Endocrine Abstracts

A 53-year-old Lithuanian man presented with worsening right sided vision (hand movements) and recurrent headaches on a background of previous haemorrhagic strokes. A CT head/angiogram revealed a hyperdense suprasellar mass. His local endocrinology team reviewed and started emergency treatment for presumed pituitary apoplexy (hydrocortisone 50 mg IM/IV 6 hourly) and he was blue-lighted to a tertiary centre for neurosurgical input.

Investigations: Blood tests revealed a hypotonic hyponatraemia (Na 124 mmol/l, Serum Osm 251 mmol/kg, urine Osm 643 mmol/kg, Urine Na 62 mmol/l), normocytic anaemia (Hb 110 g/l Hct 0.3 MCV 84 fL) and an elevated CRP of 21 mg/l. His pituitary profile revealed panhypopituitarism with cortisol 27 nmol/l, ACTH <3 ng/l, Free T4 12.6 pmol/l, TSH 0.08 mU/l, Prolactin 630 mU/l, IGF1 41 mg/l, LH <1 unit/l, FSH <1 unit/l, testosterone <0.5 unit/l. An MRI scan showed a large heterogenous enhancing suprasellar lesion with involvement of the hypothalamus and optic pathways with a wide differential.

Progress and Treatment: Upon transfer, staff noted a polyuria of >450 ml/h with a rise in sodium from to 137 mmol/l. 5% glucose was started intravenously to match urine output. A urine osmolality of 187 mmol/kg revealed a diagnosis of AVP insufficiency which had been unmasked after steroid replacement. 0.5-1 mg s/c DDAVP was started to maintain normonatraemia with repeated dosing once the urine output rose to >200 ml/hr for 2 subsequent hours. A CTCAP, lumbar puncture and ophthalmology review occurred prior to transsphenoidal surgery to relieve pressure on the optic apparatus. A frozen section mid-operation aided diagnostically to facilitate maximal debulking. The histology showed evidence of pus and solid epithelial tumour in keeping with an infected craniopharyngioma.

Conclusions: The patient made a good recovery and was able to read letters with both eyes. Hydrocortisone was weaned to replacement doses (10/5/5 mg), and other hormone replacement initiated (levothyroxine 100 mg OD, 100 mg oral DDAVP at night, testogel 2 pumps daily). Interestingly, blood tests as far back as 2021 show evidence of a normocytic anaemia and low haematocrit, suggesting possible developing hypogonadism even at this stage. It is important to be vigilant for the unmasking of cranial DI post-steroid replacement - the addition of high dose glucocorticoid causes a reduction in CRH mediated AVP production which is usually tonically inhibited by cortisol. Thankfully, this patient’s thirst mechanism was intact to facilitate normonatraemia but a subsequent weight gain at follow-up has revealed possible hypothalamic dysregulation of appetite. This will be assessed further with repeat imaging following a course of external beam radiotherapy to treat residual disease.