Hypothalamus / pituitary tutorial notes

Question 1

what do disorders relating to the hypothalamus / pituitary usually present with?

Answer 1

• symptoms of excess or deficiency with one or more of the hormones they produce
• other symptoms may be neurological - eg headache or visual disturbances (remember optic chiasm)

Question 2

what are the 5 main causes of hypothalamic/pituitary disorders?

the 5 I’s

Answer 2

• idiopathic - ie no cause
• invasion - ie tumour
• Infarction - death of tissue
• Iatrogenic - caused by surgery, drugs etc
• Injury - ie head trauma

Question 3

what is sheehans syndrome and what symptoms can it cause?

Answer 3

• a condition resulting from damage to the pituitary gland due to low levels of oxygen (by blood loss) during child birth
• can cause difficulty in breast feeding and failure to menstruate after delivery

Question 4

what are the 3 main types of investigations that can be done in order to diagnose someone?

Answer 4

• basal blood tests
• dynamic tests
• imaging

Question 5

if a hormone is stimulated but levels do not rise, what might be the problem?

Answer 5

a problem in the production of the hormone

Question 6

if an inhibiting substance is given, but normal negative feedback does not occur, what is likely to be the problem?

Answer 6

it is likely that there is a hormone - producing tumour causing the symptoms

Question 7

what are the 3 main forms of treatment?

Answer 7

1. replacement hormones - for defiency problems
2. surgery or radiotherapy - for tumours
3. drugs that inhibit production - ie when surgery isnt suitable

Question 8

what is agromegaly?

Answer 8

caused by hypersecretion of GH in adults, usually due to a pituitary tumour

Question 9

in children, what is agromegaly normally referred to as?

Answer 9

gigantism

Question 10

what are the main clinical symptoms of agromegaly?

Answer 10

• enlarged hands and feet
• enlarged skull circumference
• enlarged liver, kidneys and heart
• large lower jaw, nose and tongue
• spacing between the lower teeth
• loss of peripheral vision (compression of the optic chiasm)

Question 11

what are the main clinical signs of agromegaly?

Answer 11

• 1 in 3 have hypertension
• 1 in 10 are hypercalcaemic (high Ca2+)
• 1 in 4 are glucose intolerant
• altered bone structure
• 1 in 5 have hyperthyroidism

Question 12

what is an OGTT test?

Answer 12

an oral glucose tolerance test

Question 13

what does an OGTT test involve?

Answer 13

• glucose is administered and insulin release is stimulated
• hyperglycemia SHOULD (as a result of glucose administeration) supresses GH secretion

Question 14

in the case of an individual with suspected agromegaly, what will happen in the OGTT test?

Answer 14

• hyperglyceamia should suppress GH secretion, however if there is no supression or if GH levels continue to rise - this indicates agromegaly

Question 15

what is an insulin tolerance test & what can it be used to diagnose?

Answer 15

• test that measures the response of the pituitary, adrenal, and insulin receptors to a hypoglycemic episode induced by insulin injection
• it can be used to diagnose diabetes, neuroendocrine tumours, and insulin resistance

Question 16

what effect does hypoglycemia normally have on GH secretion?

hypoglycemia - low glucose levels

Answer 16

• normally stimulates the release of GH and GH levels should then return to normal as blood glucose levels recover their normal level

Question 17

what might be suspected if the baseline GH levels are elevated during an insulin tolerabce test?

Answer 17

• ie if the baseline GH levels are elevated - atypical response
• GH continues to increase even when blood glucose levels are normalised - this isnt normal

Question 18

what is octreotide?

Answer 18

a somatostatin analogue - which will inhibit GH secretion

Question 19

what is the most common symptoms of sheehans syndrome?

Answer 19

• absence of lactation - agalactorrhea
• loss of pituitary gland hormone production - hot flushes, decreased sex drive
• symptoms of hypothyroidism - low T3 and T4 and low TSH - fatigue, bradycardia, hypotension
• adrenal insufficney may also occur - fatigue and weight loss

Question 20

what can occur and is a rare manifestation of sheehans syndrome?

Answer 20

diabetes insipidus

Question 21

in a blood test of a patient suspected with sheehans syndrome, what is to be expected with the levels of anterior pituitary hormones?

Answer 21

there will be a low basal hormone level

Question 22

what is the treatment for sheehans syndrome?

Answer 22

• life long replacement of deficient hormones
• hypothyroidims treted with levothryoxine
• cortisol deficiency treated with prednisone or hydrocortisone
• gonadotropin deficiency can be treated with estrogen and progesterone