All the following are risk factors for the development of osteoporotic fractures except

Correct Answer: A

Rationale: While African race is considered a protective factor against the development of osteoporosis due to higher peak bone mass and lower fracture rates compared to other races, the other factors listed (current cigarette smoking, female sex, and physical inactivity) are all established risk factors for the development of osteoporotic fractures. African-American individuals, in general, have a lower risk of osteoporosis and fractures compared to Caucasians and Asians.

Correct Answer: D

Rationale: Weight gain is a common symptom of Cushing's syndrome due to the excessive production of cortisol, a hormone that regulates metabolism and fat storage. The other symptoms listed, such as easy bruising, acne, and stretch marks, are also characteristic features of Cushing's syndrome. However, weight loss is typically not associated with this condition. In fact, individuals with Cushing's syndrome often experience unexplained and rapid weight gain, especially in the face, abdomen, and upper back (resulting in a characteristic "buffalo hump" appearance), rather than weight loss.

Correct Answer: B

Rationale: Sheehan's syndrome, also known as postpartum hypopituitarism, is a condition characterized by pituitary gland dysfunction due to severe blood loss during childbirth, resulting in ischemic necrosis of the pituitary gland. As a consequence of pituitary hormone deficiency, one of the hallmark manifestations of Sheehan's syndrome is persistent lactation despite stopping breastfeeding. This occurs due to inadequate prolactin inhibition, leading to continuous milk production. Other common symptoms of Sheehan's syndrome include fatigue, weight loss, menstrual irregularities, hypothyroidism, adrenal insufficiency, and other pituitary hormone deficiencies. Cardiac failure, fever, and striking cachexia are not typical presentations associated with Sheehan's syndrome.

Correct Answer: D

Rationale: Osteomalacia is a condition in which there is a softening of the bones due to a deficiency in vitamin D or calcium. It is not a cause of hypocalcemia, as it is a result of low levels of calcium in the bloodstream. The other options listed are potential causes of hypocalcemia:

Correct Answer: A

Rationale: The most common cause of Cushing's disease is an ACTH-producing pituitary adenoma. In this condition, the pituitary gland produces excessive amounts of adrenocorticotropic hormone (ACTH), which stimulates the adrenal glands to produce high levels of cortisol. This leads to the signs and symptoms of Cushing's disease, such as weight gain, high blood pressure, and muscle weakness. Adrenocortical adenoma refers to a benign tumor of the adrenal cortex that can also cause Cushing's syndrome, but it is not as common as an ACTH-producing pituitary adenoma. Ectopic ACTH secretion occurs when a non-pituitary tumor produces ACTH, leading to Cushing's syndrome. McCune-Albright syndrome is a rare genetic disorder that can cause various endocrine abnormalities, but it is not a common cause of Cushing's disease.

Correct Answer: D

Rationale: Oxytocin and antidiuretic hormone (ADH; vasopressin) are both synthesized in the hypothalamus, specifically in the supraoptic and paraventricular nuclei. After synthesis, they are transported along axons to the posterior pituitary where they are stored until they are released into the bloodstream when needed. This is why they are released from the posterior pituitary, not the anterior pituitary. These hormones have different functions in the body, with oxytocin being involved in labor and breastfeeding, while ADH plays a role in regulating water balance and blood pressure.

Correct Answer: A

Rationale: Hypertonicity (increased osmolarity or high concentration of solutes in the blood) is the most potent stimulus for the hypothalamic production of arginine vasopressin (also known as antidiuretic hormone or ADH). When the body senses increased plasma osmolality, the osmoreceptors in the hypothalamus stimulate the release of vasopressin from the posterior pituitary gland. Vasopressin acts on the kidneys to increase water reabsorption and decrease urine output, helping to restore normal osmolarity. This mechanism helps to conserve water and maintain body fluid balance in response to dehydration or increased solute concentration in the blood.

Correct Answer: B

Rationale: In males, Leydig cells in the testes are stimulated to produce testosterone by luteinizing hormone (LH). LH is produced by the anterior pituitary gland and acts on the Leydig cells to promote the synthesis and release of testosterone. This hormone plays a crucial role in male reproductive function and the development of masculine characteristics. Follicle stimulating hormone (FSH) plays a role in spermatogenesis in males but does not directly stimulate Leydig cells to produce testosterone.

Correct Answer: D

Rationale: Myxoedema is a severe form of hypothyroidism characterized by a range of symptoms and signs. Ascites, cerebellar ataxia, and increased incidence of pernicious anaemia are recognized features of myxoedema. However, thyroid acropachy is not a recognized feature of myxoedema. Thyroid acropachy is a condition characterized by clubbing of the fingers and toes, swelling of the hands and feet, and periosteal new bone formation, typically seen in patients with Graves' disease, which is a form of hyperthyroidism.