POLYDIPSIA AMONGST ADULTS WITH A LEARNING-DISABILITY IN AN INSTITUTION

A hospital-based adult learning disabled population (n=371) was screen ed for polydipsia with the help of a purpose-designed questionnaire. P olydipsia was defined as excessive drinking of more than 31 of non-alc oholic fluid over a 24-h period. Altogether, 23 (6.2%) subjects were f ound to have polydipsia. The polydipsic group was compared with the wh ole hospital population on variables such as age and IQ distribution. A matched group of 23 individuals without a history of polydipsia was drawn from the same hospital population. The polydipsic and the matche d group were compared using various biochemical and psychological meas ures. Thirty-five per cent of polydipsic patients, compared to 13% of the matched group, showed evidence of compensated hyponatraemia. This difference was not significant. There was no significant difference be tween die polydipsic and the matched group in the frequency of psychia tric illness, behavioural problems or autism. There also was no signif icant difference in the IQ levels of the polydipsic patients and the t otal hospital population. Polydipsia in this population is largely see n as part of an abnormal behavioural repertoire without any evidence o f possible organic cause, except unidentified diabetes mellitus. Klein Levin syndrome and pica were represented in the polydipsic group, but not amongst the matched group.