Nokea
Which of the following tests should be used to make the diagnosis of Cushing's syndrome?
- A. 24-hour urine free cortisol
- B. Corticotropin-releasing hormone (CRH) level at 8 a.m.
- C. Inferior petrosal venous sampling
- D. Overnight 1-mg dexamethasone suppression test
Correct Answer: D
Rationale: The overnight 1-mg dexamethasone suppression test is commonly used as an initial screening test for Cushing's syndrome. In this test, a patient takes 1 mg of dexamethasone orally at 11 p.m., and their serum cortisol level is measured the next morning. In patients with Cushing's syndrome, the cortisol levels will not be suppressed by the dexamethasone due to the presence of excessive cortisol production.
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The triad of hyponatraemia, haemodilution and urine hypertonic to plasma suggest diagnosis of:
- A. Nephrotic syndrome
- B. SIADH
- C. Nephrogenic diabetes insipidus
- D. Addison's disease
Correct Answer: B
Rationale: The triad of hyponatremia (low sodium levels in the blood), haemodilution (increased plasma volume), and urine hypertonic to plasma (high urine osmolality compared to blood osmolality) is characteristic of Syndrome of Inappropriate Antidiuretic Hormone (SIADH). In SIADH, there is excessive release of antidiuretic hormone (ADH), also known as vasopressin, leading to water retention by the kidneys and dilutional hyponatremia. This condition results in the body holding onto water, causing hyponatremia and dilution of the blood. The urine being hypertonic compared to plasma indicates that the kidneys are reabsorbing water effectively and concentrating the urine.
Commonest cause of 'ambiguous genitalia' in newborn is:
- A. Congenital adrenal hyperplasia
- B. True hermaphroditism
- C. Testicular ferminisation syndrome
- D. Pseudo-hermaphroditism
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.
The posterior pituitary stores and secretes _________.
- A. anti-diuretic hormone (ADH) and oxytocin.
- B. growth hormone and thyroid-stimulating hormone.
- C. estrogen and testosterone.
- D. aldosterone and cortisol.
Correct Answer: A
Rationale: The posterior pituitary gland secretes anti-diuretic hormone (ADH) and oxytocin, which are produced in the hypothalamus and then transported and stored in the posterior pituitary before being released into the bloodstream. ADH, also known as vasopressin, helps regulate water balance in the body by controlling the reabsorption of water in the kidneys. Oxytocin, on the other hand, plays a role in various reproductive functions such as labor and lactation, as well as social bonding and behavior.
Oxytocin:
- A. is not produced in males.
- B. inhibits lactation.
- C. stimulates smooth muscle contraction.
- D. is produced primarily in the SON in the hypothalamus.
Correct Answer: C
Rationale: Oxytocin is a hormone that is produced in both males and females. In females, oxytocin plays a crucial role in various physiological processes, notably during labor and childbirth. Oxytocin acts on the smooth muscles of the uterus, causing them to contract during labor (parturition) and helps in the ejection of milk during breastfeeding. This hormone is primarily synthesized in the paraventricular nucleus (PVN) and the supraoptic nucleus (SON) of the hypothalamus and stored in the posterior pituitary gland before being released into the bloodstream. Overall, oxytocin's main function is to stimulate smooth muscle contraction in the uterus and the mammary glands.
Which one of the following statements is true regarding the prevalence of acromegaly?
- A. Acromegaly affects a similar number of men and women
- B. Acromegaly affects twice as many women than men
- C. Acromegaly affects twice as many men than it does women
Correct Answer: C
Rationale: Acromegaly is a rare hormonal disorder where excess growth hormone is produced, leading to the enlargement of bones and tissues. The prevalence of acromegaly is higher in men compared to women, with a ratio of about two men affected for every woman. This gender difference is believed to be due to the impact of sex hormones on the development and progression of the condition. While acromegaly can affect both men and women, men are more commonly diagnosed with the disorder.