Endocrine Abstracts

A 16-year-old female was referred on a routine basis to endocrinology with short stature and primary amenorrhoea. Meanwhile, she presented acutely via ophthalmology with a bitemporal hemianopia. Urgent pituitary MRI imaging showed a 4.5 x 3.8 x 4.5 cm partially cystic suprasellar mass with optic chiasm compression. Initial biochemistry showed hypogonadotrophic hypogonadism (oestradiol 62 pmol/l, LH 1.7 U/l, FSH 4.5 U/l), a borderline low IGF 1 89 ug/l but otherwise intact pituitary function. Urgent trans-sphenoidal debulking surgery was subsequently performed to preserve visual function. Pathology confirmed an adamantinomatous type WHO grade 1 craniopharyngioma. Post-operative recovery was complicated by panhypopituitarism and polyuria. Polyuria was evident day 2 post-operatively and initially treated with IV Desmopressin as sodium began to rise to 148 mmol/l. Biochemistry confirmed a rising serum osmolality (306 mOsm/kg) with inappropriately dilute urine (urine osmolality 70 mOsm/kg). AVP-deficiency (AVP-D) was diagnosed on day 3 due to persistent polyuria and hypernatraemia and regular Desmopressin was commenced. Subsequent post-operative recovery has proven to be challenging, with AVP-D complicated by hyperphagia, cognitive dysfunction and added instability associated with recurrent antibiotic-resistant E. coli urinary infections. Fluid balance remains a concern as by 6 weeks post-op the thirst reflex remained absent confirming the diagnosis of adipsic AVP-D. Regular oral Desmopressin was commenced aiming to control polyuria however oral intake has remained very poor requiring ongoing critical care nursing to ensure sufficient oversight of fluid balance. Despite regular Desmopressin with close biochemical monitoring, fluid balance and weights, the Sodium concentration has fluctuated, with extremes of Na+ 113 mmol/l and Na+ 164 mmol/l in the six weeks post-operatively. Urine output was still up to 3 litre daily on oral Demsopressin 200 micrograms three times daily but was subsequently curtailed by increased oral Desmopressin dosing. However, this was later complicated by the development of hyponatraemia. A management plan utilising the daily fluid balance and weight to estimate the required oral fluid intake has achieved relative stability but challenges remain in terms of attaining sufficient stability to facilitate a safe future discharge from hospital. Adipsic AVP-D presents as a combination of anti-diuretic hormone deficiency and an absent thirst reflex due to hypothalamic osmoreceptor damage, leading to an extremely problematic disorder of water and sodium balance. It presents a significant challenge in the post-operative period and beyond, particularly when complicated by cognitive dysfunction.