Blood Protein Shows Strong Promise for Detecting Fatty Liver Disease

A single blood test measuring a protein released by injured liver cells may offer a simpler way to detect metabolic dysfunction-associated steatotic liver disease, the condition better known as MASLD that has become the leading cause of chronic liver disease worldwide. The protein also tracked the severity of liver fibrosis far more closely than it tracked the amount of fat stored in the liver, suggesting it reflects hepatocellular damage rather than fat accumulation itself.

The study, published in the Egyptian Liver Journal, enrolled 80 participants between October 2024 and June 2025 from outpatient hepatology clinics. Sixty patients with MASLD formed the patient group, while 20 apparently healthy controls were matched to them by age and sex. Every participant underwent a full clinical examination, laboratory testing, and measurement of serum L-FABP using the enzyme-linked immunosorbent assay technique. Patients additionally received abdominal ultrasonography and Fibroscan examinations with controlled attenuation parameter and liver stiffness measurement, while the researchers calculated the Fibrosis-4 index, the NAFLD fibrosis score, and the aspartate aminotransferase to platelet ratio index as established non-invasive fibrosis markers.

MASLD is defined by liver steatosis affecting more than 5 percent of hepatocytes and is typically accompanied by insulin resistance. It belongs to the broader family of steatotic liver disease without substantial alcohol consumption and is linked to one or more cardiometabolic risk factors. The condition spans a spectrum from simple steatosis through metabolic dysfunction-associated steatohepatitis to progressive fibrosis, cirrhosis, and MASH-related hepatocellular carcinoma. Between 25 and 29 percent of people worldwide are estimated to have MASLD, a figure projected to reach 30.7 percent by 2040. North Africa and the Middle East carry the highest regional burden, with an estimated 31.8 percent of people affected, and Egypt ranks among the top ten nations for obesity incidence, although precise national prevalence data for MASLD remain lacking.

Diagnosing the disease currently depends on liver biopsy, which remains the gold standard but carries significant drawbacks. The procedure is invasive and painful, can lead to post-procedure complications, is costly, and is vulnerable to sampling errors during specimen collection and handling. Non-invasive alternatives have gained popularity for diagnosis, progression tracking, and treatment monitoring. Fibroscan, or elastography, measures the stiffness of liver tissue to gauge hepatic fibrosis and offers a reasonably quick and secure detection method, although hepatic inflammation can affect tissue flexibility and produce elevated results. Conventional liver enzymes such as ALT and AST are often raised in MASLD but may remain normal in patients with mild steatosis, making them insufficient on their own. More sophisticated fibrosis indicators including the FIB-4 index and the Enhanced Liver Fibrosis test are used increasingly, yet FIB-4 has weak positive predictive usefulness in communities where advanced fibrosis is uncommon.

L-FABP belongs to a family of small, highly conserved lipid chaperone molecules that show distinct patterns of tissue expression in organs engaged in active lipid metabolism, including hepatocytes, adipocytes, and cardiac myocytes, where fatty acids serve as substrates for lipid synthesis, storage, or breakdown. The liver form participates in hepatic fatty acid oxidation, phospholipid and cholesterol metabolism, and intracellular fatty acid transport, and hepatocytes express it in a gradient that decreases from the portal region of the hepatic lobule toward the center. Prior research had already linked hepatic injury and fibrosis to the protein, reported higher L-FABP levels in MASLD patients, and established serum L-FABP as a reliable biomarker for identifying drug-induced liver injury and as a diagnostic marker for non-alcoholic fatty pancreatic disease. The Egyptian team set out to evaluate its diagnostic utility specifically in Egyptian patients.

The results showed that patients with MASLD carried significantly greater serum L-FABP levels than controls. Liver enzymes were also significantly elevated in the patient group, which additionally exhibited lower serum albumin despite higher total protein, reduced hemoglobin, dyslipidemia, and poor postprandial glucose control. The MASLD group had significantly higher rates of hypertension and diabetes mellitus than the control group, with p-values of 0.022 and 0.030 respectively, although the two groups did not differ significantly in age, sex distribution, weight, height, body mass index, or waist circumference. The absence of a BMI difference contrasts with the traditional view tying fatty liver disease to excess body weight and aligns with growing evidence that MASLD can occur in people of normal weight, a phenotype known as lean MASLD.

