Salivary urea, uric acid, creatinin levels and stress axes in chronic renal patients

Aim: CKD is a progressive, irreversible disease that is common in older ages and has a high mortality rate. In this disease, which is characterized by loss of kidney function, uremic metabolites such as urea, uric acid and creatinine accumulate in the blood. There is not enough information about the reflection level of these metabolites in body fluids such as saliva. In addition, the effects of these toxic metabolites on the ANS and HPA axis, two important stress axes of the body, are not well known. The aim of the current thesis is to reveal the level of reflection of these metabolites (urea, uric acid, creatinine) accumulated in the blood in CKD into saliva and the degree to which they affect the stress axes (ANS and HPA). Material and Method: Chronic kidney patients (n=35) who were admitted to the hospital with monthly follow-ups and healthy individuals (n=35) were included in the thesis study. Blood and saliva samples were taken from the participants in the morning (09:00-12:00 h) and their urea, uric acid and creatinine levels were measured. Salivary cortisol measurements were made to determine HPA activity. To determine ANS activity, HRV parameters were calculated by making 5-minute ECG recordings. Results: Blood urea, uric acid, creatinine levels and salivary urea and uric acid levels were found to be high in CKD (p<0.05). Blood and saliva urea levels (r = 0.370) and uric acid levels (r = 414) were positively correlated (p<0.05). In CKD, salivary cortisol level was high (p<0.05) and HRV was low (p<0.05). Conclusion: In CKD, uremic metabolites were all increased in blood but only urea and uric acid were increased in saliva. This finding shows that saliva can be used as a non-invasive medium to detect uremia in CKD. Additionally, the increase in cortisol and decrease in HRV in CKD indicate that stress is high in these patients. However, it has been evaluated that this stressful situation may be related to increased psychological burden rather than uremia. Keywords: ANS, CKD, Cortisol, Creatinine, HPA, HRV, Stress, Urea, Uric Acid