Alanine aminotransferase and spleno-portal dynamics affect spleen stiffness measured by point shear-wave elastography in patients with chronic hepatitis C in the absence of significant liver fibrosis

Background: Spleen stiffness (SS) has gained a lot of interest in the context of liver cirrhosis and portal hypertension stratification. However, there is a paucity of data on confounding factors that may alter SS values. Methods: Between January 2018 and October 2019, we enrolled 120 healthy subjects and 117 patients with hepatitis C virus (HCV) infection who did not have significant liver fibrosis (i.e., F0–1). Abdominal ultrasound evaluation was performed on each individual to measure portal vein diameter, portal flow velocity, spleen bipolar diameter, and splenic area. We also performed liver and spleen elastography. Results: HCV patients had higher SS (p < 0.001), portal vein diameter (p = 0.031), portal flow velocity (p = 0.035), spleen bipolar diameter (p = 0.042) and area (p = 0.025), and ALT levels (p < 0.001). Linear regression models showed that SS increased by 3.220 kPa for each mm of portal vein diameter, by 0.7 kPa for each cm/s of portal flow velocity, by 2.239 kPa for each cm of spleen bipolar diameter, and by 0.233 kPa for each cm2 of spleen area. Patients with HCV infection were stratified according to median ALT levels (i.e. 32 IU/L). SS and spleno-portal axis parameters were significantly higher in patients with an ALT level > 32 IU/L. Besides, the relationship between SS and ALT was described by cubic polynomial regression according to the following equation: 11.735 + 0.404 (ALT)1 − 0.002 (ALT)2 + 4.26 × 10–6 (ALT)3. Conclusions: Our results bring new light to the role of inflammation as a confounding factor for SS measurement. Therefore, particular attention should be paid to serum transaminase for a correct evaluation of spleen elastography.