Optimal ALT Threshold for Automated Diagnosis of MASLD: A Population-Based Study Using iLFT

Introduction

Early diagnosis of metabolic dysfunction-associated steatotic liver disease (MASLD), particularly with advanced fibrosis, is crucial due to the increased risk of complications and mortality. Serum alanine aminotransferase (ALT) is commonly used for this purpose; however, many patients with normal ALT ranges (<55 U/L) may remain undetected. This study investigates the clinical implications of a lower ALT cut-off (>30 U/L) using intelligent liver function testing (iLFT) to identify MASLD patients with and without advanced fibrosis in primary care.

Methods

All patients entering the iLFT diagnostic pathway underwent liver aetiological screening if ALT >30 U/L. The study compared the proportions of MASLD patients with and without advanced fibrosis at different ALT thresholds: 31−41 U/L, 42−54 U/L, and ≥55 U/L.

Results

Between March 2016 and April 2022, 16,373 patients underwent iLFT. Among them, 762 (5%) had MASLD with abnormal fibrosis scores, while 908 (6%) had MASLD with normal fibrosis scores. Of the 428 patients assessed in liver clinics, 169 (39%) had evidence of fibrosis. Specifically, 22 (13%) had ALT 31−41 U/L, 31 (18%) had ALT 42−54 U/L, and 116 (69%) had ALT ≥55 U/L. Among those with advanced fibrosis or cirrhosis, 20 (14%) had ALT 31−41 U/L, 28 (19%) had ALT 42−54 U/L, and 97 (67%) had ALT ≥55 U/L.

Discussion

33% of MASLD patients with advanced fibrosis or cirrhosis had ALT 31−54 U/L, who would have been missed using the conventional ALT range. This suggests that lowering the ALT cut-off improves the diagnosis of MASLD with advanced fibrosis in primary care.

Conclusion

Lowering the ALT threshold to 30 U/L in the iLFT algorithm significantly improves the detection of MASLD patients with advanced fibrosis or cirrhosis in primary care. This approach ensures early diagnosis and timely intervention, potentially reducing the risk of complications and mortality associated with advanced liver disease.

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