الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Obesity has become an epidemic with negative health consequences. However, its impact on bone has always been controversial. It was originally thought that obesity has positive impact on bone while some recent data has shown that there has some increased incidence of some fractures due to the poor metabolic environment of obesity.
There has been much interest in the physiology of Wnt pathway and its inhibitor sclerostin. The role of Wnt and sclerostin in bone metabolism has attracted the attention of many studies. Sclerostin is a negative impact on bone structure and a mutation in the SOST gene which is responsible for its production causes sclerosteosis, a high bone mass disease. A recent application of sclerostin is the development of monoclonal anti-sclerostin antibodies which show a promising role in the treatment of osteoporosis. Moreover, sclerostin has been regarded as a biomarker for bone metabolism and it was studied in many physiological as well as pathological conditions.
The present study is a case-controlled study aiming at investigating the connection between obesity and bone metabolism through the link of the recently discovered bone biomarker, sclerostin. The sample was divided into three groups based on BMI; obese, overweight and normal groups. Each participant was subject to complete history and clinical examination including anthropometric measurements. A venous blood sample was withdrawn from each subject and fasting serum glucose, fasting serum insulin, serum sclerostin and serum 25(OH)D together with lipid profile. The results were tabulated and statistically analysed.
The results have shown that sclerostin was significantly lower in obese group versus the overweight and the control groups. Sclerostin had a significant negative correlation with BMI. A possible explanation for this finding is the effect of mechanical loading in the obese subjects on the osteocytes. Various studies have shown that expression of sclerostin decreases by the effect of mechanical loading and increases by unloading. The results have also shown a positive correlation between insulin resistance, measured as HOMA-IR and sclerostin, which indicates that the metabolic complication of obesity is associated with worse bone structure. 25(OH)D was shown to have significant positive correlation with sclerostin, while it had significant negative correlation with obesity and its metabolic complications; insulin resistance and dyslipidaemia.
This study highlights the importance of mechanical loading as an important player in bone metabolism among obese subjects. Moreover, it opens the door for more studies to investigate how insulin resistance cross-talks with bone metabolism. Last but not least, it shows that sclerostin has a very auspicious role not only as a bone biomarker but also as an important physiological regulator of bone metabolism making it the centre of scientific research in bone physiology.