Comparative Study of the Efficacy of Oral Versus Intravenous Hydration as a Preventive Measure of Contrast-induced Nephropathy (CIN) in Patients With Renal Insufficiency (RI) Grade III Under Study Conducting Computed Tomography (CT)

Inclusion Criteria: * Patients of both sexes over 18 years * Candidates for a study with computed tomography and intravenous contrast * A glomerular filtration rate between 30 and 45 mL / min including both determinations * They have signed the written informed consent after being informed of the objectives and the nature of the case or be unable to have the authorization or agreement of its Exclusion Criteria: * refuse to participate in the study * pregnancy or lactation * Other risk factors for Contrast Induced Nephropathy: diabetes mellitus type I, have an age of 75 years or above, heart failure (defined by a scale New York Heart Association 3 or 4), hypotension (defined as systolic blood pressure \<100), being treated with nephrotoxic medications. * Any disease or a history that, in the investigator's opinion, could confound the results of the study or pose an additional risk to patient treatment.