unfortunately , large numbers of patients have gone undiagnosed at earlier stages of ckd , which increases the risk for development of end stage renal disease ( esrd ) . patients with ckd demonstrate activation of inflammatory pathways , which is accompanied by increased inflammatory markers like cytokines . the elevated levels of cytokines such as interleukin-6 ( il-6 ) and tumor necrosis factor - alpha ( tnf- ) have been shown in esrd . it has been shown that inflammatory markers such as il-6 and tnf- enhance the risk of cardiovascular mortality . furthermore , it is confirmed that oral diseases including oral cancer , lichen planus , and periodontal diseases are associated with il-6 and tnf- deregulation . according to some previous studies , we can consider the merit of il-6 measurement as a prognostic indicator and provide a clinical perspective on il-6-blocking therapies in renal disease . to the best of our knowledge , little or no research has been performed so far to compare the salivary levels of il-6 and tnf- in patients undergoing hemodialysis ( hd ) with matched controls . since , the prognostic value and pathogenic role of il-6 and tnf- have been confirmed in publications , the present study aimed to investigate the salivary levels of il-6 and tnf- in patients with esrd undergoing hd . the study subject population consisted of 20 dialysis patients who were diagnosed with end - stage renal disease caused by diabetic nephropathy and admitted at nephrology department of isfahan university of medical sciences . the ethics committee of the university approved the study protocol and informed consent obtained prior to participation in this cross - sectional study . the study included 18 years or older patients who were treated with standard 4 h hd sessions , 3 times a week with low flux membrane and were stable by the time the study was conducted . the average kt / v index in patients was 1.19  0.1 and the protein catabolism index was 1.42  0.2 none of the patients suffered from any symptoms of infection or collagen vascular diseases . in all patients , patients with previous myocardial infarction , stable angina , stroke , arteriopathy and heavy smoakers were excluded . patients had not received any medications known to affect immune functions and the time period from the last blood transfusion was not shorter than 6 months . furthermore , patients with unstimulated whole saliva ( uws ) flow rates of < 0.1 ml / min were considered as salivary gland hypo - function and excluded from the study . twenty age - sex - matched healthy controls with no infectious diseases during 1 month prior to saliva collection were selected from individuals visiting oral medicine clinic of isfahan university of medical sciences . two groups were matched for gingival conditions according to modified gingival index ( mgi ) . mgi eliminates the use of probing or pressure to establish the presence or absence of bleeding . it also makes it possible to detect and record subtle visual changes in gingival inflammation , permits the intra- and inter - calibration of examiners , and is noninvasive upon repeated evaluations . participants were asked not to eat , drink , or use saliva stimulators such as chewing gum or mint for at least 1 h before sampling . participants were asked to swallow first , and then tilt their head forward and expectorate all saliva into a 50 ml centrifuge tubes for 5 min without swallowing . tnf- and il-6 , concentrations were measured using human il-6 ( sensitivity : < 0.3 pg / ml ) and tnf- ( sensitivity : < 1 pg / ml ) elisa kits ( boster biological technology co , ca , usa ) according to manufacturer 's recommendation . spss software version 18 ( spss inc . , chicago , il , usa ) was used to analyze the data . since data were normally distributed , parametric independent t - test was used (  = 0.05 ) . the study included 18 years or older patients who were treated with standard 4 h hd sessions , 3 times a week with low flux membrane and were stable by the time the study was conducted . the average kt / v index in patients was 1.19  0.1 and the protein catabolism index was 1.42  0.2 none of the patients suffered from any symptoms of infection or collagen vascular diseases . in all patients , patients with previous myocardial infarction , stable angina , stroke , arteriopathy and heavy smoakers were excluded . patients had not received any medications known to affect immune functions and the time period from the last blood transfusion was not shorter than 6 months . furthermore , patients with unstimulated whole saliva ( uws ) flow rates of < 0.1 ml / min were considered as salivary gland hypo - function and excluded from the study . twenty age - sex - matched healthy controls with no infectious diseases during 1 month prior to saliva collection were selected from individuals visiting oral medicine clinic of isfahan university of medical sciences . two groups were matched for gingival conditions according to modified gingival index ( mgi ) . mgi eliminates the use of probing or pressure to establish the presence or absence of bleeding . it also makes it possible to detect and record subtle visual changes in gingival inflammation , permits the intra- and inter - calibration of examiners , and is noninvasive upon repeated evaluations . participants were asked not to eat , drink , or use saliva stimulators such as chewing gum or mint for at least 1 h before sampling . participants were asked to swallow first , and then tilt their head forward and expectorate all saliva into a 50 ml centrifuge tubes for 5 min without swallowing . tnf- and il-6 , concentrations were measured using human il-6 ( sensitivity : < 0.3 pg / ml ) and tnf- ( sensitivity : < 1 pg / ml ) elisa kits ( boster biological technology co , ca , usa ) according to manufacturer 's recommendation . since data were normally distributed , parametric independent t - test was used (  = 0.05 ) . forty patients were enrolled in the study . the mean age of the case and control groups were 59  12.4 and 53  10.8 years , respectively . two groups were matched for mgi index ( 12 edentulous patients and 8 patients with score 3 ) . the mean amounts of tnf- and il-6 are summarized in table 1 and graph 1 . the mean amounts ( pg / ml ) of tnf- and il-6 in hd group and controls the mean amounts ( pg / ml ) of tumor necrosis factor - alpha and interleukin-6 in hemodialysis group and controls . elisa analysis of whole