Hypopituitarism and Non-Functioning Pituitary Adenomas
Hypopituitarism and
Non-Functioning Pituitary Adenomas
Non-functioning pituitary adenomas
Non-functioning pituitary adenomas (NFPAs) are bioc cally inert
tumours. They usually present with the physical effects of a pituitary mass
lesion (e.g. visual field loss, headache and hypopituitarism) or, increasingly,
when discovered incidentally on routine brain MRI (‘pituitary incidentalomas’).
Surgical decompression is indicated if there is a visual field defect or if the
lesion is close to the optic chiasm.
The usual route for removal is trans-sphenoidally, although
trans-cranial surgery is occasionally needed. NFPAs can cause hypopituitarism
by compressing the normal gland, which requires endocrine replacement.
Histologically, NFPAs can have positive immunostaining for inactive LH and FSH,
but they do not secret bioactive hormones. Patients with significant
postoperative residual tumour may require radiotherapy.
Hypopituitarism
Causes
Hypopituitarism has several causes, either congenital (from
pituitary transcription factor defects) or acquired. Acquired hypopituitarism
is most commonly caused by the presence of a pituitary tumour. Other acquired
causes include inflammatory and infiltratitive disorders, traumatic brain
injury and radiotherapy (Figure 5.1). In patients with hypopituitarism and a
large empty pituitary fossa on MRI, it is important to enquire about a previous
history of severe headache, as this may reflect missed pituitary apoplexy
(Chapter 36).
