Xerostomia, thirst, sodium gradient and inter-dialytic weight gain in hemodialysis diabetic vs. non-diabetic patients

BACKGROUND: In hemodialysis (HD) patients, xerostomia and hyposalivation may intensify sensations of thirst, and contribute to the intake of fluids and excessive inter-dialytic weight gain (IWG). Since IWG is regarded to be higher in diabetic patients than in non-diabetics HD enhancing their mortality, it is crucial to define plausible underlying causes. Therefore, the study investigates factors contributing to the increased IWG in diabetic HD patients. MATERIAL AND METHODS: The study included 97 HD patients (38 diabetics) receiving hemodialysis. All participants completed surveys comprising the Dialysis Thirst Inventory (DTI) and Xerostomia Inventory. Unstimulated whole saliva flow rate (USWFR) was measured, with USWFR below 0.1 mL/min being regarded as hyposalivation. Additionally, pre- and post-dialysis serum sodium concentration, sodium gradient and IWG were assessed. In diabetic HD patients, hemoglobin A1c (HbA1c) level was measured. RESULTS: Significantly higher scores were found in diabetic than non-diabetic HD patients with regard to DTI (21.2±7.7 vs. 17.1±6.2: Z=2.44, p=0.03) and xerostomia (40.5±6.1 vs. 29.9±14.4: Z=4.15, p=0.003). Hyposalivation was observed more often in diabetic HD patients (Z=2.23, p=0.04). IGW was significantly higher in participants with diabetes (Z=2.44, p=0.03), as was the pre-dialysis sodium serum (Z=3.4, p=0.008). High levels of HbA1c were associated with lower levels of serum sodium (r=-0.67 p<0.05). HbA1c positively correlated with pre-dialysis sodium gradient (r=0.66 p<0.05). However, multiple regression analysis found that the only predictors of increased IWG (>4.8 IWG%) in diabetic patients remained saliva flow rate and pre-dialysis sodium gradient. CONCLUSIONS: Concomitant diabetes in hemodialysis patients appears to intensify subjective xerostomia and thirst sensation. It also leads to excessive IWG by the increase of pre-dialysis serum sodium gradient. Key words:Diabetes mellitus, hemodialysis, hyposalivation, inter-dialytic weight gain, sodium gradient.