ESPE Abstracts

Introduction: Primary polydipsia is rare during adolescence and is known to be associated with psychiatric disorders or psychological stress. Differential diagnosis includes endocrine, neurologic, renal, and iatrogenic causes.

Case Report: A 14-year-old male presented with polydipsia and polyuria that persisted for 6 years. His fluid intake was about 9 liters a day and he woke up for voiding once or two times every night. He had no fever, headache, abdominal pain, weight loss, vomiting, or any other neurological deficit. His past medical history was unremarkable. Also, there was no family history related to endocrine, renal, or psychiatric diseases. His physical and intellectual development was normal. On physical examination, his height was -0.47 standard deviation score (SDS), weight -0.73 SDS, and body mass index -0.72 SDS. Neurologic examination revealed no abnormality. Laboratory data showed normal concentrations of serum sodium, potassium, creatinine, and glucose. Serum and urine osmolality was 281 and 91 mOsm/kg, respectively. Hormonal studies revealed normal thyroid-stimulating hormone, thyroxine, cortisol, and adrenocorticotropic hormone. A 12-hour water deprivation test showed an increase in urine osmolality up to 778 mOsm/kg, with no changes in serum sodium, osmolality, and antidiuretic hormone. He was diagnosed with primary polydipsia and recommended to restrict fluid intake. His polydipsia and polyuria disappeared completely within 2 weeks after fluid restriction.

Conclusion: This case report suggests that primary polydipsia might be observed in adolescents without psychological risk factors. Sufficient awareness of clinical features and biochemical characteristics including a water deprivation test is important to identify this disorder.