Nokea
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.
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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.
Thyroid-stimulating hormone (TSH):
- A. is synthesized in parafollicular cells
- B. is a template for thyroid hormone biosynthesis.
- C. is derived from iodinated tyrosine residues.
- D. secretion is inhibited by TRH from the hypothalamus.
Correct Answer: D
Rationale: Thyroid-stimulating hormone (TSH) is a hormone produced by the anterior pituitary gland. It stimulates the thyroid gland to produce and release thyroid hormones, specifically thyroxine (T4) and triiodothyronine (T3). TSH secretion is regulated by the hypothalamus via the release of thyrotropin-releasing hormone (TRH). TRH acts on the anterior pituitary gland to stimulate the production and release of TSH. Therefore, TSH secretion is indeed inhibited by TRH, not stimulated as in the other options.
Which of the following is not a recognized feature of myxoedema?
- A. Ascites
- B. Cerebellar ataxia
- C. Increased incidence of pernicious anaemia
- D. Thyroid acropachy
Correct Answer: D
Rationale: Myxoedema is a severe form of hypothyroidism characterized by a range of symptoms and signs. Ascites, cerebellar ataxia, and increased incidence of pernicious anaemia are recognized features of myxoedema. However, thyroid acropachy is not a recognized feature of myxoedema. Thyroid acropachy is a condition characterized by clubbing of the fingers and toes, swelling of the hands and feet, and periosteal new bone formation, typically seen in patients with Graves' disease, which is a form of hyperthyroidism.
Increased gonadal production of oestrogen is seen in:
- A. Third trimester of pregnancy
- B. Congenital adrenal hyperplasia
- C. Polycystic ovarian disease
- D. Testicular feminization syndrome
Correct Answer: C
Rationale: Polycystic ovarian disease, also known as polycystic ovary syndrome (PCOS), is a common endocrine disorder characterized by increased levels of androgens (male hormones) and disrupted estrogen production in the ovaries. The hormonal imbalance seen in PCOS leads to increased gonadal production of estrogen. This condition is often associated with symptoms such as irregular menstrual cycles, infertility, acne, and excess facial or body hair growth. In contrast, the other options do not typically involve increased gonadal production of estrogen as seen in PCOS.
Which of the following does the adrenal cortex produce?
- A. Adrenaline
- B. Aldosterone
- C. Cortisol
- D. Noradrenaline
Correct Answer: B
Rationale: The adrenal cortex is the outer region of the adrenal glands and is responsible for producing several hormones, including aldosterone. Aldosterone is a mineralocorticoid hormone that plays a crucial role in regulating electrolyte balance, particularly sodium and potassium, in the body. It helps maintain blood pressure and fluid balance by acting on the kidneys to reabsorb sodium and water while excreting potassium in the urine. Adrenaline and noradrenaline (also known as epinephrine and norepinephrine) are produced by the adrenal medulla, which is the inner region of the adrenal glands. Cortisol is another hormone produced by the adrenal cortex, but aldosterone specifically regulates electrolyte balance.