End stage renal disease (ESRD) is a severe clinical state of irreversible loss of endogenous kidney function, shortening life expectancy, if left untreated. In the state of ESRD, over 5000 uremic toxins are accumulated in the body causing dysfunction of various organ systems. The survival of these patients depends on renal replacement therapies, such as hemodialysis (HD), which artificially purifies the blood from toxins. The investigators assume that some of the uremic toxins are also present in the patient's exhaled breath, and could be detected by a non-invasive and highly sensitive test: a NA-NOSE artificial olfactory system. It is based on analysis of volatile organic compounds (VOCs), a novel, non-invasive field in medical diagnostics. The NA-NOSE is made from an array of nanosensors, and was developed by our collaborator Dr. Hossam Haick (Chemical Engineering, Technion).

In the current study, the investigators utilize this technology to identify VOCs in the exhaled breath of dialysis patients, and to characterize certain patterns of expression that could potentially help in future monitoring of HD adequacy. The investigators plan to collect 150 breath samples from patients before and during dialysis, and from healthy subjects. All participants provide a signed informed consent. Subsequently, analysis of samples will be done at Dr. Haick's laboratory, using Gas-Chromatography/Mass-Spectrometry and parameters extracted from each sensor response.

Inclusion Criteria:

• 18 Years and older
• End stage renal disease receiving hemodialysis

Exclusion Criteria:

• Age under 18
• Pregnancy
• Malignancy
• Infectious diseases

Hemodialysis patients