ESPE Abstracts

Introduction: Polydipsia and polyuria are one of the common chief complaints in the field of pediatric endocrinology. The differential diagnosis of polydipsia and polyuria are various diseases including diabetes mellitus (DM), central diabetes insipidus (CDI), and primary polydipsia (PP). Although DM is not difficult to diagnose, between DI and PP is sometimes difficult.

Aim: The objective of our study is to reveal the incidence of CDI, and to investigate predictive factors for differentiation between CDI and PP.

Methods: This study was a retrospective chart review, and performed from January 2014 to December 2018 in Department of pediatrics, Kurume University Hospital in Japan. The chief complaints of the patients, whose age was under the age of 15 years, were polydipsia and polyuria.

Results: The number of first time patients was 1611 during this period. The number having the chief complaint of polydipsia and polyuria was 27. Type 1 DM (T1DM) was found in 16 out of the 27 patients, CDI was found in 5 out of 27, PP was found in 5 out of 27, and nocturnal enuresis was found in 1 out of 27. The incidence of T1DM was 2.2 per 100,000 population, CDI was 0.7 per 100,000 population in this study. Age, sex, duration of symptoms, height SD, Na, Hb, Alb, BUN, plasma/urine osmolality, and AVP had no significant differences between CDI and PP. The urine specific gravity was significantly lower in CDI than in PP (1.005±0.002 vs. 1.015±0.004, P=0.004). The amount of drinking and urine volume was significantly higher in CDI than in PP (3618±850 vs. 1900±529 ml/m², P=0.0006, 3707±1278 vs. 13641±881ml/m², P=0.001). Urine osmolality tended to be lower in CDI than in PP (135.5±35 vs. 430.4±306.6 mOsm/kg, P=0.09). MRI was performed in 5 patients of CDI and 4 patients of PP. Posterior pituitary bright spot showed absence in all 5 CDI and 1 PP patients in T1-weighted image. Pituitary gland and stalk of 4 CDI patients showed abnormal findings, such as pituitary gland enlargement and pituitary stalk thickening. Whereas, 3 PP patients showed normal MRI findings.

Conclusions: The incidence of T1DM was 2.2 per 100,000 population, and the incidence of CDI was 0.7 per 100,000 population of children. Our data suggests that the urine specific gravity, the amount of drinking and urine volume, urine osmolality and MRI may be predictive factor for differentiation between CDI and PP.