In the present study, the mean age of NAFLD patients was 45.95 ± 7.2 years which is consistent with NICE guidelines 2018 [4]
This study showed a significant difference in BMI between case and control groups which agrees with Rui et al. [11]. Ghobadi et al. 2014 [12] as well found a significant correlation between BMI and grades of NAFLD, as our study showed a statistically significant difference regarding BMI between grade 1 versus grades 2 and 3.
Concerning blood sugar, this study showed statistically significant difference between case and control groups. This agrees with Zhengjun [13], as impaired hepatic lipid and lipoprotein settling and increased oxidative stress in liver cells may increase liver fat accumulation and result in insulin resistance, this leads to increase in hepatic glucose production and elevated blood glucose [14].
Zhengjun [13] postulated that triglyceride, total cholesterol, and LDL cholesterol in NAFLD group were significantly higher than those in control group, which matches our study, as we found statistically significant differences between case and control groups regarding lipid profile. Furthermore, our study showed that HDL in case group was significantly lower than in control group, but this was not consistent with the study of Zhengjun [13] as there was no significant difference regarding HDL.
This study showed that increasing grade of NAFLD was significantly associated with worse lipid profile, where there were differences between three grades as regard total cholesterol and LDL, there was statistically significant difference between grade 1 and grade 3 in triglycerides and HDL, and between grade 1 and grade 2 in HDL. This agrees with Dhumal et al. [15] who found that increasing grades of NAFLD were significantly associated with increasing serum total cholesterol, LDL, and VLDL and decreasing HDL, yet they found no significant association between serum triglyceride.
Regarding portal vein Doppler indices, this study revealed statistically significant differences between case and control groups in all Doppler indices.
Vmax, Vmin, and VPI in case group were significantly lower than in control group. This was compatible with Besir et al. [16]. Balasubramanian et al. [17], although agreed with our finding regarding Vmax, found no significant difference regarding Vmin.
On comparing 3 grades of NAFLD, this study showed significant decrease in Vmax and VPI with increasing the grade of NAFLD. This agrees with Besir et al. [16] and Balasubramanian [17]. Yet, not with Ehsan et al. [18] who found no significant difference in VPI between fatty liver grades.
Vmin showed significant decrease only on comparing grade 3 versus grades 1 and 2; this agrees with Besir et al. [16] who postulated that Vmin decreased as the degree of hepatosteatosis increased.
MFV in case group was significantly lower than in control group which corresponds with Ehsan et al. [18]. Moreover, MFV was significantly decreasing with increasing NAFLD grade which is consistent with Balasubramanian [17].
These findings regarding velocity of the portal flow and portal vein pulsatility index can be explained by the hypothesis that liver infiltration with fat increases flow resistance in portal vein reducing hepatic portal blood flow [19].
Regarding hepatic artery Doppler, this study revealed that HARI in case group was significantly lower than in control group. This agreed with Claudio et al. [20] and Balasubramanian [17] who agreed also with our finding that HARI was significantly decreasing with increasing NAFLD grade. These findings suggest an increased hepatic artery blood flow which may occur as a compensatory mechanism for reduced portal flow with the progression of hepatic steatosis [21].