CSGD Quiz 4 2010

1

A 23 year-old pregnant woman is involved in a motor vehicle accident and sustains a fracture of the base of the skull, which has resulted in the pituitary stalk being divided. No other damage has been sustained and the hypothalamic-hypophyseal blood vessels are not affected. Which one of the following is most likely?


  She will be shown to have no growth hormone response to insulin induced hypoglycaemia.

  Her plasma cortisol level will be low.

  Her prolactin level will be increased to levels higher than those normally seen in pregnancy.

  She will not labour unless given an infusion of oxytocin.

  She will be thirsty and her urine output will be in excess of 5 litres per day.

2

Which one of the following hormones does not interact with a cell surface receptor?


  Insulin.

  Cortisol.

  Adrenaline.

  Glucagon.

  Adreno-corticotrophic hormone.

3

Which one of the following human hormones is not a glyco-protein consisting of both alpha- and beta- subunits?


  Follicle-stimulating hormone (FSH).

  Luteinizing hormone (LH).

  Thyroid stimulating hormone (TSH).

  Prolactin (PRL).

  Chorionic gonadotrophin (HCG).

4

Which one of the following features of thyrotoxicosis is specific for Graves’ disease?


  Heat intolerance.

  Resting tachycardia.

  Increased appetite.

  Nervousness and irritability.

  Exophthalmos.

5

Hypothyroidism can be due to all of the following mechanisms except


  Insufficient functioning thyroid parenchyma due to inflammatory destruction.

  Insufficient functioning thyroid parenchyma following the administration of radioactive iodine.

  Pharmacological treatment with lithium.

  Increased TSH synthesis by the pituitary.

  Autoimmune antibody blockade of TSH receptors.

6

Six weeks after thyroid surgery a patient is noticed to have a hoarse voice. Damage to which one of the following nerves at the time of the surgery is most likely to be the cause of this symptom?


  The superior laryngeal nerve.

  The internal laryngeal nerve.

  The external laryngeal nerve.

  The recurrent laryngeal nerve.

  The vagus nerve.

7

TSH exerts its effects by stimulation via the TSH receptor. Which one of the following statements regarding the TSH receptor is correct?


  Antibodies to the TSH receptor lead to stimulation of the thyroid in Graves’ disease.

  During pregnancy increased levels of prolactin can cross react with the TSH receptor and cause self limited thyroid overactivity.

  An excess of circulating TSH causes a short-lived reduction in thyroid hormone action.

  The major effect of the antithyroid drug Carbimazole (Neomercazole®) is to block binding of TSH to its receptor.

  TSH binding to the TSH receptor is via zinc fingers in the thyroid response element.

8

A 2 year old boy presents with early pubic hair development, an enlarged penis, tall stature and over- developed muscles for his age. His testes are of normal size for a boy of two. His older sister was born with ambiguous genitalia. Which one of the following statements about this boy is correct?


  He has central (true) precocious puberty.

  An androgen-secreting adrenal tumour is likely in this case.

  He has the severe salt-wasting form of 21-hydroxylase deficiency.

  He should be treated with hydrocortisone for life.

  His bone age will be delayed.

9

Which one of the following statements is not correct?


  Adrenaline is synthesized by the enzymatic modification of tyrosine in adrenal chromaffin cells.

  Testosterone is synthesized by the action of mitochondrial and microsomal cytochrome P450 enzymes acting on cholesterol in the testis.

  Thyroxine is synthesized by the iodination of tyrosine residues in thyroglobulin and released by proteolysis by the thyroid follicular cells.

  ACTH is synthesized by enzymatic processing of a pre-pro-hormone precursor synthesized on ribosomes in the adrenal cortical zona glomerulosa cells.

  Melatonin is synthesized by the enzymatic modification of tryptophan in the pineal gland.

10

Which one of the following descriptions of Sestamibi is correct?


  It is a radio-labelled antibody that helps to diagnose auto-immune thyroid diseases.

  It is used with CT imaging to diagnose hyperfunctioning adenomas of the adrenal medulla.

  It is used with nuclear medicine imaging in the evaluation of single or multiple thyroid nodules.

  It is an ultrasound contrast agent that assists in the diagnosis of hyperparathyroidism.

  It is used with nuclear medicine imaging to identify the location of parathyroid tumours.