Endocrinology Flashcards

1
Q

Which of these hormones does not use the tyrosine kinase receptor for cell signalling?

  1. Insulin
  2. Growth Hormone
  3. Glucagon
  4. Vascular Endothelial Growth Factor
A

Glucagon

Glucagon acts on Adenyl Cyclase in the hepatic cell membrane resulting in glycogenolysis and the release of glucose.

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2
Q

Which of these hormones does not use the Phospholipase C secondary messenger system?

  1. Parathyroid Hormone
  2. Vasopressin/ADH
  3. Angiontensin II
  4. Thyroxine
A

Thyroxine has receptors within the nucleus and enters the cell by a carrier mediated ATP dependent process.

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3
Q

Which one of these statements regarding Growth Hormone is false?

  1. Its secretion is stimulated by high glucose levels
  2. It stimulates osteoblasts within membranous bones
  3. It stimulates the release of IGF-1 by the liver which is also dependent on adequate concentrations of insulin
  4. It inhibits gluconeogenesis
A
  1. Its secretion is stimulted by high glucose levels

Growth Hormone is stimulated by hpoglycaemia, particularly when severe. It causes gluconeogenesis and is therefore a diabetogenic hormone.

IGF-1 synthesis relies on circulating levels of insulin. Hence low or normal levels can be seen in feline hypersomatotropism with diabetes mellits before insulin therapy is started

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4
Q

Which one of these statements regarding pituitary dwarfs is false?

  1. Pituitary dwarfs have disproportionate growth retardation
  2. They have low circulating levels of GH and TSH
  3. Progestins are a recognised treatment
  4. It is an autosomall recessive inherited abnormality due to a defect in LHX3
A
  1. Pituitary dwarfs have disproportionate growth retardation

Disproportionate growth retardation is seen in congenital hypothyroidism

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5
Q

Which one of these statements regarding calcium homeostasis is correct?

  1. PTH acts directly on osteooclasts to increase blood levels of calcium
  2. Hypervitaminosis D is associated with hypercalcaemia and hypophosphataemia
  3. PTH acts on the DCT to promote reabsorption of Ca/Mg/H+
  4. Tertiary hyperparathyroidism is associated with atrophy of one of more of the parathyroid glands
A
  1. PTH acts on the DCT to promote reabsorption of Ca/Mg/H+

It also decreases absorption of Na/K/amino acids

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6
Q

Which of the following statements on hypothyroidism is false?

  1. It is associated with atrial fibrillation
  2. It is associated with low fructosamine
  3. Carprofen and potentiated sulphonamides can intefere with thyroid testing
  4. Greyhounds have comparatively low circulating thyroid hormones
A
  1. It is associated with low fructosamine

Fructosamine tends to be high due to reduced rate of protein turnover

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7
Q

Which of the following statements regarding medical management of insulinoma is false?

  1. Glucagon can increase insulin secretion as well as promoting glycogenolysis
  2. Streptozocin is hepatotoxic
  3. Octreotide can result in worsening hypoglycaemia
  4. Diazoxide prevents depolarisation of pancreatic beta cells
A
  1. Streptozocin is nephrotoxic

Octreotide is a somatostatin analogue and therefore can inhibit release of GH and glucagon

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8
Q

A cat presents to your clinic with bilateral flank alopecia, PU/PD, and acute onset blindness. You run biochemistry and an ACTH stimulation test. Testing reveals severe hypokalaemia, high creatinine kinase and a subnormal cortisol response to ACTH. What is the most likely diagnosis?

  1. Feline Hypoadrenocorticism
  2. Feline Hyperadrenocorticism and CKD
  3. Feline Hyperaldosteronism and Hyperprogesteronism
  4. Feline Hyperaldosteronism and Hyperadrenocorticism
A
  1. Feline Hyperaldosteronism and Hyperprogesteronism

Hypokalaemia, and HypoKa induced myopathy, hypertension causing blindess are associated with hyperaldosteronism. Need to test plama renin activity alongside serum aldosterone levels to rule out causes of secondary hyperaldosteronism (CKD).

Cats with PHA can have concurrent progesterone excess. This competes with cortisol for glucocorticoid receptors causing signs of HAC. Increased levels of free cortisol in the circulation will then exert negative feedback on ACTH secretion.

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9
Q

Which one of these statements regarding aldosterone is false?

