Introduction: Psychogenic polydipsia is a relatively uncommon condition characterized by overconsumption of water. It is known to be prevalent amongst psychiatric patients, but less common in the general population.
Case report: A previously well 18-month-old girl presented to the emergency department in status epilepticus. There was no history of fever, recent weight loss, infection, trauma or any systemic medications. Post event questioning established a history of bottle water feeding in excess of 3 litres a day, with a history of nocturia (heavy nappies during the night). Safeguarding concerns were excluded. Neurological examination was unremarkable post seizure and there were no other significant signs seen on systemic examination. CT scan of the head showed no significant abnormality excluding an intracerebral pathology.
Haematology and biochemistry: The seizure was controlled with routine clinical care (buccal midazolam and IV lorazepam). We treated the hyponatraemia with 20 ml/kg Nacl bolus and 2 ml/kg of 3% hypertonic saline. The seizure terminated following this and the hyponatremia slowly resolved over next 68 h. Meanwhile, the patient was maintained on intravenous fluids and subsequently graded on to oral fluids. Overnight water deprivation revealed that the urine osmolality improved to 477 mosmol/kg with a serum osmolality of 293 mmol/kg (Table 1).
|Serum osmolality||276 mmol/kg|
|Serum Cortisol||286 nmol/l|
|White Cell Count||13.4|
|Urine Osmolality||107 mOsmol/kg|
|Urine sodium||24 mmol/l|
Conclusion: Diagnosis of pathological polydipsia and polyuria is difficult to recognise in a toddler in nappies. It can be often be missed and misdiagnosed as UTI. Seizure in this context is extremely rare but prompt recognition of the biochemical changes consistent with Diabetes insipidus or psychogenic polydipsia requires urgent intervention and investigation for the correct diagnosis and outcome. This case is even more unusual in that it occurred in as far as we know a normal child without any co-morbidity.
22 - 24 Nov 2017
British Society for Paediatric Endocrinology and Diabetes