disease as well as metabolic conditions such as dyslipidemia, hypertension, and type 2 diabetes.
At present, 3 interrelated pandemics are occurring: These are obesity,1 type 2 diabetes (T2D),2 and steatotic liver disease (SLD).3 Steatotic liver disease occurs in 32% to 39% of the world’s population4,5 and many cases will be seen first by family physicians. As SLD can occur with or without metabolic syndrome or obesity, this has led to a reappraisal of clinical evaluation and management of the spectrum of SLD.
Sources of information
This review is based on literature searches in PubMed and Google Scholar, and on individual relevant articles (many from the past year; individual articles believed to be relevant and quoted in recent articles were evaluated). In this review we present 3 cases with different courses of management based on new definitions of SLD and SLD’s systemic nature. Specific therapeutic management as well as pediatric SLD will not be discussed.
Cases
Case 1. A 44-year-old man presents for evaluation, complaining of some right upper abdominal and epigastric discomfort for the past 6 to 8 months. On examination, his blood pressure is 154/92 mm Hg, he is 170 cm tall, and his weight is 89 kg. His body mass index (BMI) is 31 kg/m2. Findings of an abdominal examination are normal, but the abdomen is protuberant. He consumes 3 to 4 alcoholic drinks during the week and a few more on the weekend. He smokes 5 to 10 cigarettes a week. Findings of an abdominal ultrasound scan show moderate SLD. Blood test results show increased triglyceride levels of 3.5 mmol/L (normal level <1.7 mmol/L), a fasting blood glucose level of 5.4 mmol/L (normal level <5.6 mmol/L), and a hemoglobin A1c level of 5.5% (normal level <5.7%). His alanine aminotransferase (ALT) level is 41 U/L (normal <35 U/L), aspartate aminotransferase (AST) level is 36 U/L (normal range 8 to 33 U/L),
-glutamyl transpeptidase (GGT) level is 75 U/L (normal <40 U/L), and platelet count is 246×109/L (normal range 150×109/L to 450×109/L).
Case 2. A 50-year-old woman presents for an annual health evaluation. She complains of fatigue but is otherwise well. She denies alcohol consumption. Her height is 167 cm and weight is 77 kg. Her BMI is 27 kg/m2. Blood test results show an increased triglyceride level of 3.6 mmol/L, her high-density lipoprotein level is normal, and her fasting blood glucose level is 16 mmol/L. Her ALT level is 47 U/L, AST level is 39 U/L, GGT level is 39 U/L, and platelet count is 217×109/L. The presence of elevated liver enzyme levels prompts an abdominal ultrasound scan. This reveals a normal biliary tree with moderate SLD.
Case 3. A 34-year-old Asian man presents with dyspepsia. He denies substantial alcohol intake or smoking. Medical evaluation includes normal physical examination findings with a BMI of 22.9 kg/m2. Blood test results show a normal blood glucose level and hemoglobin A1c level, and a triglyceride level of 1.7 mmol/L but otherwise no dyslipidemia. His ALT level is 38 U/L, AST level is 20 U/L, and GGT level is 43 U/L. Viral serology results for hepatitis B and C viruses are negative. Other markers of liver disease are normal. An abdominal ultrasound scan shows moderate SLD. Findings of an upper gastrointestinal barium study are normal.
