Smell, Taste, Salivary Flow, and Oral Health in Patient Receiving Dialysis: A Before and After Study.

Studies show that the change of smell and taste, also dry mouth are the most common symptoms in end stage renal disease patients, the accumulation of uremic toxins would damage the intrinsinc antioxidant systems of the olfactory epithelium and olfactory bulb, which leads to smell dysfunction compared to healthy group. Previous studies show different results about if getting rid of uremic toxins would help improve smell, even if they say olfactory identification is improved after hemodialysis episode, but there's no short term reliability of Sniffin'sticks to prove the credibility of the findings. Reduction of the whole saliva and unstimulated salivary flow rate cause dry mouth, also change oral environment, which makes dental plaque easily attach to teeth. And the accumulation of uremic in oral cavity causes oral odor, plus lack of zinc iron and reduction of saliva would affect the tastants transferred to its receptors which leads to taste dysfunction. Besides, when the patients has olfactory dysfunction, the taste will be affected as well, plus the accumulation of uremic toxin in the oral cavity also stops the conjunction of smell and taste receptors which affects taste. To understand smell, taste and oral condition in end stage renal disease patients, and due to there's no short term reliability of Sniffin'sticks, plus it's expensive and time-consuming to implement the taste assessment tool. Thus the main purpose of this study is: 1. To investigate smell and taste function, salivary secretion, oral condition, plaque index and dry mouth in end stage renal disease patients who haven't been under hemodialysis. 2. To investigate the short term reliability of Sniffin'sticks, the measuring tool of olfactory with 3-4 hours interval. 3. To investigate if Taste and Smell Survey could be the tool which detects abnormality of taste 4. To investigate the change of smell, taste and salivary secretion within 24 hours after the first episode of hemodialysis.

This is a smell, taste and oral health in patients receiving before and after hemodialysis study. End stage renal disease patients who haven't been under hemodialysis will be screened for enrollment at the nephrology department in National Taiwan University Hospital. Patients have to be over 20 years old who are diagnosed with end stage renal disease(eGFR\<15ml/min/1.73m2) but haven't been under hemodialysis yet. Expected 85 patients will be enrolled according to power analysis, those who have the diseases such as Parkinson's disease, hypothyroidism, Sjögren's syndrome, under chemotherapy or radiotherapy, history of head and neck tumour and surgery, and patients who unable to response to evaluate protocal.

We will first use Montreal Cognitive Assessment to screen patient's cognitive function, for those scored 23.5 and higher, a full evaluation will be conducted at two points in before dialysis and afterward. The full evaluation before dialysis include 1.The difference of smell, taste, salivary secretion, oral assessment guide, plaque index and xerostomia on end stage renal disease patients before and after hemodialysis. 2.Investigating the reliability of olfactory identification by using Sniffin'sticks within 2 to 4 hours. 3.Investigating the correlation between taste questionnaire and taste strips. 4.Salivary flow rate. 5.Oral Assessment Guide. 6.Plaque Index. 7.Taste threshold sensitivity.

The evaluation after dialysis involved 1.The olfactory identification 2. Salivary flow 3. Taste threshold sensitivity.For patients who get score lower than 23.5 from Montreal Cognitive Assessment, we'll skip the test of olfactory and taste .Data will be analyzed with descriptive and inferential statistics using R studio statistic software.

Eligibility Criteria:
Inclusion Criteria:

1. Diagnosed with end-stage renal disease (eGFR\<15ml/min/1.73m2) but haven't been under hemodialysis yet.
2. Over 20 years old.
3. Able to interact with instructions and communicate with others

Exclusion Criteria:

1. Those who have diseases such as Parkinson's disease, hypothyroidism, Sjögren's syndrome, under chemotherapy or radiotherapy, head and neck tumor, took head and neck surgery, unconsciousness, and cognitive dysfunction.