  1. Release is stimulated by hyperkalaemia
  2. Release is stimulated by angiontensin II
  3. Atrial Natriuretic Peptide reduces its secretion
  4. It is broken down by 11 Beta-hydroxysteroid dehydrogenase
A
  1. It is broken down by 11 Beta-hydroxysteroid dehydrogenase

11B-HSD-1 activates cortisol
11B-HSD-2 breaks down cortisol (inhibited by eating too much licorice!)

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10
Q

Which of the following ketone bodies is not detected by the urine dipstick?

  1. Acetoacetate
  2. Beta-hydroxybutyrate
  3. Acetone
  4. Beta-hydroxyacetate
A

Beta-hydroxybutyrate

Acetoacetate and acetone (spontaneous breakdown product of acetoacetate) are detected.
Beta-hydroxyacetate does not exist

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11
Q

Which of the following hormones is produced by adipocytes?

  1. Cholecystokinin
  2. Ghrelin
  3. Glucagon-like peptide-1
  4. Leptin
A
  1. Leptin

CCK: from I-cells in the duodenum
Ghrelin: gastric mucosa, but also found in hypothalamus, pituitary gland, hippocampus, brain cortex, adrenal gland, intestine, pancreas
Glucagon-like peptide-1: L-cells of the distal ileum and colon

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12
Q

Which of the following statements regarding GH and IGF-1 is true?

  1. IGF-1 are usually increased in newly diagnosed diabetic animals
  2. Hypothyrodism can cause an increase of IGF-1
  3. Pasireotide can be use in dogs affected by acromegaly
  4. GH has two function: rapid anabolic and slow catabolic
A
  1. Hypothyrodism can cause an increase of IGF-1
  2. IGF-1 are usually increased in newly diagnosed diabetic animals = False, it i usually reduced (liver required insulin to produced IGF-1)
  3. Pasireotide can be use in dogs affected by acromegaly= false. It can be used in cats affected by acromegaly
  4. GH has two function: rapid anabolic and slow catabolic= false. Rapid catabolic (hyperglicemia) and slow anabolic.
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13
Q

Which hormone is usually not lacking in dwarf german shepherd dogs?

  1. GH
  2. TSH
  3. ACTH
  4. Prolactine
A
  1. ACTH
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14
Q

Which one of the following statements about vasopressin (ADH or AVP) is CORRECT?

  1. ADH and oxytocin are peptides of similar structures.
  2. ADH reduces the permeability of the collecting ducts to urea.
  3. Glucocorticoids stimulate release of ADH, leading to thirst, but inhibit the action of ADH,
    leading to polyuria.
  4. In the presence of ADH, the osmolarity of the tubular fluid within the distal and collecting
    tubules is lower compared to the osmolarity in the Bowman’s space.
A
  1. ADH and oxytocin are peptides of similar structures
  2. n the presence of ADH, water volume is avidly resorbed in the distal tubule and thus urea becomes highly concentrated, generating a large driving force passive urea resorption. As discussed above, the presence of ADH also renders the medullary collecting ducts highly permeable to urea.
  3. higher
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15
Q

Which of the following breed has physiologically lower concentration fo T4

  1. Sighthound
  2. Golden Retrievers
  3. English setter
  4. Rottweiler
A
  1. Sighthound
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16
Q

Which of the following is the CORRECT mechanism of action of streptozocin:

  1. inhibit closure of K+ channels in the B-cells
  2. stimulate closure of K+ channels in the B-cells
  3. binds to somatostatin receptors
  4. destroys B-cells
A
  1. destroys B-cells.

all except for 2. are used for trmt of INSULINOMA.

  1. This is the mechanism of action of DIAZOXIDE (decrease insuline)
  2. This is the mechanism of action of SULFONILUREA (Glipizide) for treatment of diabetes (opposite effect) (–> increase insulin)
  3. This is the mechanism of action of OCTREOTIDE (for dogs) and PASIREOTIDE (for cats)
17
Q

Which of the following glucose channel is insulin-DEPENDENT:

  1. GLUT1
  2. GLUT2
  3. GLUT3
  4. GLUT4
A
  1. GLUT4 (found in fat, muscle and heart)

all the others are insuline INDIPENDENT.

  1. GLUT1 is in erythrocytes
  2. in kidneys, liver and brain
  3. brain , very high affinity for glucose, so that the brain is never left without
there are also SGLUT1  (sodium-glu) in small intestine 
and SGLUT2 (sodium-glu) in the proximal convoluted tubule
18
Q

Which of the following statement about calcium is INCORRECT

  1. if stored for too long, the decrease in pH due to lactic production will increase the calcium levels
  2. if stored for too long, the decrease in pH due to lactic production will decrease the calcium levels
  3. if the tube is left open, the loss of CO2 will increase the pH and decrease the calcium levels.
  4. EDTA contamination would result in decrease calcium levels.
A
  1. if stored for too long, the decrease in pH due to lactic production will decrease the calcium levels” FALSE.