Main message
Changing nomenclature for SLD. A development in SLD is the change in nomenclature. The first proposed change was by Eslam et al to include metabolic causes for more accurate terminology; therefore, nonalcoholic fatty liver disease was renamed metabolic dysfunction–associated fatty liver disease.6 However, since the term fatty liver may lead to stigmatization, other new names have been considered. A group of expert participants using the Delphi method outlined the most recent proposal for nomenclature.7 The name steatotic liver disease was selected to replace fatty liver disease. Metabolic dysfunction–associated fatty liver disease was changed to metabolic dysfunction–associated steatotic liver disease (MASLD), which is defined as the presence of hepatic steatosis in conjunction with 1 cardiometabolic risk factor and no other discernible cause. The concept of steatohepatitis was retained and when it is related to MASLD it is called metabolic dysfunction–associated steatohepatitis (MASH). The consumption of substantial amounts of alcohol (>140 g to 340 g per week for women and >210 g to 420 g per week for men) associated with metabolic syndrome has been termed metabolic-associated alcoholic liver disease (MetALD), which is the overlap of the above 2 conditions. High consumption of alcohol (quantities exceeding 340 g per week for women and 420 g per week for men) irrespective of its association with metabolic dysfunction is still termed alcoholic liver disease (ALD). The third category of SLD is defined when a specific pathogenesis leads to steatosis. The absence of metabolic or other causes is defined as cryptogenic SLD. The final category of SLD is SLD with a specific pathogenesis such as infection, medication, monogenic disease, or other cause. These terms are compared in Table 1,7-10 and Box 1 outlines definitions of cardiometabolic risk factors.7
Three sets of terms used in the literature to refer to SLD
Definitions of cardiometabolic risk factors as described in the proposed new nomenclature for SLD
If a patient has at least 1 of 5 of the following risk factors, they meet the criteria for MASLD in adults based on the multisociety Delphi consensus statement.7
BMI ≥25 kg/m2 (≥23 kg/m2 in Asia); WC >94 cm in men or >80 cm in women; or ethnicity-adjusted equivalent
Fasting serum glucose level ≥5.6 mmol/L; 2-h postload glucose level of ≥7.8 mmol/L; hemoglobin A1c ≥5.7%; T2D; or prescribed treatment for T2D
Blood pressure of 130/85 mm Hg or a prescribed specific antihypertensive drug treatment
Plasma triglyceride level ≥1.70 mmol/L or prescribed lipid-lowering treatment
Plasma HDL-C level ≤1.3 mmol/L or prescribed lipid-lowering treatment
BMI—body mass index, HDL-C—high-density lipoprotein cholesterol, MASLD—metabolic dysfunction–associated steatotic liver disease, SLD—steatotic liver disease, T2D—type 2 diabetes, WC—waist circumference.
Diagnosis of SLD and further evaluations of disease course. There are several causes of SLD outlined in Box 2.7,11 The criterion standard for diagnosis of SLD is liver biopsy findings of more than 5% fat, but biopsy is done only when the diagnosis or extent of disease is not clear.12 It is safer and more practical to evaluate SLD with noninvasive tests such as biomarker tests and imaging.13,14 While computed tomography scanning and magnetic resonance imaging can detect fat, the most practical imaging test is abdominal ultrasound scanning, but the liver needs to be at least 20% fat for it to be recognized.15
Common secondary causes of metabolic dysfunction–associated steatotic liver disease
Obesity and other metabolic conditions (dyslipidemia, type 2 diabetes)
Extensive weight loss from gastric bypass or jejunoileal bypass
Total parenteral nutrition
Celiac disease (especially when treated with a gluten-free diet)
Genetic causes (glycogen storage disease, abetalipoproteinemia, etc)
Alcohol consumption
Medications such as amiodarone, diltiazem, steroids, tamoxifen, or antiretroviral treatment
Hepatitis C virus infection
The stage of liver fibrosis can be determined with vibration-controlled transient elastography (VCTE) or ultrasound-dependent shear-wave elastography. Liver stiffness measurement (LSM), irrespective of the technique used, provides prognostic information for compensated advanced chronic liver disease (cACLD). The fibrosis index score can be helpful when LSM is measured at baseline and at follow-up. For example, a VCTE measurement of less than 10 kPa rules out cACLD; however, values greater than 15 kPa are highly suggestive of cACLD.16,17 The controlled attenuation parameter (CAP) is a noninvasive measurement that can be measured at the same time VCTE or shear-wave elastography is performed to quantify liver fat (the level must be at least 10%). Results are closely correlated with biopsy findings.8,18 Therefore, the CAP is helpful for assessment, grading, and monitoring the effects of an intervention for liver steatosis.
