This is a single center study randomizing patients with CKD undergoing CAG into 4 groups: 1) Intravenous normal saline, 2) Intravenous normal saline and intravenous bicarbonate, 3) oral hydration, and 4) oral hydration and oral bicarbonate. The primary endpoint was the occurrence of contrast-medium-induced nephropathy defined as greater than 25% increase in serum creatinine from baseline or an absolute increase of 0.5 mg/dL from baseline at 72 hours following exposure to radiocontrast. Secondary endpoints include the length of hospitalization and in-house mortality.