unstimulated saliva showed that there was a significant difference between two groups regarding the salivary levels of tnf- ( p = 0.034 ) and il-6 ( p = 0.001 ) . cytokines are soluble proteins that play an important role in the initiation and maintenance of inflammatory and immune responses . many of prior studies have found that inflammatory cytokines such as il-6 and tnf- are elevated in esrd , and some studies report salivary cytokines and secretion rates are significantly decreased in ckd patients , and recommend further research . furthermore , il-6 and tnf- are toxins which may deteriorate renal function by triggering endothelial dysfunction and glomerular injury and act as independent risk factors for mortality . we examined the salivary level of il-6 and tnf- in patients with esrd undergoing hd . our hypothesis was that there would be a significant difference in the salivary levels of these markers between hd and control groups . it was shown that salivary levels of il-6 and tnf- are significantly higher in patients with esrd undergoing hd . saliva is a safe and low - cost alternative and as a biofluid , has several advantages over blood supporting its use in diagnosis and assessment of diseases . researches have shown that levels of some serum markers like c - reactive protein , il-2 , il-6 , and tnf- correlate well with those in saliva . elevated circulating levels of il-6 in patients with congestive heart failure and active inflammation have been reported . therefore , for this study patients with any signs of cardiovascular diseases or infections were excluded . in this study , patients who received dialysis with low - flux polysulfone membrane were included . it is confirmed that the contact of blood with dialyzer membrane leads to degranulation of polymorphonuclear leukocytes and release of inflammatory mediators . furthermore , different studies assessed the back - leakage of endotoxin from the contaminated dialysate membrane , and it was found that high - flux dialyzers are the proposed mechanisms of monocyte stimulation and elevated inflammatory cytokines . therefore in the present study , patients received dialysis with low - flux polysulfone membrane . it is now well established that high prevalence of inflammatory cytokines are associated with the high rate of cardiovascular morbidity and mortality in esrd patients . increased levels of inflammatory biomarkers in esrd therefore , measurement of salivary cytokines levels may be considered as a noninvasive test for cardiac risk stratification in esrd patients undergoing hd . a number of oral diseases including lichen planus , oral cancer , and periodontal diseases have been reported to be associated with il-6 deregulation . periodontal diseases are prevalent in renal dialysis patients who showed an unacceptable level of oral hygiene and its prevalence increases with the chronicity of the illness . available literature point toward the important role of il-6 in the loss of periodontal ligament and alveolar bone through the tissue degradation effects of il-6 on connective tissue and bone , mediated by metalloproteinase and osteoclasts . according to the results of this study , elisa analysis of whole unstimulated saliva showed that difference between salivary levels of tnf- and il-6 was significant ( p < 0.05 ) and the elevated salivary levels of inflammatory cytokines may necessitate the need of comprehensive professional oral care and self - care instruction in dialysis patients . one of our restrictions in this study was sample size and in this study the correlation between salivary and serum il-6 and tnf- was not investigated ; hence , we suggest comparative analysis of salivary and serum cytokines in a larger group of patients . we would like to suggest that commenting on the viability of saliva over blood is possible only when you do a comparative analysis for both . although our findings demonstrated that salivary inflammatory biomarkers are elevated in patients undergoing hd ; however , the relation between salivary cytokine levels and the efficacy of hd has not been assessed . furthermore , it is recommended to conduct further studies to investigate the prognostic value of salivary inflammatory cytokines in cardiovascular and oral diseases . considering the significant elevation of salivary tnf- and il-6 in this study and reported role of inflammatory cytokines in the pathogenesis of cardiovascular and oral disease , our findings support the need for additional studies . if confirmed , measurement of salivary il-6 and tnf- in hd patient may be considered as a noninvasive test for cardiac risk stratification to help in risk assessment of hd patients , and in planning pertinent preventive strategies . the authors of this manuscript declare that they have no conflicts of interest , real or perceived , financial or non - financial in this article . the authors of this manuscript declare that they have no conflicts of interest , real or perceived , financial or non - financial in this article .
background : inflammatory cytokines such as interleukin-6 ( il-6 ) and tumor necrosis factor - alpha ( tnf- ) are elevated in end - stage renal disease ( esrd ) . il-6 and tnf- are toxins which deteriorate renal function , and their pathogenic role has been confirmed in cardiovascular and oral diseases . 
 this study was designed to investigate the salivary levels of il-6 and tnf- in patients with esrd undergoing hemodialysis ( hd).materials and methods : twenty patients with esrd who were treated with 4 h hd sessions , with low flux membrane were included in this cross - sectional study . 
 average kt / v index in patients was 1.19  0.1 . 
 twenty age - sex - matched healthy controls with no infectious diseases during 1 month before saliva sampling were selected . 
 unstimulated whole saliva was collected and tnf- and il-6 , concentrations were measured using human il-6 and tnf- elisa kits . 
 independent t - test was used to analyze the data using spss (  = 0.05).results : there was a significant difference between dialysis and control groups regarding the salivary levels of tnf- ( p = 0.034 ) and il-6 ( p = 0.001).conclusion : considering the results of this study and reported role of inflammatory cytokines in the pathogenesis of cardiovascular and oral diseases , measurement of salivary il-6 and tnf- in hd patients may help in risk stratification of hd patients and in planning pertinent preventive strategies .