Which of the following is the underlying problem in neurogenic diabetes insipidus?

Correct Answer: E

Rationale: Neurogenic diabetes insipidus is a condition characterized by a deficiency of vasopressin (antidiuretic hormone). Vasopressin is responsible for regulating the body's water balance by controlling the reabsorption of water in the kidneys. In neurogenic diabetes insipidus, there is a problem with either the production, release, or action of vasopressin, leading to excessive urination and thirst. This condition can be caused by damage to the hypothalamus or pituitary gland, which are involved in producing and releasing vasopressin. Symptoms of neurogenic diabetes insipidus include frequent urination, excessive thirst, and dehydration.

Correct Answer: D

Rationale: Neurogenic diabetes insipidus is due to a deficiency in vasopressin (antidiuretic hormone, ADH) production in the hypothalamus or a failure of proper vasopressin release from the posterior pituitary. Causes of neurogenic DI typically involve factors affecting vasopressin synthesis, storage, or release. However, mutations in the vasopressin gene itself would be a cause of genetic forms of diabetes insipidus, not neurogenic diabetes insipidus. Common causes of neurogenic diabetes insipidus include traumatic brain injury, brain tumors, pituitary adenomas, meningitis, and Sheehan's syndrome.

Correct Answer: A

Rationale: Congenital adrenal hyperplasia (CAH) is the most common cause of ambiguous genitalia in newborns. This condition is due to a deficiency of enzymes in the adrenal gland that are necessary for the production of cortisol. As a result, the body produces excess androgens (masculinizing hormones), leading to abnormal genital development in females. The external genitalia may appear ambiguous, with features of both male and female genitalia. This condition can be detected through newborn screening and confirmed through further hormonal and genetic testing. Treatment involves hormone replacement therapy to normalize hormone levels and surgery may be required to reconstruct the genitalia.

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: B

Rationale: Postmenopausal estrogen therapy has been shown to have a protective effect on bone density and reduce the risk of osteoporosis-related fractures, including hip fractures. Estrogen therapy helps to maintain bone strength and reduce the chances of fractures in postmenopausal women. Therefore, estrogen therapy does not increase the risk of hip fractures; in fact, it may decrease the risk of hip fractures in this population.

Correct Answer: C

Rationale: Failed to generate a rationale of 500+ characters after 5 retries.

Correct Answer: A

Rationale: Acromegaly is a hormonal disorder that results from the overproduction of growth hormone (GH) in adulthood. One of the key physical characteristics associated with acromegaly is the enlargement of facial features. People with acromegaly often develop prognathism, which is a condition where the lower jaw protrudes forward, leading to a prominent lower face. Additionally, they may have large fleshy lips due to the soft tissue swelling that occurs as a result of excess GH. Other common signs of acromegaly include enlarged hands and feet, thickened skin, and joint pain.

Correct Answer: A

Rationale: Congenital adrenal hyperplasia does not lead to dwarfism. It is a group of genetic disorders that affect the adrenal glands and can cause various symptoms related to hormone imbalances. In contrast, the other conditions listed - hypopituitarism, homocystinuria, and pseudohypoparathyroidism - can all lead to dwarfism through different mechanisms. Hypopituitarism is characterized by a deficiency of pituitary hormones, including growth hormone, which can result in stunted growth and dwarfism. Homocystinuria is a metabolic disorder that can affect bone growth and lead to skeletal abnormalities resulting in dwarfism. Pseudohypoparathyroidism is a rare genetic disorder that can manifest with short stature or dwarfism due to skeletal abnormalities caused by altered bone metabolism.

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.