Is Everything All Right Behind the Normal Data? A 4-Month-Old Infant With X-Linked Nephrogenic Diabetes Insipidus and his Family-A Case Report

10.6501/CJM.202203_20(1).0003

Wei-Ju Hong；Shih-Hua Lin；Shao-Yen Wu

AVPR 2 ； hypernatremia ； nephrogenic diabetes insipidus ； X-linked

The Changhua Journal of Medicine

20卷1期（2022 / 03 / 01）

20 - 25

英文

Congenital nephrogenic diabetes insipidus (NDI) is a rare renal disorder caused by gene mutations in arginine vasopressin receptor 2 (AVPR2) or aquaporin 2. Clinical signs include polydipsia, polyuria, regular vomiting, and developmental delay in children. This paper reports the case of a 4-month-old male infant presenting with chronic vomiting and a 2-month delay in motor milestones. Laboratory examinations revealed hypernatremia accompanied by an elevated serum osmolality and a very low urine osmolality; the latter did not respond to desmopressin acetate treatment. The plasma sodium level normalized after amiloride and hydrochlorothiazide treatment. Furthermore, sequencing analysis revealed NDI with an X-linked AVPR2 gene mutation. Male patients with NDI caused by AVPR2 mutations display more severe symptoms than female patients; this is due to the X-linked gene being hemizygous. Additionally, some female patients with NDI manifest minor symptoms, and their laboratory data are ＂normal.＂ Those patients are usually underdiagnosed without detailed interpretations of their conditions.