A patient with partial central diabetes insipidus: Clarifying pathophysiology and designing treatment

Studies were undertaken in a 32-year-old man who developed polyuria (4 L/d) a few days after a basal skull fracture; the condition persisted 1 year af ter the accident, The other major features were thirst, a plasma sodium of 143 mmol/L, 24-hour urine osmolality of 221 mOsm/kg H2O1 and levels of vaso pressin in plasma that were less than 0.5 pg/mL on 20 separate occasions. T he 24-hour urine volume implied that the diagnosis was partial rather than complete central diabetes insipidus; however, several random urine samples had a much higher osmolality, An infusion of hypertonic saline led to the r elease of vasopressin and the excretion of concentrated urine. We propose t hat the basis for the lesion may be the transection of some, but not all, o f the fibers connecting the osmostat and vasopressin release center. This p artial transection could permit vasopressin to be secreted in response to a larger rise in plasma sodium concentration. This pathophysiologic analysis provided the basis for therapy to minimize the degree of polyuria, (C) 200 1 by the National Kidney Foundation, Inc.