Endocrine Abstracts

Pituitary apoplexy caused by pure infarction is rare. Here we present three cases of pituitary macroadenoma infarction following hypotension.

1. An 84 year old gentleman had a 2 × 2 cm pituitary macroadenoma causing chiasmal compression and a bitemporal hemianopia. He had panhypopituitarism and was on prednisolone, thyroxine and testosterone replacement. Before surgical intervention of the macroadenoma, he fell and broke his humerus, which required internal fixation but was complicated by an infected prosthesis. He required further operative interventions. Following a four hours procedure, he reported worsening of vision, which resolved spontaneously. His prolactin which had been 1095 fell to 48 mU/l and a three months interval MRI showed a reduction in size of the pituitary macroadenoma. Pituitary MRI two years later shows only a slender amount of tissue in the sella.

2. A 68-year old man underwent elective coronary artery bypass grafting (CABG). Post operatively he complained ofheadache, blurred vision and had a left sided third nerve palsy. CT head and MRI pituitary confirmed a 3.5 cm pituitary macrodenoma stretching the optic chiasm. Pituitary profile one day following CABG showed TSH 0.89 (NR 0.3–4.2 mU/l), T3 2.7 (2.5–5.7 pmol/l), T4 8.1(NR 9.0–23.0 pmol/l), 3 pm cortisol 125, LH 1.3 (2.0–12.0 u/l), FSH 2.2 (1.7-8.0 u/l), GH 0.17 ng/l, prolactin <13 mU/l. He was started on prednisolone replacement. Because of his recent CABG, timing of neurological surgical intervention was considered carefully. On review in neurosurgery outpatients, a pituitary MRI showed a marked reduction in the size of pituitary adenoma with no compromise of optic chiasm.

3. A 70-year old man with known severe aortic stenosis developed symptoms of a TIA. CT head identified a 1.8 cm pituitary macroadenoma. MRI pituitary showed no chiasmal compromise. Baseline pituitary function showed no deficiency. His cardiac and neurological symptoms with aortic stenosis necessitated urgent valve replacement. He was on cardiopulmonary bypass with BP 60–80 mmHg systolic for one hour during the surgery. He developed secondary hypothyroidism few weeks later. His repeat MRI showed complete involution of the macroadenoma.

Conclusion: Sheehan syndrome is pituitary infarction due to systemic hypotension in physiologically enlarged pituitary. Our patients demonstrate that the same pathophysiology can cause hypopituitarism in males who have a pituitary adenoma rather than pituitary hyperplasia of pregnancy. The location of pituitary gland and its unusual blood supply makes it prone to ischemia in setting of systemic hypotension when physiologically or pathologically enlarged.