Contrast induced nephropathy is a rising cause of acute renal failure in all patients. A study published in JAMA 2004, show a superiority of a hydratation with sodium bicarbonate in comparison with the same volume hydratation with sodium bicarbonate. The investigators will try following the original protocol making 2 randomized groups of patients, with cancer diagnosis, >18 years old, with a GFR <60 and >30 ml/min/1,73m2 by MDRD formula and/or diabetic patients. In the group 1 the patients will receive a solution with 154 mEq/L of a sodium bicarbonate, 3 cc/Kg/h at 1 hour before the injection of contrast and 1 cc/Kg/h during and 6 hours before the injection. The primary end point will be the rise of 25% or more in creatinine or dialysis needed.

Inclusion Criteria:

• > 18 years old
• cancer diagnosis
• GFR < 60 and > 30 ml/min/1,73m2 by MDRD formula or diabetic
• CT with contrast

Exclusion Criteria:

• dialysis needed
• uncontrolled hypertension
• changes in serum creatinine levels of at least 0.5 mg/dl during the previous 24 hours of procedure
• recent exposure to radiographic contrast agents (within previous two days of the study)
• administration of dopamine, mannitol , fenoldopam or N-Acetyl Cystein during the intended time of study