I try to remember that if the pH goes up, the Ca goes down and vice-versa.

19
Q

Which of the following statements regarding ADH is CORRECT

  1. It is synthesized in the supraoptic nucleus of the hypothalamus
  2. V1 receptors are found in the kidneys
  3. V2 receptors are found in the vasculature
  4. the release is stimulated by a decrease in osmolarity.
A
  1. It is synthesized in the supraoptic nucleus of the hypothalamus: correct
  2. V1 receptors are found in the kidneys. FALSE.
    V1 in vasculature –> vasoconstriction (that’s why called vasopressin)
  3. V2 receptors are found in the vasculature FALSE .
    V2 in distal convol tub and collecting duct –> Acquaporin 2 on luminar surface –> more H20 reabsorption (Acquaporin 4,5 used to move H2O from tubular cell to blood).
  4. the release is stimulated by a decrease in osmolarity. FALSE. it is the opposite. stimulated by increase in osmolarity.
20
Q

Which of the following statements regarding PTH is CORRECT

  1. An increase in calcaemia inhibits the release of PTH vesicles
  2. A decrease in calcaemia inhibits the release of PTH vesicles
  3. PTH is formed in the oxyphil cells of the parathyroid
  4. PTH is increased with liver disease.
A
  1. An increase in calcaemia inhibits the release of PTH vesicles –> correct
  2. A decrease in calcaemia inhibits the release of PTH vesicles. FALSE
  3. PTH is formed in the oxyphil cells of the parathyroid. FALSE. procuded by chief cells. Oxyphil cells not clear what they do.
  4. PTH is decreased with liver disease. FALSE. Just invented it :P and Google told me PTH might be lower with liver disease.
21
Q

The thyroid hormones (choose the correct)

  1. are circulating bound mostly to tranthyreting
  2. are circulating bound mostly to albumin
  3. are circulating bound mostly to throxine binding globulin
  4. decrease the activity of the 2Na/2K pump in cells.
A
  1. are circulating bound mostly to throxine binding globulin. correct. 70% bound to TBG.
  2. are circulating bound mostly to transthyretin. FLASE. only 15% more or less
  3. are circulating bound mostly to albumin. FALSE. only 15% more or less
  4. decrease the activity of the 2Na/2K pump in cells. FALSE. T3 increase the activity of the Na/K pump increasing metabolism rate, heat production, ATP consumption and size and number of mitochondria.
22
Q

Which of the following is NOT a STIMULUS for the production/release of PROLACTIN

  1. dopamine
    2 TRH
  2. Estrogen
  3. Breast feeding
A
  1. Dopamine CORRECT. secreted by hypothalamic arcuate nucleus, dopamine inhibits the relaese of prolactine.

all of the following are stimuli for the release of prolactine
2 TRH
3. Estrogen
4. Breast feeding

23
Q

Which of the following is NOT a stimulus for the release of CRH

  1. IL-1 IL-6 TNFalfa
  2. ADH
  3. Somatostatin
  4. Ag II
A
  1. Somatostatin inhibits the release of CRH (as inhibits almost everything)

all the others are stimuli for the release of CRH

  1. IL-1 IL-6 TNFalfa
  2. ADH
  3. Ag II
24
Q

Which of the following statements is true regarding hyperadrenocorticism (HAC)?

  1. Urine cortisol:crea ratio is the test of choice for screening
  2. Low dose dexa supp test is the test of choice for screening
  3. ACTH stim test is the most sensitive test
  4. ACTH stim test can distinguish between adrenal and central HAC
A
  1. Urine cortisol:crea ratio is the test of choice for screening CORRECT. almost 100% sensitivity (good to rule out)
  2. Low dose dexa supp test is the test of choice for screening FALSE. is the test of choice for confirming.HAC. Good specificity (good to rule in)
  3. ACTH stim test is the most sensitive test. FALSE. has got high specificity (as LDDST; good to rule in) but sensitivity varies from 60% for adrenal to 80% for central HAC.
  4. ACTH stim test can distinguish between adrenal and central HAC. FALSE. you can distinguish the 2 by using - LDDST (central will have 4h-post cortisol levels below 1.4 mg/dl; 4h-post drop of 50% from basal; 8h-post cortisol above 1 mg/dl) - endogenous ACTH concentrations (high ACTH –> central; low ACTH –> adrenal)