Thirst perception and arginine vasopressin production in a kindred with an activating mutation of the type 2 vasopressin receptor: the pathophysiology of nephrogenic syndrome of inappropriate antidiuresis.
BACKGROUND
Activating mutations of the vasopressin receptor gene on the X chromosome cause the nephrogenic syndrome of inappropriate antidiuresis (NSIAD). We describe a male child who presented with persistent hyponatraemia and whose mother was also found to be hyponatraemic. She had learnt to avoid excess fluid consumption because of associated malaise. Both individuals had a subnormal ability to excrete a water load with mother also demonstrating a heightened sense of thirst at low serum osmolalities.


RESULTS
Mother and child were found to have the previously characterised activating mutation (p.Arg137Cys) of the arginine vasopressin receptor type 2 gene (AVPR2), but had measurable levels of AVP when hyponatraemic.


CONCLUSIONS
We conclude that female carriers of activating mutations of the vasopressin receptor are susceptible to hyponatraemia and therefore need to be provided with advice regarding fluid intake. An altered thirst perception may increase susceptibility to hyponatraemia. We confirm that the presence of measurable amounts of AVP in patients with hyponatraemia does not exclude the diagnosis of NSIAD.
Gupta
S
S
Department of Paediatrics, Royal Victoria Infirmary, Newcastle upon Tyne Hospitals NHS Trust, Newcastle upon Tyne, NE1 4LP, UK.
Cheetham
T D
TD
Lambert
H J
HJ
Roberts
C
C
Bourn
D
D
Coulthard
M G
MG
Ball
S G
SG
D000328:Adult; D001127:Arginine Vasopressin / Q000378:metabolism*; D005260:Female; D020022:Genetic Predisposition to Disease; D006801:Humans; D007010:Hyponatremia / Q000235:genetics; D007177:Inappropriate ADH Syndrome / Q000235:genetics*; D007223:Infant; D008297:Male; D009154:Mutation / Q000502:physiology; D010465:Perception / Q000502:physiology*; D017483:Receptors, Vasopressin / Q000235:genetics*; D013894:Thirst / Q000502:physiology
D017483:Receptors, Vasopressin; D001127:Arginine Vasopressin