Nokea
All the following are risk factors for the development of osteoporotic fractures except
- A. African race
- B. Current cigarette smoking
- C. Female sex
- D. Physical inactivity
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.
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Which of the following are not causes of neurogenic diabetes insipidus?
- A. Sheehan's syndrome
- B. Mutations in the vasopressin (ADH) receptor gene
- C. Meningitis
- D. Mutations in the vasopressin gene
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.
What is the most common cause for the overproduction of growth hormone in acromegaly?
- A. Hypothalamic lesion
- B. Hyperplasia of the pituitary stalk
- C. Pituitary lesion
- D. Pituitary adenoma
Correct Answer: D
Rationale: Acromegaly is typically caused by the overproduction of growth hormone (GH) by the pituitary gland. In around 95% of cases, this overproduction is due to the presence of a non-cancerous tumor called a pituitary adenoma. These adenomas are benign, slow-growing tumors that cause the pituitary gland to produce excessive amounts of growth hormone, leading to the characteristic symptoms of acromegaly such as enlargement of the bones and soft tissues.
Cushing's syndrome does not give rise to:
- A. Hirsutism
- B. Peripheral neuropathy
- C. Purple striae
- D. Acne
Correct Answer: B
Rationale: Cushing's syndrome is a disorder caused by prolonged exposure to high levels of cortisol hormone. While Cushing's syndrome can manifest with a variety of symptoms, peripheral neuropathy is not a typical feature of this condition. Cushing's syndrome is commonly associated with symptoms such as hirsutism (excessive hair growth), purple striae (skin stretch marks that are purple in color), and acne due to the hormonal imbalances it creates. Peripheral neuropathy, which involves damage to the peripheral nerves leading to symptoms like numbness, tingling, and weakness in the extremities, is not a characteristic symptom of Cushing's syndrome.
Which one of the following statements describes the underlying pathology of Grave's disease?
- A. An autoimmune disease directed against thyroid stimulating hormone (TSH) receptors. The autoantibodies stimulate the TSH receptors causing increased T3 and T4 production.
- B. Inflammation of the thyroid gland due to lymphocytic infiltration causes the stored thyroid hormones to be released into the circulation leading to hyperthyroidism.
- C. Consumption of ground beef which has been contaminated with thyroid tissue. The thyroid tissue contains metabolically active thyroid hormones which causes hyperthyroidism.
- D. A benign tumour of the thyroid gland which produces excessive amounts of thyroid hormones.
Correct Answer: A
Rationale: Graves' disease is an autoimmune disorder where autoantibodies, known as thyroid-stimulating immunoglobulins (TSIs) or thyroid-stimulating antibodies (TSAs), bind to and stimulate the thyroid-stimulating hormone (TSH) receptors on thyroid follicular cells. This leads to increased production and secretion of thyroid hormones T3 (triiodothyronine) and T4 (thyroxine), causing hyperthyroidism. The autoantibodies essentially mimic the action of TSH, resulting in excess thyroid hormone release and manifestation of hyperthyroid symptoms. This underlying pathology of Graves' disease is distinct from other causes of hyperthyroidism, making choice A the correct statement.
Which of the following hormones are produced in the anterior pituitary gland?
- A. Oxytocin
- B. Prolactin
- C. Adrenocorticotrophic hormone (ACTH)
- D. Follicle-stimulating hormone (FSH)
Correct Answer: D
Rationale: Follicle-stimulating hormone (FSH) is one of the hormones produced in the anterior pituitary gland. The anterior pituitary gland secretes several hormones that regulate various functions in the body. FSH plays a crucial role in both males and females. In females, FSH stimulates the growth and maturation of ovarian follicles, which contain the eggs. In males, FSH is essential for the production of sperm in the testes. The production and release of FSH are regulated by the hypothalamus and gonadotropin-releasing hormone (GnRH).