Which of the following statements correctly describes the pathophysiology of Cushing's disease?

Correct Answer: A

Rationale: Rationale: A: Correct. Cushing's disease is caused by a pituitary adenoma secreting excess ACTH, stimulating adrenal cortex to produce excess cortisol. B: Incorrect. Cushing's disease does not result from excess cortisol secretion by the pituitary adenoma. C: Incorrect. Cushing's disease is not caused by an adrenal adenoma secreting excess ACTH. D: Incorrect. Cushing's disease is not caused by an adrenal adenoma secreting excess cortisol. Summary: The correct answer is A because it accurately describes the pathophysiology of Cushing's disease, where a pituitary adenoma secretes excess ACTH leading to increased cortisol production. Choices B, C, and D are incorrect as they misinterpret the primary source of hormone overproduction in Cushing's disease.

Correct Answer: A

Rationale: The correct answer is A: Cirrhosis. In cirrhosis, there is a decrease in the binding proteins for T4, leading to decreased total T4 levels in the plasma. Pregnancy, euthyroid sick syndrome, and familial excess thyroid binding globulin are all conditions associated with increased total T4 levels due to various physiological changes. In pregnancy, there is an increase in thyroid hormone production to support fetal development. Euthyroid sick syndrome is a condition where there is a decrease in binding proteins, leading to an increase in free T4 levels but normal total T4 levels. Familial excess thyroid binding globulin causes an increase in total T4 levels due to excessive binding proteins.

Correct Answer: C

Rationale: Elevated glucose levels in obese individuals are often due to insulin resistance. Insulin resistance occurs when the body's cells do not respond effectively to insulin, leading to decreased glucose uptake. This results in elevated blood glucose levels. Diabetic acidosis (choice A) is a complication of uncontrolled diabetes characterized by high blood ketone levels, not directly related to obesity. Glucose intolerance (choice B) refers to the body's inability to regulate blood glucose levels efficiently but is not specific to obesity. Insulin deficiency (choice D) is characteristic of type 1 diabetes, where the body does not produce enough insulin, which is distinct from insulin resistance seen in obesity.

Correct Answer: A

Rationale: The correct answer is A. Visual changes such as double vision, reduced vision, tunnel vision are common symptoms of acromegaly due to the enlargement of tissues in the eye sockets affecting the optic nerve. Paresthesia and weakness in the hands (B) are not typical symptoms of acromegaly but may be seen in conditions affecting the peripheral nerves. Diarrhoea (C) and abdominal distention (D) are not associated with acromegaly but may be seen in gastrointestinal disorders.

Correct Answer: A

Rationale: The correct answer is A: Adrenaline. In injury to the adrenal cortex, adrenaline is least affected because it is primarily synthesized and secreted by the adrenal medulla, not the adrenal cortex. Cortisol, aldosterone, and androstenedione are hormones produced by the adrenal cortex. In adrenal cortex injury, the secretion of cortisol, aldosterone, and androstenedione would be significantly affected due to the damage to the adrenal cortex, leading to hormonal imbalance and related symptoms. Therefore, option A is the correct answer as it is not primarily secreted by the adrenal cortex and would be least affected in this scenario.

Correct Answer: B

Rationale: The correct answer is B: Inhibition of the function of thyroid peroxidase. Propylthiouracil inhibits thyroid peroxidase, an enzyme essential for thyroid hormone synthesis. By blocking this enzyme, propylthiouracil reduces the production of thyroid hormones, helping to manage hyperthyroidism in Graves' disease. Explanation: 1. Propylthiouracil directly inhibits thyroid peroxidase, unlike other antithyroid medications that target different mechanisms. 2. Inhibition of thyroid peroxidase leads to decreased synthesis of thyroid hormones, effectively controlling hyperthyroidism. 3. Other choices are incorrect because propylthiouracil does not primarily affect the production of thyroid-stimulating immunoglobulins (choice A), peripheral conversion of T4 to T3 (choice C), or iodine organification (choice D) in the treatment of Graves' disease. In summary, the inhibition of thyroid peroxidase by

Correct Answer: B

Rationale: The correct answer is B: Dry skin. In hypothyroidism, the thyroid gland does not produce enough thyroid hormone, leading to decreased metabolism. This can result in several symptoms, including dry skin due to reduced sweat gland activity. Hyporeflexia (A) is not a common symptom of hypothyroidism. Oily skin (C) is more commonly associated with hyperthyroidism, where thyroid hormone levels are elevated. Excessive hair growth (D) is not typically seen in hypothyroidism; instead, hair loss is a common symptom.

Correct Answer: A

Rationale: The correct answer is A: Diarrhea. Addison's disease is a condition where the adrenal glands do not produce enough hormones. Diarrhea is not a typical symptom of Addison's disease. The characteristic features include fatigue, weakness, weight loss, dizziness (B), hyperpigmentation, low blood pressure, dehydration (D), and skin changes like dermatitis is common (C). Therefore, diarrhea does not align with the typical symptoms of Addison's disease.

Correct Answer: A

Rationale: The correct answer is A: Acute pancreatitis. Hyperparathyroidism is not typically associated with acute pancreatitis. Hyperparathyroidism is characterized by excessive production of parathyroid hormone, leading to increased calcium levels in the blood. Nephrocalcinosis, palpable neck swelling, and pseudogout are commonly seen in hyperparathyroidism due to the effects of elevated calcium levels on the kidneys, parathyroid glands, and joints, respectively. Acute pancreatitis, on the other hand, is more commonly associated with gallstones, alcohol consumption, or certain medications, rather than hyperparathyroidism.