Nokea
Primary hyperaldosteronism is not featured by:
- A. Diastolic hypertension
- B. Paraesthesia
- C. Alkalosis
- D. Oedema
Correct Answer: B
Rationale: Primary hyperaldosteronism, also known as Conn's syndrome, is characterized by excessive production of aldosterone by the adrenal glands, leading to increased sodium reabsorption and potassium excretion in the kidneys. The typical features of primary hyperaldosteronism include hypertension (often systolic), hypokalemia, metabolic alkalosis, and oedema due to sodium retention. Paraesthesia, which refers to abnormal sensations such as tingling or numbness, is not a common feature associated with primary hyperaldosteronism.
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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 of the following lung cancers is most commonly associated with the syndrome of inappropriate secretion of antidiuretic hormone (SIADH)?
- A. Squamous cell carcinoma
- B. Small cell (oat cell) carcinoma
- C. Large cell carcinoma
- D. Adenocarcinoma
Correct Answer: B
Rationale: Small cell (oat cell) carcinoma of the lung is most commonly associated with the syndrome of inappropriate secretion of antidiuretic hormone (SIADH). This paraneoplastic syndrome occurs in patients with small cell lung cancer due to the production of antidiuretic hormone (ADH) by the tumor cells. The excessive release of ADH leads to water retention and dilutional hyponatremia, causing symptoms such as nausea, confusion, seizures, and potentially life-threatening complications. Other types of lung cancer, such as squamous cell carcinoma, large cell carcinoma, and adenocarcinoma, are less commonly associated with SIADH.
Commonest enzymatic defect for development of congenital adrenal hyperplasia is:
- A. C-21 hydroxylase deficiency
- B. 3b dehydrogenase deficiency
- C. C-11 hydroxylase deficiency
- D. C-17 hydroxylase deficiency
Correct Answer: A
Rationale: C-21 hydroxylase deficiency is the most common enzymatic defect leading to the development of congenital adrenal hyperplasia (CAH). This enzyme is necessary for the synthesis of cortisol and aldosterone in the adrenal glands. When there is a deficiency in C-21 hydroxylase, the pathway is shifted towards the production of androgens instead of cortisol and aldosterone, leading to excess androgen production. This results in the characteristic features of CAH, such as ambiguous genitalia in females and virilization in both males and females. Other enzyme deficiencies listed in the choices can also lead to different types of CAH but are less common compared to C-21 hydroxylase deficiency.
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
All of the following are features of Conn's syndrome except:
- A. Alkalosis
- B. Hyperkalemia
- C. Muscle cramps
- D. Severe systemic hypertension
Correct Answer: B
Rationale: Conn's syndrome, also known as primary hyperaldosteronism, is characterized by excess production of aldosterone by the adrenal glands. This leads to increased sodium retention and potassium excretion in the kidneys. As a result, patients with Conn's syndrome typically present with hypokalemia (low potassium levels), not hyperkalemia (high potassium levels). The other features of Conn's syndrome include alkalosis (metabolic), muscle cramps, and severe systemic hypertension.