Table 1.

Circulating levels of Sirt4 in the study population according to gender, obesity-related morbidities, cardiometabolic indices, HS, and major lifestyle factors.

Parameters		Circulating levels of Sirt4 (ng/mL) n = 43
		Median (min–max)	p value
Gender	Males	0.37 (0.10–2.75)	0.406
	Females	0.68 (0.11–5.56)
Hypertension	Yes	0.15 (0.10–0.42)	<0.001
	No	1.22 (0.11–5.56)
Hypercholesterolaemia	Yes	0.28 (0.11–2.51)	0.015
	No	0.24 (0.10–5.56)
Hypertriglyceridaemia	Yes	0.28 (0.11–2.39)	0.018
	No	1.30 (0.10–5.56)
HDL cholesterol	<cutoff	0.18 (0.10–1.26)	<0.001
	>cutoff	1.88 (0.16–5.56)
Type 2 diabetes	Yes	0.15 (0.10–1.11)	0.001
	No	0.97 (0.11–5.56)
VAI	>cutoff	0.29 (0.10–2.66)	<0.001
	<cutoff	3.23 (1.22–5.56)
HS	Grade 1 (mild)	3.79 (1.33–5.56)
	Grade 2 (moderate)	2.80 (1.66–3.42)	0.007
	Grade 3 (severe)	0.24 (0.18–0.37)
Current smokers	Yes	0.16 (0.10–1.22)	0.001
	No	1.26 (0.11–5.56)
Physical activity	No	0.29 (0.10–2.51)	0.001
	Yes	2.75 (0.11–5.56)
Alcohol consumption	Yes	1.94 (0.10–3.42)	0.190
	No	0.38 (0.11–5.56)

Circulating levels of Sirt4 were lower in individuals with obesity-related comorbidities, adiposity dysfunction, HS, current smokers, and physically inactive individuals. As HoMA-IR and FLI were increased in all the study population, these variables were not included in this analysis. Circulating levels of Sirt4 were significantly different in the presence of obesity-related comorbidities, adiposity dysfunction, HS, and among current smokers or physically inactive individuals, while there were no significant differences according to gender and alcohol consumption. Results are expressed as median plus range according to variable distributions evaluated by Kolmogorov-Smirnov test. Differences between two groups were analyzed by Mann–Whitney U test. Differences among HS grades were analyzed by the Kruskal-Wallis rank test followed by Bonferroni post hoc test. A p value in bold type denotes a significant difference (p < 0.05). Hypertension was defined as SBP ≥ 140 mmHg or DBP ≥ 90 mmHg on two different occasions or taking antihypertensive medication. Hypercholesterolemia was defined as a fasting blood total cholesterol level ≥ 190 mg/dL or use of lipid-lowering medication, hypertriglyceridaemia was defined as fasting blood triglyceride levels ≥ 150 mg/dL or use of lipid-lowering medication, and low HDL cholesterol was defined as <40 mg/dL in men and <50 mg/dL in women [17]. A history of using oral hypoglycemic agents or a type 2 diabetes was diagnosed according to American Diabetes Association (ADA) criteria [18]. Age-specific VAI cut-off values were used according to Amato et al. [8, 25]. In detail, cutoffs in subjects aged ≤30, 31–42, 43–52, and 53–66 years were 2.52, 2.23, 1.92, and 1.93, respectively [8, 25]. The classification of “bright liver” or HS was based on the following scale of hyperechogenicity: grade 0 = absent, grade 1 = light, grade 2 = moderate, and grade 3 = severe, pointing out the difference between the densities of the liver and the right kidney [26]. Subjects smoking at least one cigarette per day were considered current smokers. Physical activity levels were expressed according to whether the participant habitually engaged at least 30 min/day of aerobic exercise. Among alcohol consumers, heavy alcohol consumption was defined as more than two standard drinks per day, which is equal to a daily intake of <30 g of alcohol for men and <20 g of alcohol for women. Sirt4: sirtuin 4; HDL: high-density lipoprotein; VAI: visceral adiposity index; HS: hepatic steatosis.