Labs 8-13

Question 1

How does GH affect plasma glucose levels?

Answer 1

GH promotes increased blood sugar (counter-insulin effects)

Question 2

Why does GH hypersecretion increase risk of diabetes mellitus?

Answer 2

GH promotes increased blood glucose
hyperglycemia –> hyperinsulinemia
increased risk of insulin resistance and diabetes

Question 3

what are the symptoms of GH hypersecretion?

Answer 3

gigantism, acromegaly (bone thickening), enlargement of hands and feet, protrusion of lower jaw, increased body hair and glucose tolerance

Question 4

describe effects of somatotrope tumor

Answer 4

GH hypersecretion

gigantism, acromegaly –> risk for organomegaly

Question 5

T/F: you can measure GH levels at a certain time to diagnose a defect

Answer 5

FALSE - GH secretion is pulsatile, so pointless to measure at a certain time period. have you observe changes in GH secretion in response to oral glucose administration

Question 6

in normal patients, oral glucose administration should do what to GH levels?

Answer 6

decrease GH secretion

GH promotes glucose secretion so if you take oral glucose, you don’t need GH stimulating more glucose production

Question 7

what is cold intolerance an indicator of?

Answer 7

TRH defect (low metabolism, TSH, T3/T4)

Question 8

how does GH hypersecretion affect TSH production?

Answer 8

GH hypersecretion = Somatostatin increases (it inhibits GH and wants to bring it down) = decreases TSH production

SS inhibits TSH

Question 9

T/F: SS stimulates TSH

Answer 9

FALSE - inhibits

Question 10

Why do patients with pituitary tumors have headaches “behind their eyes”?

Answer 10

pituitary tumor mass enlargens in sella turcica –> vision defects, headache

can impinge on optic chiasma and cranial nerves

Question 11

T/F: acromegaly TYPICALLY associates with hypotension

Answer 11

FALSE - hypertension

Question 12

What is a possible treatment for GH hypersecretion?

Answer 12

SS analogs

Question 13

How do you calculate the expected heigh of a child base on the heights of the parents?

Answer 13

avg the parents and -2.5 if patient is a girl, +2.5 if patient is a boy

Question 14

in normal patients, on the onset of puberty, GnRH will increase what hormones? How will that affect males specifically?

Answer 14

GnRH increases FSH/LH production at the onset of puberty

in males: stimulates testes growth –> testosterone

Question 15

T/F: GnRH secretion is pulsatile

Answer 15

TRUE

Question 16

How would you measure GnRH secretions? (that a patient’s GnRH levels are normal)

Answer 16

Observe changes in FSH/LH levels with an injection of GnRH

Question 17

T/F: prolactin (excessive) stimulates GnRH levels

Answer 17

inhibits

Question 18

what is the clinical significance of decreased GnRH levels during high prolactin? (ex. nursing mothers)

Answer 18

During nursing, mothers have high prolactin that allows for good milking. GnRH (FSH/LH) is decreased to prevent pregnancy (cause having a pregnant nursing mother is bad –> very little nutrition for mom)

Question 19

what is constitutional delay?

Answer 19

physical and sexual maturation delay

Question 20

what disease is indicative of largely increased urine output?

Answer 20

diabetes insipidus

Question 21

what are the urine and plasma osm levels in a patient with diabetes insipidus?

Answer 21

urine: low osm, hypotonic urine, large volume
plasma: high osm, hypernaturemia

Question 22

what is polyuria

Answer 22

increased urine output

as seen in diabetes insipidus

Question 23

how does diabetes insipidus affect heart rate, blood pressure, thirst?

Answer 23

polyuria –> decrease total body water, plasma vol and BP

baroreceptors sense decreased BP –> stimulate SNS to increase HR (tachycardia)

increase thirst (polydypsia)

Question 24

what type of IV fluids should be given to patient with diabetes insipidus?

Answer 24

isotonic dextrose solution

dextrose metabolizes and leaves behind fluids (water) and decrease plasma osm

can also administer synthetic ADH to increase water retention

Question 25

why does prolactinoma decrease menstruation?

Answer 25

increased prolactin = decreased GnRH = decrease FSH/LH –> no periods

Question 26

what treatments can be used for patients with prolactinomas?

what are the 2 examples used in lab?

Answer 26

dopamine (PIF) agonists

ex. bromocriptine
ex. cabergoline (longer half life)

Question 27

T/F: TRH stimulates prolactin

Answer 27

TRUE