To the Editor.
—In the April 1980 Archives (140;531-533), Fang et al underlined the low fractional excretion of sodium (FENa) values that they found in all 12 cases of contrast media-induced acute renal failure; they said this finding is characteristic of contrast media-induced acute renal failure.We would like to juxtapose our findings in an already presented prospective study.1 In this study, we found that in five of seven cases of acute renal failure caused by contrast media, the FENa values fluctuated definitely above 1. In fact, in two of our patients, the FENa values were 6.89 and 6.95, respectively.The two patients with FENa values below 1 had less serious clinical features. The biochemical disturbances, on the other hand, lasted for only 24 hours. The only oliguric patient belonged to the group with high FENa values, while all the rest of the patients