Background: In a paediatric setting polydipsia can be a commonly reported symptom which is usually innocent and habitual in nature. Diabetes Insipidus is a rare cause of pathological polydipsia. A high index of suspicion must be used in patients who exhibit other symptoms alongside polydipsia and investigations considered.
Case presentation: We present three patients who have presented to a district general hospital within a short period of time with subsequent diagnoses of Central Diabetes Insipidus (DI). Case A; a 12 year old boy presented with polyuria, polydipsia and poor appetite. Endocrine workup (thyroid function tests, short synacthen test and renal ultrasound) was normal. MRI brain revealed absent posterior pituitary and the patient was diagnosed with isolated cranial DI. Case B; a 10 year old boy with a history of previous basal skull fracture following a road traffic accident, presented to the General Practitioner (GP) with secondary nocturnal enuresis. Medical treatment for nocturnal enuresis (desmopressin) started by the GP showed some initial improvement in symptoms, but when symptoms deteriorated and polydipsia developed he was referred for paediatric assessment. Endocrine workup confirmed partial cranial DI. Case C; an 11 year old boy who presented with polyuria, polydipsia and lethargy, initial endocrine workup showed absent posterior pituitary on MRI brain but was otherwise normal. Repeated testing at regular intervals revealed mildly abnormal thyroid function at 1 year, repeat MRI head was performed showing germ cell tumours requiring treatment with chemotherapy and radiotherapy.
Conclusion: Cranial DI as a cause for polyuria and polydipsia remains a rare cause but continued neuro-endocrine surveillance is essential for potential identification of an underlying cause as demonstrated in our third case.
01 - 03 Oct 2015
European Society for Paediatric Endocrinology