Endocrine Abstracts

Arginine vasopressin resistance (AVP-R) (previously termed nephrogenic diabetes insipidus) is well known to be associated with lithium treatment. However, cases are usually mild and patients can almost always compensate for their polyuria with excessive fluid intake. We present the case of a moribund patient who required intensive care admission secondary to AVP-R, developing hypernatraemia to 183mmol/l and serum osmolality of 394mmol/kg. A 68 year old gentleman, on lithium treatment for bipolar disorder, presented with an acute kidney injury and lithium toxicity. At this point he was compos mentis, and after being treated with intravenous fluids, his renal function and lithium levels improved. However, his sodium level rose, and, in the subsequent days, he significantly deteriorated, suffering from polyuria and polydispia. His GCS dropped as low as 8, and at this point his condition rapidly worsened, developing worsening hypernatraemia with a sodium of 183 and serum osmolality of 394mmol/kg. The diagnosis of lithium induced AVP-R was recognised upon discussion with endocrinology, and his intravenous fluid regime intensified, with rapid administration of 5% dextrose. He was transferred to intensive care immediately, and administered desmopressin intravenously, requiring doses up to 3micrograms. At its greatest, his fluid intake and urine output exceeded 6L over 24 h. His condition gradually improved over the next few days, with careful management of his fluid balance, titration of desmopressin and reduction in serum sodium to normal. His cognitive state returned to baseline and, after a short period of rehabilitation and monitoring, was discharged home on 100micrograms TDS of oral desmopressin with psychiatric follow up for inititation of an alternative mood stabiliser. From a review of the literature, there have been very few documented cases of AVP-R secondary to lithium as severe as this.