Pituitary

Question 1

What hormones does the anterior pituitary secrete? Under what influence?

Answer 1

Growth hormone
- Growth hormone releasing hormone

Adrenocorticotrophic hormone
- Corticotrophin releasing hormone

Luteinising hormone and Follicular stimulating hormone
- Gonadotrophin releasing hormone

Prolactin

• Dopamine
• Thyrotropin releasing hormone

Thyroid stimulating hormone
- Thyrotropin releasing hormone

Question 2

What is the combined pituitary function test? What are the contraindications? What are the side effects?

Answer 2

An assessment of the pituitary across all the hormones it releases. Insulin, TRH and GnRH are given, with levels of pituitary hormones measured at 0 minutes, and again every half an hour:

• GH, blood glucose and cortisol: up to 120 minutes
• LH/FSH, TSH, Prolactin: up to 60 minutes

It is contraindicated in ischaemic heart disease, untreated hypothyroidism and epilepsy.

Side effects of the insulin given are sweating, palpitations and loss of consciousness; nausea and vomiting result from the TRH and GnRH

Question 3

What are the normal results of the combined pituitary function test?

Answer 3

GH: rises to above 10
Blood glucose: needs to go below 2.2 for the test to work, should rise back to normal by 120 minutes
Cortisol: peaks at 30/60 minutes, and should go above 550
LH: should rise above 10
FH: should rise above 2
Prolactin: should gradually rise but stay below 3000

Question 4

What does a prolactin of above 6000 suggest?

Answer 4

Prolactinoma; no other disease can raise the prolactin so high

Question 5

What can cause panhypopituitarism?

Answer 5

The most common cause is a non-secreting pituitary adenoma, which presses on the pituitary to reduce the hormone secretion. Adenomas can also secrete any combination of the hormones.

Question 6

What is the classification of pituitary adenomas?

Answer 6

• Microadenomas <10mm

- Macroadenomas >10mm

Question 7

What is the side effect of a large pituitary adenoma?

Answer 7

Optic chiasm compression, leading to bitemporal hemianopia

Question 8

What is the treatment for a prolactinoma?

Answer 8

Cabergoline; this should shrink the adenoma, removing the need for surgery

Question 9

What is the treatment for acromegaly?

Answer 9

1) Surgery
2) Radiation
3) Cabergoline
4) Octreotide

Question 10

What is the test for acromegaly?

Answer 10

Glucose tolerance test

IGF 1

Question 11

What hormone replacement should be given to someone who has hypopituitarism?

Answer 11

• Hydrocortisone
• Thyroxine
• Oestrogen
• Growth hormone

Hydrocortisone is the most urgent

Question 12

What does the posterior pituitary secrete?

Answer 12

• ADH

- Oxytocin

Question 13

What are the causes of excess ADH?

Answer 13

Lungs: small cell cancers, pneumonia
Brain: injury, meningism, tumours
Iatrogenic: SSRIs, PPIs

Question 14

What does excess ADH cause?

Answer 14

SIADH: euvolaemic hyponatraemia

Question 15

What can cause ADH deficiency?

Answer 15

Diabetes insipidus:

• Cranial: failure of production
• Nephrogenic: failure of sensitivity