Contrast Nephropathy is the third cause of acute kidney injury in hospitalized patients. The morbidity and mortality of this disorder is considerable. There is no treatment for this condition and all measures should be taken into account to prevent this complication. Among the all prophylactic measures hydration and the dose ant type of contrast are the only factors that have been proved to be effective in preventing contrast nephropathy. N-Acetyl Cystein is an antioxidant agents that may be effective in different aspects of medicine, but it,s use in this condition is controversial. While some studies showed it is effective in prevention of contrast nephropathy, others showed no benefit. Different studies used different dose and route of administration. So more clinical trials with good power are needed to compare different oral Vs IV administration of the drug in a randomized double blinded clinical trial. In this study we allocate the eligible patients with chronic kidney diseases stages 2 to 4 to three groups. Oral N-Acetyl Cystein group, IV N-Acetyl Cystein group, placebo group. All group will be matched according to stages of chronic kidney diseases, diabetes, anemia, heart failure, age and sex.
