In most healthy adults and children, the posterior pituitary emits a hyperintense signal visible in T1-weighted midsagittal images. This “bright spot” is almost always present in patients with primary polydipsia but is always absent or abnormally small in patients with pituitary DI,沒有亮點要考慮是central DI
病患在限水後尿液的滲透壓回到正常值,因此為primary polydipsia
在給予DDAVP後,病人尿液的滲透壓仍然偏低,因此應為病患對於AVP反應不佳,此為nephrogenic DI