Endocrine Abstracts

Lithium-induced Nephrogenic Diabetes Insipidus is the commonest type of Nephrogenic Diabetes Insipidus. Management remains challenging even when Lithium is discontinued as non-reversibility of Diabetes Insipidus can be irreversible. Possible treatment options include Hydrochlorothiazide, Amiloride or Acetazolamide. We report a case of possible Nephrogenic Diabetes Insipidus 1 year after discontinuation of Lithium. Our patient is an 85-year old lady who was referred for an Endocrinology opinion as she was noted to have polydipsia and polyuria on the ward. It was noted that prior to this admission with a fall, she had been on Lithium therapy for 20 years and this was stopped 1 year previously due to declining renal function. On admission, she had an acute on chronic kidney injury with urea 26.9 and creatinine 349. Baseline creatinine was around 240. Her fluid balance was on average negative 1,900 ml in a day and she passed more than 3 l of urine per day. A random serum osmolality was 317 mosm/kg with urine sodium 53 mmol/l and urine osmolality 265 mosm/kg. Following an overnight water deprivation period, her morning plasma sodium was 143 mmol/l, serum osmolality was 322 mOsm/kg and urine sodium was 48 mmol/l and urine osmolality was 290 mOsm/kg. She also passed 1,800 ml of urine over those hours. She has been booked for a formal water deprivation test as an outpatient.