Central diabetes insipidus epidemiology
The incidence of CDI in children presenting with polydipsia and polyuria is low. Factors associated with higher likelihood of pathology include older age, propensity for cold beverage intake, and higher baseline serum Na and osmolality on a WDT 1).
Central DI is observed in 16-34% of patients recovering from sellar region operations and is generally transient; however, this condition may increase the length of hospitalization, as well as cause morbidity after pituitary surgery. In addition, DI can lead to severe hypernatremia if the fluid is not instantly replenished. Hence, monitoring for DI is essential during the first post-operative days; correspondingly, accurate diagnosis followed by correct treatment is crucial 2).
Adult patients with sellar lesion/parasellar lesions
Angelousi et al. systematically reviewed the existing data for defining the prevalence of DI before any treatment in adult patients with sellar lesion/parasellar lesions, excluding pituitary adenomas and pituitary metastases. In total, 646 patients with sellar lesion/parasellar lesions presenting with DI at diagnosis were identified. The most common pathologies of sellar/parasellar lesions presenting with DI at diagnosis were lymphocytic hypophysitis (26.5%), craniopharyngiomas (23.4%), Langerhans cell histiocytosis (18.9%) and Rathke’s cleft cyst (12.7%), accounting for the vast majority (more than 80%) of these lesions. Overall, DI at diagnosis was found in 23.4% of all patients with sellar/parasellar lesions, albeit with a wide range from 10.6% to 76.7%, depending on the nature of the pathology. The highest prevalence of DI was found in less commonly encountered lesions namely germ cell tumors (76.7%), abscesses (55.4%), and neurosarcoidosis (54.5%), each accounting for less than 3% of all sellar/parasellar lesions. Most DI cases (68.8%) were associated with anterior pituitary hormonal deficiencies, in contrast to pituitary adenomas that rarely present with DI. The enlargement and enhancement of the pituitary stalk were the most common findings on magnetic resonance imaging besides the loss of the high signal of the posterior pituitary on T1-weighted images. Resolution of DI spontaneously or following systemic and surgical management occurred in 22.4% of cases. Post-operative DI, not evident before surgery, was found in 27.8% of non-adenomatous sellar/parasellar lesions and was transient in 11.6% of them. Besides distinctive imaging features and symptoms, early recognition of DI in such lesions is important because it directs the diagnosis towards a non-adenomatous sellar/parasellar tumor and the early initiation of appropriate treatment 3).