Friday 2 May 2014

Endocrine physiology mcqs with answers

1. A person comes to you with an elevated serum free calcium but the parathyroid hormone level (PTH) is in the normal range (52, with a normal in this assay of 15-55). What is the best conclusion?

A. The PTH is normal, therefore the problem does not lie in the parathyroid gland.
B. The person must have excessive sensitivity to PTH, since normal levels are stimulating excessive calcium mobilization from bone.
C. The PTH should be low if the parathyroid were functioning normally, thus the problem does lie in the parathyroid gland.
D. You cannot be sure what is going on; you need to perform a parathyroid scan.





Correct Answer: C






2. A mother comes to see you because two of her seven children are morbidly obese. She and her husband think they may have some relatives in common, and both parents are dark-haired. She brings one of her children with her. The boy is 13 years old, and weighs 230 lb; his BMI is 52. At birth, he was found to have adrenal insufficiency and has been treated with appropriate doses of glucocorticoids. On exam he is an obese, but otherwise normal red-haired kid. What would be the best treatment, assuming that the phenotype is due to a single genetic lesion, and that the treatment options listed were available?
A. Leptin injections.
B. A melanocortin 4 receptor (one of the MSH receptors) agonist.
C. An NPY antagonist.
D. Four weeks in a summer camp for obese kids.
E. Thyroid hormone replacement.




Correct Answer: B






3. You have a brother who has type 1 diabetes. He has had severe hypoglycemia in the past, without warning. Therefore, you have 1 mg of glucagon available for injection in this situation. When you give the glucagon, which of the following will happen?
A. Glycogenolysis and gluconeogenesis will promptly increase.
B. The glucose transporter GLUT4 will translocate to the plasma membrane, causing brain glucose uptake to increase.
C. The tyrosine kinase activity of the glucagon receptor will be turned on.
D. Lipolysis will be suppressed.
E. Nothing, because you have to give some form of glucose along with the glucagon in order for it to work.





Correct Answer: A






4. Which of the following statements is true regarding thyroid hormone receptors (TRs):
A. The three beta isoforms of the thyroid hormone receptor (TR-b1, b2, b3) are the products of three distinct genes
B. The predominant TR isoform in the liver is TR-a1
C. TR-b2 is the major mediator of the negative regulation of the TSH and TRH genes in the pituitary and paraventricular hypothalamus respectively.
D. Uncoupling protein-1 (UCP-1) is an important thyroid hormone target in white adipose tissue that is involved in thyroid hormone induced thermogenesis
E. Increased cholesterol levels that occur in hypothyroidism are the result of upregulation of LDL receptor expression in hepatocytes.





Correct Answer: C






5. Which of the following statements regarding thyroid hormone synthesis is correct?
A. Thyroid hormone is actively transported from the thyrocyte (thyroid follicular epithelial cell) to the circulation by a specific transport protein.
B. The predominant hormone made by thyrocytes is tri-iodothyronine (T3)
C. The synthesis of thyroxine (T4) occurs within the thyrocyte.
D. Thyroid hormone is proteolytically cleaved from thyroglobulin by enzymes acting within the lumen of the thyroid follicle. The released hormone then diffuses from through the thyrocyte and into the circulation.
E. Iodine that is released from proteolytic cleavage of thyroglobulin can be recycled from mono and diiodotyrosines by the action of type I deiodinase enzyme residing in thyroid follicular cells.





Correct Answer: E






6. A 51-year old woman seeks attention because she has not had a menstrual period for 4 months. She is not pregnant, and her follicle stimulating hormone level returns at 112 uIU/dL (normal < 14). She is menopausal and is deficient in estrogen and:
A. Activin
B. Inhibin
C. GnRH
D. Corticosterone





Correct Answer: B






7. In parathyroid cells, calcium regulates expression and release of parathyroid hormone (PTH) by binding to:
A. A nuclear receptor in the supergene family that includes steroid hormone receptors, the thyroid hormone receptor, and a number of "orphan" receptors.
B. A transmembrane protein receptor that activates a G-protein-mediated signal cascade.
C. The golgi bodies where PTH is stored, and stimulating their fusion with exocytotic vesicles.
D. A calcium-binding domain in the extracellular matrix, inducing a structural change in the matrix.
E. A glycoprotein in the gap junction between parathyroid cells, mediating transcytotic calcium flux.





Correct Answer: B






8. A 52-year-old male presents for treatment of his hyperlipidemia. Diet efforts have had little effect on his lipid profile. RISKS: no known coronary artery disease, non-smoker and no family history of early coronary artery disease. Blood pressure 150/94, Lab data shows: total cholesterol 250 mg/dl, TG 250 mg/dl, HDL 34 mg/dl, LDL 166 mg/dl, fasting glucose 135 and 128 mg/dl on two occasions. According to ATP III guidelines:
A. By ATP III guidelines this patient has two risk factors for coronary artery disease.
B. By ATP III guidelines this patient should be treated with medication to achieve an LDL level of less than 160 mg/dL.
C. By ATP III guidelines this patient should be treated with medication to achieve an LDL level of less than 130 mg/dL.
D. By ATP III guidelines this patient should be treated with medication to achieve an LDL level of less than 100 mg/dL.
E. The high TG levels pose the greatest cardiac risk for this patient.





Correct Answer: D






9. On physical examination a patient is noted to have tendon xanthomata. Which statement regarding this patient is true:
A. Lipemia retinalis is often seen in association with this physical exam finding.
B. This patients triglyceride levels are usually elevated.
C. Usually a genetically determined defect in the LDL receptor causes lipid abnormalities associated with this physical finding.
D. The condition is not associated with risk of early coronary artery disease.




Correct Answer: C






10. A deficiency of ACTH secretion would greatly diminish
A. The synthesis of aldosterone
B. The synthesis of testosterone in a man
C. The secretion of cortisol
D. The secretion of estradiol
E. All of the above



Correct Answer: C




11. Cortisol synthesis would be diminished by
A. A defect in 11-hydoxysteroid dehydrogenase
B. A defect in 21-hydoxylase
C. A defect in 18-hydoxylation
D. A defect in 5-alpha-reductase
E. A defect in aromatase




Correct Answer: B





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