Dipsogenic Form of Primary Polydipsia in a Young Man and an Emerging Treatment Modality

Abstract

Dipsogenic primary polydipsia is a subset of primary polydipsia characterised by disordered thirst in which the osmotic threshold for thirst is below the threshold for Arginine Vasopressin (AVP) release in patients without underlying psychiatric illness. We report a case of a 19-year-old male undergraduate referred on account of 16 years history of polydipsia and polyuria, with no history suggestive of psychiatric illness. General physical and systemic examinations revealed no abnormality. He was otherwise healthy. He has been normonatremic and polyuric, with low urine osmolality. The result of his water deprivation test showed intact urinary concentrating ability, low-normal serum osmolality and effective diluting capacity, which was consistent with the diagnosis of dipsogenic primary polydipsia. For symptomatic control, a low dose of intermittent desmopressin was given, the frequency of which was tapered down to usage as at when needed and strict water restriction was followed during drug dosing. Making a clear distinction between dipsogenic primary polydipsia and partial central diabetes insipidus, it is required to guide effective therapeutic approach because of the fear of hyponatremia that could arise as a result of ingestion of excessive amount of fluid which can become more pronounced if the patient is on treatment with desmopressin.