In addition, a number of noninvasive biomarker tests have been developed to provide follow-up information on the effectiveness of interventions. The ultrasound-dependent fatty liver index and nonalcoholic steatohepatitis index are mentioned in the literature, but are too complex for daily office use.14,19 The most practical validated estimation tool for determining the extent of liver disease is the Fibrosis-4 (FIB-4) score.20 This formula estimates fibrosis based on age, platelet count, and AST and ALT levels (the calculator can be found at https://www.hepatitisc.uw.edu/page/clinical-calculators/fib-4). It should be noted that about half of patients with SLD can have normal liver enzyme levels.21
The FIB-4 score indicates whether liver stiffness should be further evaluated. The cutoff FIB-4 score should be 1.3 (ie, a score <1.3 indicates advanced fibrosis) for patients between the ages of 35 and 65 years.22 Above age 65 a cutoff of 2 was found to be more accurate due to declining AST levels with age.23
A FIB-4 score of less than 1.3 has a 99% negative predictive value in the absence of T2D. In patients with T2D there may be an 11% to 14.5% false-negative rate.24 Its positive predictive value, however, is only 17% for advanced fibrosis (defined as more than stage 2 fibrosis on histopathology19). Therefore, patients with low scores can be followed in the office, with repetition of liver enzyme level tests after 1 year. The FIB-4 score frequently overestimates the risk of fibrosis in patients with higher BMI, older age, and T2D, all factors that are associated with higher liver stiffness on elastography.25,26 Obesity may predict a worse long-term prognosis in those with MASLD.27 A FIB-4 score above 2.67 is strongly correlated with advanced fibrosis and requires hepatology consultation.
In cases where the patient’s FIB-4 score is between 1.3 and 2.67, measuring liver stiffness is important for proceeding with management, since most pharmacologic interventions are based on patients with advanced liver disease.28 Although this calculated score can be used to determine the course of treatment, elastography is somewhat more sensitive and specific for advanced fibrosis.9
The spectrum of SLD. The most common types of SLD are MASLD, MetALD, and ALD. Steatotic liver disease is now recognized as the hepatic manifestation of metabolic syndrome. Similarly, isolated SLD eventually leads to metabolic syndrome. Thus, MASLD may precede or follow complications such as T2D, hypertension, and cardiovascular and nonhepatic neoplasms.10,29 Additionally it poses a risk of progressive liver disease.30
Most cases of MASLD are associated with obesity or overweight status. Initial work suggested that in Asia SLD may occur without obesity or overweight status,31 but more recently it has been reported that about 40% of patients globally are not obese and 20% are lean.4,32 Presence of the patatin-like phospholipase domain–containing protein 3 gene, which promotes cirrhosis and hepatocellular carcinoma, may be found more often in patients without obesity and SLD.33 This and other genes have been found that may help explain why certain ethnic groups (eg, Hispanic populations) have a higher incidence of SLD.34,35 Of note, cryptogenic SLD may not be caused by these genetic markers.7
In a recent study from the United States in 7367 participants, 34.2% were estimated to have SLD based on LSM. Most were men (almost 60%) and about 63% were non-Hispanic white. Of the SLD group 31.3% had MASLD and 2% and 0.7% had MetALD and ALD, respectively.36
The full spectrum of liver disease can be seen in MASLD. The natural history of MASLD encompasses progression from simple steatosis to MASH and progressive fibrosis and cirrhosis. In MASLD the amount of alcohol consumed is not enough to cause disease (<30 g alcohol [3 drinks/day] for men and <20 g [2 drinks/day] for women).7 However, even moderate alcohol consumption may increase risk of disease progression.37 A Swedish study suggested that at least 17% of patients with MASLD consume substantial amounts of alcohol, which dramatically increases risk of decompensation.38 This appears to be much higher than in the previously mentioned study from the United States and may be due to variation in definitions of substantial alcohol consumption.36 The 20% to 30% of patients with MASH can have their disease progress to cirrhosis and its complications, including hepatocellular carcinoma, even without cirrhosis. End-stage MASLD is becoming the most common reason for liver transplant in Western societies.39
Importance of SLD as a systemic disease. As part of the metabolic syndrome it is not surprising that MASLD is associated with comorbidities that may be dependent on or independent of liver disease. In a longitudinal US study of white participants followed for 30 years, MASLD was independently associated with increased all-cause mortality, as were obesity, hypertension, and sedentary lifestyle. However, SLD was also associated with increased cardiovascular events and cancer deaths.40
Patients with obesity (BMI ≥30 kg/m2) and SLD as well as 2 features of metabolic syndrome or T2D were considered to have different risk patterns from patients with obesity only (ie, no T2D and only 1 feature of metabolic syndrome).41 Such “healthy” MASLD patients made up about 7% of a study group41; their mortality rate, cardiovascular disease prevalence, and cancer risks were similar to those in the non-MASLD group. However, these participants were more often male, younger, and had statistically lower BMIs than “unhealthy” patients (with ≥2 features of metabolic syndrome) with obesity. Their status could deteriorate with time, leading to metabolic syndrome.41
A recent meta-analysis by Chan et al evaluated the systemic nature of MASLD.42 The analysis found that MASLD was associated with outcomes such as cardiovascular disease, coronary artery disease, stroke, and heart failure, but not myocardial infarction. Similarly, higher rates of hypertension; chronic kidney disease; gallstones; and colorectal, esophageal, stomach, and thyroid cancers, but not breast and pancreatic cancers, were related to MASLD. Diabetes was positively correlated with increasing fibrosis.
