Endocrine Abstracts

Case history: A 76-year-old female presented following an unwitnessed. On arrival she was confused, dehydrated, complaining of nausea, constipation and abdominal pain. Bloods tests revealed serum calcium of 3.6 mmol/l. She had a history of bipolar disorder and had been taken off lithium due to suspected lithium-induced hyperparathyroidism. Whilst an inpatient, she had a sudden drop in consciousness (Glasgow Coma Scale 3). She was hypotensive, dehydrated and had an average urine output of 130 ml/h. She was intubated, ventilated and admitted to the Intensive Care Unit. Serum sodium and calcium were 157 and 3.54 mmol/l, respectively. She remained polyuric and was investigated for diabetes insipidus.

Investigations: Computed tomography (CT) on admission showed age-related atrophy with nil acute changes. Magnetic resonance imaging (MRI) of the head showed moderate chronic small vessel disease and evidence of a small old infarct in the left cerebellar hemisphere, but nil acute findings. A repeat CT head following the acute deterioration did not reveal any new features. A lumbar puncture was performed.

Results and treatment: Cerebrospinal fluid analysis was unremarkable. A collateral history revealed a history of polydipsia and polyuria prior to admission. A diagnosis of lithium-induced nephrogenic diabetes insipidus was made. She was managed with high dose desmopressin, as well as a trial of indometacin and amiloride.

Discussion and conclusion: We present a case of lithium-induced nephrogenic diabetes insipidus. Desmopressin, diuretics and non-steroidal anti-inflammatory drugs have been used to manage nephrogenic diabetes inspidus related to lithium use. Nephrogenic diabetes insipidus has been seen to persist despite discontinuation of lithium. Patients taking lithium should be monitored for signs of electrolyte disturbance. Diabetes insipidus should be considered in patients presenting with polyuria and polydipsia of a background of lithium use.