Idiopathic central diabetes insipidus (CDI) is defined in CDI patients without definite etiology. Some patients initially diagnosed as idiopathic CDI progressed to organic causes. We reviewed clinical, endocrinological, and radiological courses of 20 patients who was initially diagnosed as idiopathic CDI, to assess the predicting factors for progression to brain tumors.

We reviewed the medical data and followed up their clinical courses in 20 CDI patients who had no definite organic etiology, such as malformation, tumor, at the time of diagnosis.

Our study included 15 males and 5 females. Mean age of CDI diagnosis was 7.8±3.6 (2.1-14.7) years. Mean follow-up duration was 8.6±5.1 (1.5-18) years. Six (30%) patients were diagnosed as brain tumor during follow-up. Ten (50%) of 20 patients had growth hormone deficiency. Multiple pituitary hormone deficiencies were found more frequently in brain tumor patients than idiopathic patients (60% vs 7%, P =0.037). Pituitary stalk thickening (PST) and loss of posterior pituitary signal were observed in 9 patients (47%), respectively. The newly development of PST was observed in patients diagnosed as brain tumor.

About 30% of idiopathic CDI patients progress to organic disease such as germ cell tumor or histiocytosis. If there are multiple anterior pituitary hormone deficiency or newly development of PST, more close and careful follow-up is needed.