Guide to diagnosis and courses of action to follow. The cases in this review are typical of patients presenting to an office. Statistically SLD is likely to be associated with metabolic dysfunction43 but other causes need to be ruled out in every case. In practice, alcohol use as a cause should be ruled out using a number of available instruments.44,45 However, as noted, the combination of metabolic cause and alcohol intake still indicates the patient is at risk of both diseases. In case 1 there is a reasonable likelihood that alcohol consumption is contributing to liver abnormalities and the pain may well be related to excess fat in the liver (SLD). In case 2, overweight status with dyslipidemia could be playing a role. The patient’s FIB-4 score is 1.31, which is borderline for possible advanced disease. Case 3 represents a patient who is relatively lean even by Asian standards (an overweight BMI is ≥25 kg/m2). However, this scenario may not be uncommon.
In all 3 cases full workup of liver enzyme levels, including alkaline phosphatase, bilirubin, GGT, ALT, AST, and albumin, should be obtained. Viral studies for hepatitis B and C infection, antinuclear antibody levels, ferritin level, and ceruloplasmin level should be obtained. Dyslipidemia and T2D should be ruled out and a hemoglobin A1c level should be obtained. A biomarker for heavy alcohol consumption has been described (ie, phosphatidylethanol): At a cutoff level of 20 ng/mL, this marker identifies moderate or heavy consumption in the past 3 to 4 weeks.46 While the first 2 cases have potential cardiac and nonhepatic cancer risks, all the cases have a risk of hepatic disease progression that needs to be addressed. Furthermore, advancing age or presence of T2D (note the FIB-4 score is less reliable for predicting fibrosis stage) with chronic SLD increases both hepatic and some nonhepatic disease risks.47 The FIB-4 score is useful for classifying risk in all 3 cases.
A 2-stage fibrosis risk-stratification model using FIB-4 has been proposed. This course of action for liver follow-up is outlined by Shaheen et al48 and a very good algorithm is provided by Alberta Health Services.49 A simplified version of this algorithm starting with established SLD is provided in Figure 1.49,50
Algorithm for management of SLD: This simplified outline suggests a course of action based on a diagnosis made by abdominal ultrasound scan, beginning with the recognition of a fatty liver. It should be noted that SLD and liver disease advancement may occur without increased liver enzyme levels. Liver enzyme levels, age, and platelet count are used to calculate the FIB-4 score. In Quebec, referral for VCTE or SWE requires consultation with a gastroenterologist or hepatologist.
Conclusion
While SLD is now usually associated with metabolic syndrome, a considerable number of cases are associated with alcohol consumption. Family physicians need to understand that MASLD is associated with substantial comorbidities that may be independent of liver disease but may advance liver disease complications. When in doubt, refer to a hepatologist.
Notes
Editor’s key points
▸ Steatotic liver disease (SLD) occurs in 32% to 39% of the world’s population, reflecting an epidemic associated with obesity.
▸ Diagnosis of SLD is based on imaging, of which ultrasound is the most readily available and practical. Findings of SLD should alert physicians to the likely presence of cardiometabolic risk factors including dyslipidemia, hypertension, obesity, pre- or overt diabetes, and possibly high alcohol consumption. In addition hepatic and nonhepatic neoplasms occur more often in patients with SLD.
▸ In this approach to the diagnosis and follow-up management of SLD and metabolic dysfunction–associated SLD, new terminology is discussed, which is important for use in therapeutic trials as well as in diagnosis.
▸ The simple Fibrosis-4 score should be used to guide further hepatic management.
Footnotes
Contributors
Dr Andrew Szilagyi was responsible for conceptualizing the review, carrying out a literature search, and writing the manuscript. Dr Nir Hilzenrat contributed to the literature review and to writing the manuscript. Both authors reviewed the manuscript and approved the final version.
Competing interests
None declared
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This article has been peer reviewed.
La traduction en français de cet article se trouve à https://www.cfp.ca dans la table des matières du numéro d’avril 2025 à la page e56.
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