Perhaps the most striking finding concerned fibrosis. Most patients had early fibrosis, with 66.7 percent classified as F0 to F1 on Fibroscan and 33.4 percent at F2 to F4, while 75 percent showed moderate to severe steatosis. Patients with severe fibrosis had significantly higher L-FABP levels than those without fibrosis, and mean levels rose steadily across fibrosis stages, from 4.9 plus or minus 0.66 ng/mL at F0 to 10.4 plus or minus 2.5 ng/mL at F4. One-way ANOVA confirmed significant variation across fibrosis grades with F equal to 59.789 and p below 0.001. By contrast, although patients with hepatic steatosis grades S1 to S3 had higher mean L-FABP levels than those without steatosis, the increase did not follow a consistent pattern with steatosis severity, and statistical analysis found no significant correlation between L-FABP and the degree of steatosis, with F equal to 1.51 and p equal to 0.207.

The protein also correlated with established markers of liver injury and fibrosis. L-FABP showed significant positive correlations with ALT and AST, with correlation coefficients of 0.559 and 0.574 respectively, both with p below 0.001, and a significant negative correlation with total protein. No significant correlations emerged with age, BMI, waist circumference, albumin, total bilirubin, or direct bilirubin. Among the fibrosis indices, the FIB-4 score correlated at 0.446, the APRI score at 0.561, and the NAFLD fibrosis score at 0.885, all with p below 0.001, with the last representing a particularly strong association that positions L-FABP alongside existing non-invasive fibrosis assessment tools.

Diagnostic performance proved equally notable. An L-FABP cut-off of 4.05 ng/mL yielded an area under the ROC curve of 0.90 for diagnosing MASLD, with a 95 percent confidence interval of 0.831 to 0.972. Sensitivity reached 95 percent, meaning most MASLD cases were correctly identified, while specificity stood at 50 percent, indicating only a moderate ability to exclude non-MASLD cases. For predicting fibrosis among MASLD patients, a cut-off of 6.5 ng/mL performed even better, with an AUC of 0.963, a 95 percent confidence interval of 0.921 to 1, sensitivity of 95 percent, and specificity of 80 percent.

The authors caution that the study was a single-center case-control design with a relatively small sample size, which may limit generalizability and increase the risk of selection bias. The diagnosis of MASLD and the staging of fibrosis rested on Fibroscan and confirmed non-invasive fibrosis scores rather than liver biopsy, the current gold standard, and differences in metabolic comorbidities between groups may have introduced residual confounding. The cross-sectional nature of the work also precludes conclusions about causal relationships or longitudinal changes in L-FABP levels, and the researchers call for future studies using independent validation cohorts to confirm the cut-off values. Even with those constraints, the findings mark L-FABP as a potential non-invasive biomarker for diagnosing MASLD and evaluating liver fibrosis, one that correlates well with the degree of liver injury and fibrosis but not with the degree of steatosis, and that could eventually help reduce reliance on biopsy in a disease affecting roughly a quarter of the global population.

Subject of Research: Diagnostic utility of serum liver fatty acid-binding protein for metabolic dysfunction-associated steatotic liver disease and liver fibrosis in Egyptian patients

Article Title: Using liver fatty acid binding protein as a diagnostic marker for metabolic dysfunction and associated steatotic liver disease (MASLD) in Egyptian patients: a case-controlled study

Article References: Elbasuony, H. A., Abdelatti, E. A., Abdelsameea, E., Ali Yussef, S. M., Montaser, B. A. E., & Abdalaah, E. M. (2026). Using liver fatty acid binding protein as a diagnostic marker for metabolic dysfunction and associated steatotic liver disease (MASLD) in Egyptian patients: a case-controlled study. Egyptian Liver Journal, 16(1), Article 83. https://doi.org/10.1186/s43066-026-00536-1

Image Credits: AI Generated

DOI: 10.1186/s43066-026-00536-1

Keywords: MASLD, L-FABP, fatty liver disease, liver fibrosis, biomarker, Fibroscan, liver biopsy, ELISA, non-invasive diagnosis, Egypt, FIB-4, case-control study