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: Medullary carcinoma of the thyroid typically presents with symptoms related to the thyroid gland itself, neck mass or swelling, and sometimes cervical lymphadenopathy. It is characterized by the production of calcitonin, leading to high serum calcitonin levels. Carcinoid syndrome, which includes symptoms such as flushing, diarrhea, and wheezing, is more commonly associated with neuroendocrine tumors, rather than medullary carcinoma of the thyroid. Psychosis is not a typical feature or manifestation of medullary carcinoma of the thyroid.

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: Hypoglycemia is characterized by a low blood sugar level, which can lead to various symptoms. The features of hypoglycemia typically include drenching sweat, tachycardia (increased heart rate), and tachypnea (rapid breathing). A brisk jerk, on the other hand, is not a typical feature of hypoglycemia. Symptoms such as confusion, dizziness, shakiness, hunger, weakness, and irritability are more commonly associated with hypoglycemia than a brisk jerk.

Correct Answer: D

Rationale: An Addisonian crisis, also known as an acute adrenal crisis, is a life-threatening medical emergency that occurs due to severe adrenal insufficiency, leading to a sudden drop in cortisol levels. Cortisol is a vital hormone produced by the adrenal glands, and its deficiency can result in serious symptoms such as hypotension, dehydration, electrolyte imbalances, and shock. If left untreated, an Addisonian crisis can be fatal. Therefore, the correct description of an Addisonian crisis is severe adrenal insufficiency resulting in dangerously low serum cortisol levels.

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: D

Rationale: Binding proteins are essential in transporting hormones through the bloodstream and protecting them from rapid degradation by enzymes. These proteins do not actually mediate the hormonal effects themselves. Hormonal effects are typically mediated by the hormone-receptor interactions at target cells. Binding proteins primarily serve as carriers for hormones and maintain their stability and availability in the circulation.

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: C

Rationale: Acromegaly is a disorder caused by excessive growth hormone production after the closure of the epiphyses (growth plates) in bones, leading to abnormal growth of tissues and organs. The following options are associated with acromegaly: