Recurrent hypertonic dehydration due to selective defect in the osmoregulation of thirst.
A 6-year-old girl with recurrent episodes of hypertonic dehydration was studied. She denied thirst even with a plasma osmolality as high as 421 mosmol/kg. The hypernatremia was associated with an ability to concentrate urine (854 mosmol/kg). Volume expansion with water corrected hypernatremia (162 to 148 mEq/l) and resulted in an increased urine flow and urinary dilution (137 mosmol/kg) because of suppression of endogenous vasopressin (AVP) release (5.1 pg/ml). Hypertonic saline infusion raised the plasma AVP level (25.6 pg/ml) in response to changes in plasma osmolality (305 to 330 mosmol/kg) and led to a maximal urine osmolality of 818 mosmol/kg. With chronic forced fluid intake, the patient maintained a normal serum sodium concentration (range, 135-145 mEq/l) with a urine osmolality as low as 65 mosmol/kg. These findings are consistent with an isolated defect in the osmoregulation of thirst as the cause of the chronic hypertonic dehydration without deficiency in AVP secretion.
Assadi
F K
FK
Department of Pediatrics, University of Illinois Hospital, Chicago 60612.
Johnston
B
B
Dawson
M
M
Sung
B
B
D001127:Arginine Vasopressin / Q000378:metabolism; D001921:Brain / Q000473:pathology; D002648:Child; D003681:Dehydration / Q000209:etiology* / Q000503:physiopathology; D005260:Female; D006801:Humans; D006955:Hypernatremia / Q000503:physiopathology*; D007671:Kidney Concentrating Ability / Q000502:physiology; D008279:Magnetic Resonance Imaging; D013894:Thirst / Q000502:physiology*; D014882:Water-Electrolyte Balance / Q000502:physiology*
D001127:Arginine Vasopressin