Which of the following is the most common sign of Cushing's syndrome?

Correct Answer: C

Rationale: The correct answer is C: Purple skin striae. This is the most common sign of Cushing's syndrome due to the excessive production of cortisol leading to thinning of the skin and formation of purple stretch marks. Hirsutism (A) is excessive hair growth, not specific to Cushing's. Obesity (B) can be a symptom, but it is not the most common. Skin hyperpigmentation (D) is seen in Addison's disease, not Cushing's.

Correct Answer: C

Rationale: The correct answer is C: Glucose-6-phosphatase deficiency. This enzyme is essential for gluconeogenesis and glycogenolysis, so its deficiency leads to fasting hypoglycemia. Galactosaemia (A) can cause hypoglycemia due to impaired galactose metabolism. Insulinoma (B) results in excess insulin production causing hypoglycemia. Systemic carnitine deficiency (D) can lead to hypoglycemia by impairing fatty acid oxidation, but it does not directly cause fasting hypoglycemia as seen in Glucose-6-phosphatase deficiency.

Correct Answer: C

Rationale: Erythropoietin is primarily secreted from the kidney, specifically by the Juxtaglomerular cells in the kidney's cortex. These cells are responsible for sensing oxygen levels and regulating erythropoietin production accordingly. Mesenchymal tumors, cerebellar haemangioblastoma, and lymphoma are not associated with erythropoietin secretion, making them incorrect choices. Mesenchymal tumors originate from connective tissues, cerebellar haemangioblastoma is a type of brain tumor, and lymphoma is a cancer of the lymphatic system. Only the Juxtaglomerular cells in the kidney have the physiological role of secreting erythropoietin in response to hypoxia.

Correct Answer: C

Rationale: The correct answer is C: Neovascularization. Non-proliferative diabetic retinopathy is characterized by early changes such as retinal vascular microaneurysms, blot hemorrhages, and cotton-wool spots. Neovascularization is a feature of proliferative diabetic retinopathy, not non-proliferative. Neovascularization refers to the growth of abnormal new blood vessels in the retina, which can lead to severe vision loss if not treated promptly. In summary, neovascularization is not consistent with non-proliferative diabetic retinopathy, as it is a hallmark of the proliferative stage.

Correct Answer: C

Rationale: Step-by-step rationale: 1. Anorexia nervosa can affect both males and females. 2. Therefore, it is not exclusively in females. 3. Hypokalaemia, primary amenorrhea, and low FSH and LH are commonly associated with anorexia nervosa. 4. Choice C is incorrect as anorexia nervosa can affect individuals of any gender.