A patient presents with tiredness, dizziness,
headache, visual disturbance, impotence and decreased facial hair. On
examination he has a blood pressure of 110/70 lying 80/ 60 standing. On
examination of his visual fields he is found to have a bitemporal hemianopia.
In this patient the prolactin level is 4000 mIU/L. An insulin tolerance test
is performed and the blood glucose levels falls to 1.2 mmol/L and the patient
becomes sweaty and tachycardic. Blood taken at this time would show:
Absent cortisol response
Exaggerated cortisol response
Increased thyroxine release
Attenuated thyroxine release
Exaggerated growth hormone release
The combination of headache, bitemporal hemianopia and
the prolactin level of > 3,600 mIU/L suggests the patient has a
macroadenoma. Chromophobe adenoma and acidophil adenoma can produce prolactin.
This patient is likely to have an impaired response to the insulin
tolerance test as prolactinoma may cause hyposecrestion of other hormones.
It is likely that this patient has corticotrophin deficiency as he has
features that are suggestive of this (tiredness, dizziness, low blood pressure
with postural drop)
Last Updated: 08/07/04