الفهرس 
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Abstract
Summary
Non-alcoholic fatty liver disease (NAFLD) is one of the most common causes of chronic liver disease worldwide. It is one of the features of metabolic syndrome in obese children and adolescents. Liver biopsy, which is the gold standard for diagnosing NAFLD is an invasive procedure with potential adverse effects.
FibroScan, or transient elastography (TE), non-invasively assesses liver fibrosis and presents comparable performance to liver biopsy to predict liver-related outcomes in patients with chronic liver diseases, including chronic viral hepatitis, NAFLD and its subtype NASH, AIH and primary biliary cirrhosis. Controlled attenuation parameter (CAP) is a novel parameter for detection of hepatic steatosis. TE with CAP is a viable alternative to ultrasonography, both as an initial assessment and during follow-up of patients with NAFLD.
Visfatin is a novel adipokine originally described to be produced predominantly by visceral fat tissue. It also synthesized by bone marrow cells, activated lymphocytes, liver cells, and skeletal muscle cells.
Therefore, we assess the prevalence of hepatic abnormalities in obese children and adolescents by transient elastography using liver stiffness and CAP and evaluate their relation to clinical and laboratory variables as well as serum visfatin levels.
This study included 80 children and adolescents with simple obesity (42 males and 38 females) recruited from the regular attendants of the Pediatric Obesity Clinic, Pediatric Hospital, Ain Shams University. Patients were compared with 40 age- and sex-matched healthy subjects (26 males and 14 females) enrolled as controls. The mean age of obese
Summary
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patients was 9.0 ± 3.1 years (range: 3-16 years) while that of controls was 9.9 ± 3.2 years (range: 5-14 years).
All included patients were subjected to detailed medical history and thorough clinical examination with special emphasis on blood pressure and auxological measures (BMI and waist/hip ratio). Abdominal ultrasound was done for assessment of the liver size in cm, echogenicity, hepatic vasculature and presence of focal lesion or intrahepatic biliary radicles dilatation. Liver stiffness measurements were done for all patients using FibroScan. CAP, a novel physical parameter based on the properties of ultrasonic signals acquired by the Fibroscan machine was assessed.
Laboratory investigations included fasting lipid profile, fastin..g blood glucose and insulin level, liver and kidney functions and coagulation profile. Serum vsiaftin levels were obtained from patients‟ files.
In the current work, weight SDS, BMI SDS, waist and hip circumference SDS as well as waist/hip ratio SDS were higher among patients than controls. As regards laboratory data among obese patients, 16 out of 80 (20%) patients had elevated ALT >42 IU/L and 5 (6.3%) patients had insulin resistance (HOMA IR ≥3.0). The highest incidence of dyslipidemia was observed according to HDL cholesterol <45 mg/dL where 47/80 (58.8%) patients had dyslipidemia.
As regards hepatic abnormalities among the studied obese patients, 16 (20%) patients had elevated ALT, 54 (67.5%) had hepatomegaly and 31 (38.8%) had NAFLD by abdominal ultrasound while 9 (11.2%) had both NAFLD and elevated ALT. It was found that 61.2% of the studied obese patients had NAFLD grade 0 (i.e. normal echogenicity of the liver), 36.2% had NAFLD grade 1 and 2.5% had NAFLD grade 2 while none of the patients had grade 3.
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Transient elastography was performed for all obese patients except one. According to liver stiffness, 81.2% of patients had F0, 12.5 % had F1, 2.5% had F2 and another 2.5% had F3 while none had F4. Using CAP, 43.8% had S0 (no stestosis), 23.8%, 13.8% and 17.5% had S1, S2 and S3, respectively. According to either CAP or elevated ALT, steatosis was observed in 47 patients; only 3 of them had S0 by CAP but their ALT was elevated.
Comparison of demographic data and anthropometric measures among obese patients with or without NAFLD showed that patients with NAFLD had higher age, weight, height SDS, BMI SDS, waist and hip circumference as well as waist/hip ratio compared with those without NAFLD. Obese patients with NAFLD had higher FBG, serum creatinine, ALT, triglycerides, total cholesterol and LDL cholesterol than those without NAFLD.
According to either elevated liver enzymes or CAP values, obese patients were classified into two groups with and without steatosis. Comparison of demographic data and anthropometric measures among the two groups showed higher weight, BMI, waist circumference and waist/hip ratio among those with steatosis. The incidence of dyslipidemia was increased among obese patients with steatosis.
Comparison between obese patients and control group revealed significantly higher serum visfatin levels in patients. Higher visfatin levels were found among patients with NAFLD and/or elevated ALT as well as those with steatosis. Moreover, serum visfatin was gradually increased in relation to NAFLD grades till reaching the highest levels in NAFLD grade II. In addition, increased visfatin levels were associated with significant degree of fibrosis and steatosis being higher in METAVIR score F3 and steatosis stage S3.
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There were significant positive correlations between serum visfatin and each of BMI SDS, waist circumference, waist/hip ratio, ALT, total cholesterol, liver stiffness and CAP.
Liver stiffness was significantly higher in patients with dyslipidemia, heptomegaly, NAFLD, steatosis as well as those with both NAFLD and elevated ALT. It was also elevated in relation to increased grade of NAFLD. With respect to CAP, it was significantly higher in dyslipidemia, NAFLD and/or elevated ALT. ROC curve analysis revealed that liver stiffness cutoff value 4.5 KPa could significantly detect the presence of NAFLD among obese patients with 63.3% sensitivity and specificity of 73.5%.
Liver stiffness and CAP were positively correlated to liver span, serum creatinine, LDL-cholesterol and visfatin levels. In addition, there were positive correlations between CAP and each of ALT and AST. Both liver stiffness and CAP were positively correlated