Salivary osmolality and hydration status in children with cerebral palsy

Unstimulated whole salivary parameters have been identified as potential markers of hydration status. Reduced salivary flow rate and increased salivary osmolality have been shown to be useful to identify dehydration, even when minimal loss of body water occurs. This study aimed to evaluate whether unstimulated salivary flow rate and salivary osmolality from individuals with cerebral palsy correlate with plasma and urine osmolality.

Thirty-five male and female children, aged 9-13 years old, diagnosed with cerebral palsy were compared to 27 nondisabled children (10-12 years old). Unstimulated whole saliva was collected under slight suction and salivary flow rate (ml/min) was calculated. Plasma without venostasis and urine were also collected. Salivary, plasma and urine osmolality were measured using a freezing point depression osmometer.

Cerebral palsy children presented a reduction in salivary flow rate (50%) compared to the control group (P < 0.01). Moreover, an increase in salivary (50%), plasma (3%), and urine osmolality (20%) was also observed in the cerebral palsy children compared to the control group (P < 0.01). Salivary flow rate was negatively correlated with the salivary, plasma and urine osmolality (P < 0.01). Salivary osmolality correlated positively with plasma and urine osmolality (P < 0.01).

Cerebral palsy children seem to present impaired adequate hydration status. Since the possible hypohydration condition may be reflected in saliva fluid, which could compromise the protective function exerted by saliva, the earlier this condition is identified the greater the chances of administering preventive measures. Moreover, salivary osmolality is a reliable parameter that reflects changes in plasma and urine.