Hyponatraemia after orthopaedic surgery – a case of pituitary apoplexy

Abstract

Case reportFour days after an elective total hip replacement, a previously fit and healthy 70-year-old man complained of a headache before collapsing on the ward with a Glasgow Coma Score of 5. His blood pressure was recorded at 80/45 and his temperature was 38ºC. No fit was witnessed; although his conscious level improved, he remained confused with slurred speech. His new patient finger prick capillary glucose was 4.7. A right-sided sixth cranial nerve palsy was noted causing paralysis of the lateral rectus with diplopia. His blood sodium concentration was recorded as 117 mmol/l. Treatment was instigated immediately with fluid restriction to 750 ml per 24 h and appropriate biochemical investigations were requested. A short synacthen test revealed a baseline serum cortisol level of 160 nmol/l at 09:30 (normal morning range, 450-700 nmol/l), rising to 461 nmol/l 60 min after administration of 250 µM tetracosactrin. Random serum sodium osmolality was recorded as 245 mOsmol/kg (normal range, 275-295 mOsmol/kg) and urine osmolality was 417 mOsmol/kg. A chest radiograph and ECG were requested and antibiotics were commenced for basal pneumonia. Hydrocorticone (100 mg i.v.) was administered. Serum prolactin, follicle stimulating hormone (FSH), luteinising hormone (LH), testosterone, thyroid stimulating hormone (TSH), T3 and T4 levels were checked and urgent imaging of the pituitary fossa was arranged. A computed tomography scan revealed an enlargement of the sella turcica with a low density mass arising from the pituitary fossa into the supraseller cistern extending a little to the left of the mid-line with lateral extension into the cavernous sinus. The mass abutted both internal carotid vessels and the optic chiasm was significantly elevated and displaced. Appearances were suggestive of a pituitary macro-adenoma.Hormone assays revealed a low FSH level at 1.5 mIU/l (normal range, 1.5-12.5 mIU/l); a low LH level at 1.6 mIU/l (normal range, 1.7-8.4 mIU/l); low TSH at 0.12 (normally, 0.3-4.5); low free T4 level 9.7 pmol/l (11-24 pmol/l); low prolactin at 25 mIU/l (normal range, 98-450 We describe a case of profound hyponatraemia in a postoperative patient after total hip replacement caused by corticosteroid insufficiency due to a non-functioning pituitary macroadenoma diagnosed by dynamic endocrine tests and radiological imaging. Adopting a multidisciplinary approach, successful diagnosis and management lead to a complete recovery without any long-term sequelae.

Pituitary apoplexy presenting with anorexia and hyponatraemia

“…Precipitating factors have been identified in up to 40% of cases of pituitary apoplexy 2. Previous reports of atypical cases have identified several precipitating factors such as orthopaedic operation,7 9 cardiac operation8 and pregnancy 6. Long-standing hypertension, the most common (26%) predisposing factor,2 seemed to be a precipitating factor in our case.…”

Pituitary apoplexy following shoulder arthroplasty: a case report

“…These signs prompted radiological imaging and a definite diagnosis. Pituitary apoplexy presenting as hyponatremia secondary to hormone deficient adrenal insufficiency, following orthopedic surgery is documented, [ 2 ] but requires a high index of suspicion for investigations to be directed towards an early diagnosis.…”

Central Hypothyroidism in Severe Sepsis

“…Thus, we consider the orthopedic surgery as the primary event, being a procedure a priori known to be accompanied by a large blood loss that could lead to ischemia by hypoperfusion, and/or association of other factors, as intraoperative or postoperative hypotension related to anesthesia, anticoagulation and/or fat/air/ bone marrow microemboli (3,(5)(6)(7).…”

“…There are patients that present only ischemic infarction without hemorrhage, while others only primary hemorrhage. The general consensus is that the pituitary apoplexy after surgery is caused by a multitude of factors that include perioperative hypotension related to anesthesia or hypovolemia, anticoagulation, and microemboli (fat, air, bone marrow or cement) (5)(6)(7)(8).…”