الفهرس 
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Abstract
Summary
Androgenetic alopecia (AGA), the most common nonscarring alopecia, is an androgen-induced disorder characterized by hair loss in genetically predisposed men. In AGA, androgens induce miniaturization of hair follicles, especially in the frontotemporal area and vertex of the scalp. AGA patients were found to be more susceptible to cardiovascular diseases, insulin resistance (IR), metabolic syndrome, diabetes mellitus and hypertension.
Insulin resistance (IR) plays a major role in the pathophysiology of metabolic syndrome and hyperinsulinemia is an independent risk factor for coronary artery disease (CAD), wherein it accelerates the development of atherosclerosis and prevents the resorption of atherosclerotic plaque. Association between IR and AGA have been reported and hyperinsulinemia plays a pathogenic role in local androgen production and miniaturization of hair follicles.
Myostatin, known as growth-differentiation factor 8, is a member of the transforming-growth factor beta superfamily, and it is secreted mainly from the skeletal muscle. myostatin is also secreted from adipose tissues and is associated with the regulation of fat mass and insulin sensitivity.
The inhibition of myostatin contributed to the suppression of muscle atrophy and reduced adiposity with improved insulin sensitivity. In addition, serum myostatin levels were elevated along with an increase in the insulin level, independent of skeletal muscle mass, in patients with obesity.
The fundamental controllers of the serum levels of myostatin have not yet be to completely distinguished. Stomach corpulence, androgens and skeletal bulk are the significant segments associated with myostatin amalgamation and delivery. In any case, the systems of the relationship between coursing insulin, glucose levels and serum myostatin have stayed to be completely clarified.
This is the first study to evaluate serum myostatin level in patients with androgenetic alopecia to assess its relation to insulin resistance. This study was conducted on 30 patients suffering from androgenic alopecia (group A). In addition, 20 apparently healthy individuals of matched age and sex as a control group (group B). All patients were selected from the Outpatient Clinic of Dermatology and Andrology Department of Beni-Suef University Hospitals.
Each patient was subjected to full history taking and clinical examination. Serum fasting glucose level was estimated in both androgenic alopecia and control group. Also, serum levels of myostatin and insulin resistance were estimated using ELISA technique in both androgenic alopecia patients and control group. Insulin resistance was estimated by the Homeostasis Model Assessment of Insulin Resistance (HOMA-IR).
In this study:
• HOMA-IR was significantly higher in AGA when compared to control groups. No significant difference was found regarding FBG and insulin between cases and control groups.
• AGA group showed significantly higher myostatin when compared to control group.
• Receiver operating characteristic (ROC) curves of HOMA-IR and myostatin level were conducted for discrimination between AGA cases and control groups. HOMA-IR showed excellent AUC (0.9). At cutoff value of 1.98, sensitivity was 80%, specificity was 90%, PPV was 92.3%, NPV was 75%, and accuracy was 85%. Myostatin showed excellent AUC (0.94). At cutoff value of 256.8, sensitivity was 83.3%, specificity was 90%, PPV was 92.5%, NPV was 89.2%, and accuracy was 86%.
• HOMA-IR increased significantly with higher AGA grades in males and females (p = 0.01 and p < 0.001, respectively). Otherwise, no significant associations were found regarding HOMA-IR level according to other parameters in AGA group (p > 0.05 for each).
• Myostatin level increased significantly with higher AGA grades in males and females. Otherwise, no significant associations were found regarding myostatin level according to other parameters in AGA group (p > 0.05 for each).
• HOMA-IR and myostatin showed significant positive correlation with BMI and AGA grades in both sexes, but not with age, FBG, insulin or duration. Myostatin showed significant positive correlation with HOMA-IR in AGA group.