Contrast media can lead to renal impairment that results in longer hospitalization and increased mortality. Adenosine is a crucial mediator of contrast-induced nephropathy (CIN; an increase in serum creatinine of >or=0.5 mg/dl within 48 hours). Therefore, it was the purpose of our study to investigate whether the adenosine antagonist theophylline reduces the incidence of CIN after coronary angiography. We also characterized risk factors for CIN after coronary angiography. One hundred patients with serum creatinine concentrations of >or=1.3 mg/dl randomly received 200 mg IV theophylline or placebo 30 minutes before coronary angiography (amount of contrast medium >or=100 ml). Patients who received theophylline and the controls were comparable with regard to baseline creatinine levels (means +/- SD) (1.65 +/- 0.41 vs 1.72 +/- 0.69 mg/dl) and the amount of contrast medium received (235 +/- 89 vs 261 +/- 139 ml). Theophylline significantly reduced the incidence of CIN (4% vs 20%, p = 0.0138). With placebo, creatinine significantly increased at 12 (1.82 +/- 0.79 mg/dl, p = 0.0057), 24 (1.90 +/- 0.86 mg/dl, p = 0.0001), and 48 hours (1.90 +/- 0.89 mg/dl, p = 0.0007) after administration of contrast medium. With pretreatment with theophylline, mean creatinine only increased 24 hours after contrast medium administration (1.70 +/- 0.40 mg/dl, p = 0.029), but was stable 12 hours (1.65 +/- 0.43 mg/dl, p = 0.99) and 48 hours after contrast medium administration (1.65 +/- 0.41 mg/dl, p = 0.99). The following parameters were significantly associated with contrast-induced renal impairment: Cigarroa quotient >5 (contrast medium [milliters] x serum creatinine/body weight [kg]), elevated troponin T, >300 ml of contrast medium, and emergency angiography. In conclusion, theophylline reduces the incidence of CIN in patients with chronic renal insufficiency undergoing coronary angiography. It should be used especially in patients receiving large amounts of contrast medium, and in patients with a Cigarroa quotient of >5 and/or elevated troponin T levels.