Endocrine Abstracts

Background: The blood supply of the pituitary gland comes via a portal circulation from the hypothalamus. During pregnancy, the anterior pituitary gland enlarges but the blood supply cannot increase, as it is derived from a capillary plexus. The pituitary is thus vulnerable to arterial pressure changes and infarction secondary to hypotension. We describe a case of a male patient with large pituitary adenoma who developed Sheehan’s like syndrome due to adenoma infarction secondary to postoperative hypotension, confirming that the mechanism of Sheehan’s syndrome is a combination of critical pituitary ischaemia because of its unique blood supply, and relatively mild hypotension, which is not otherwise life threatening.

Case: An 84 year-old male was found to have bilateral hemianopia. Subsequent MRI imaging confirmed a large (non-functioning) pituitary macroadenoma associated with chiasmal compression and hormonal evidence of partial hypopituitarism. The patient was offered a TSS, but he chose a conservative approach. A follow up pituitary MRI showed an increase in the height of the lesion with increase in chiasmal compression and surgery was again offered to the patient. He agreed to be done after another major shoulder surgery (in another institution), which was a priority for him. In the immediate postoperative period (orthopedic surgery), he vomited 25 times with hypotension and severe visual restriction and required intensive support to maintain his blood pressure. Weeks later, he noticed dramatic improvement in his vision. Post surgery, the prolactin level dropped from peak level of 1095 to 48 milliunit/L (60–300), suggesting lactotroph infarction. Repeated pituitary MRI showed dramatic reduction in the height of the pituitary macroadenoma due to an infarction. This correlated with the improvement in VF.

Conclusion: The pituitary is vulnerable to infarction either in the presence of a tumour or at the end of pregnancy, both times of pituitary enlargement.