Nokea
Which of the following investigations is the gold standard for diagnosing acromegaly?
- A. Serum IGF1 measurement
- B. Growth hormone releasing hormone measurement
- C. Oral glucose tolerance test + Growth hormone measurement
- D. Growth hormone measurement
Correct Answer: C
Rationale: The gold standard for diagnosing acromegaly is the oral glucose tolerance test (OGTT) along with growth hormone (GH) measurement. During this test, the patient is given a glucose solution to drink, and then blood samples are taken to measure GH levels at specific time intervals. In a person without acromegaly, glucose ingestion would typically suppress GH levels. However, in individuals with acromegaly, GH levels remain elevated even after glucose administration due to the inability of glucose to inhibit GH release from the tumor.
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Increased serum aldosterone level is not associated with:
- A. Hypertension
- B. Hypernatraernia
- C. Hypokalaemia
- D. Metabolic acidosis
Correct Answer: D
Rationale: Increased serum aldosterone level is typically associated with conditions such as Conn's syndrome or primary hyperaldosteronism. These conditions lead to an excess of aldosterone, which results in increased sodium resorption and potassium excretion by the kidneys. This imbalance can lead to hypertension (Choice A), hypernatraernia (elevated sodium level) (Choice B), and hypokalaemia (low potassium level) (Choice C). However, metabolic acidosis (Choice D) is not directly associated with increased aldosterone levels. Instead, metabolic acidosis may be seen in conditions like renal tubular acidosis or diabetic ketoacidosis.
Which age group does acromegaly most commonly affect?
- A. 30-50 years
- B. 10-25 years
- C. 55-70 years
- D. 25-40 years
Correct Answer: A
Rationale: Acromegaly most commonly affects individuals in the age group of 30-50 years. This condition is typically diagnosed in adults between these ages. Acromegaly is often caused by the overproduction of growth hormone in adults, which leads to excessive bone growth and tissue expansion. While acromegaly can develop at any age, it is more commonly seen in adults within the 30-50 age range.
Pseudohypoparathyroidism is not associated with:
- A. Cataract
- B. Raised level of plasma PIH
- C. Mental retardation
- D. Reduced level of plasma phosphate
Correct Answer: B
Rationale: Pseudohypoparathyroidism is a rare genetic disorder that mimics the symptoms of hypoparathyroidism, despite normal or elevated levels of parathyroid hormone (PTH). The condition is characterized by hypocalcemia, hyperphosphatemia, and normal or elevated PTH levels. However, it is not associated with a raised level of plasma PIH (Parathyroid Inhibiting Hormone). In pseudohypoparathyroidism, the body's tissues are resistant to the action of PTH, leading to impaired calcium regulation. Other common features of pseudohypoparathyroidism may include cataract formation, mental retardation, and reduced levels of plasma phosphate.
Which one of the following is acromegaly caused by?
- A. Overproduction of adrenocorticotropic hormone (ACTH)
- B. Overproduction of gonadotrophin releasing hormone (GnRH)
- C. Overproduction of growth hormone (GH)
- D. Overproduction of vasopressin (antidiuretic hormone)
Correct Answer: C
Rationale: Acromegaly is a disorder that is characterized by the overproduction of growth hormone (GH) by the pituitary gland in adults. This results in the abnormal growth of bones and tissues, leading to enlarged hands, feet, and facial features. The excess GH is usually caused by a pituitary tumor known as a somatotroph adenoma. This tumor causes the pituitary gland to produce excessive amounts of GH, which in turn leads to the symptoms associated with acromegaly. Treatment for acromegaly often involves surgical removal or reduction of the pituitary tumor, as well as medication to normalize GH levels.
Aldosterone:
- A. is synthesized in the zona fasciculata.
- B. is deficient in Conn's syndrome.
- C. is independent of ACTH.
- D. is suppressed by elevated potassium.
Correct Answer: D
Rationale: Aldosterone is a hormone produced in the zona glomerulosa of the adrenal cortex, not the zona fasciculata (Choice A is incorrect). Conn's syndrome, also known as primary hyperaldosteronism, is characterized by excess aldosterone secretion, not a deficiency (Choice B is incorrect). Aldosterone production is under the control of the renin-angiotensin-aldosterone system, which is stimulated by factors such as low blood pressure, low blood volume, and high potassium levels. Elevated potassium in the blood directly suppresses aldosterone production by the adrenal glands, serving as a negative feedback mechanism to maintain electrolyte balance (Choice D is correct). The synthesis of aldosterone also requires cholesterol as the precursor, rather than pregnenolone (Choice E is incorrect). Lastly, aldosterone production is regulated in part by ACTH (adrenocorticotropic hormone), as it can enhance the effects of