Taste changes and saliva composition in chronic kidney disease

Objective: To determine whether there is an association between changes in salivary composition and altered taste perception in chronic kidney disease (CKD) patients. Design: Cross-section observational study. Setting: Tertiary hospital renal outpatient clinic. Subjects: Thirty CKD patients (24 males, six females, age 69.7 ± 14.2 years), with glomerular filtration rate (GFR) <25 mL/ min and five controls, (one male, four females, age 44.6 ± 10.3 years) with GFR>80 mL/min. Intervention: Participants performed a taste identification task to assess perception of the five primary tastes: sweet, salty, bitter, sour and umami. Perceived intensity was rated on a 100 mm visual analogue scale to determine sensitivity, and liking was rated using a nine-point hedonic scale. A saliva sample was collected to determine biochemical composition. Main outcome measure: Recognition, perceived intensity and liking of the five primary tastes. Results: It was observed that CKD patients have increased salivary bicarbonate, potassium and urea concentrations (p<0.05) and a poorer ability to perceive sour, umami and bitter tastes (p<0.05) when compared to controls. Bicarbonate concentration in saliva was inversely related to both liking and intensity of umami taste and to the intensity of sour taste (p<0.05), whilst salivary urea was linked to the perceived intensity of bitter taste (p<0.05)