dyes used during imaging tests of the kidneys can sometimes
lead to kidney failure and nearly always result in reduced
kidney function, but the results of a new study show that
popular antioxidant, N-Acetyl Cysteine (NAC), greatly reduces
The dye is injected
into the body, and within a few minutes, it accumulates in
the kidneys. Then an X-ray picture can be taken that will
show the structure of the kidneys.
But the dye can
lead to kidney damage or failure in some people, particularly
those with existing kidney problems. Patients with diabetes
and existing kidney may have as much as a 50% chance of kidney
think that the damage is inflicted by oxidation, which causes
NAC is used to
treat several types of lung disease as well as to treat people
who have overdosed on acetaminophen, the active ingredient
in pain relievers like Tylenol.
The study included
83 people with kidney problems who were randomly assigned
to receive NAC before and after injection with a dye or to
receive a placebo. Based on several measures of kidney function,
people taking NAC were less likely to experience kidney damage.
to prevent dye-related kidney damage in the past have been
unsuccessful, so the results of this study are "encouraging,"
according to the researchers.
editorial refers to this treatment as a "decidedly low-technology
approach". It also notes that diabetes also increases
the risk of kidney damage, so it would be a good idea to study
the effects of NAC in diabetics.
NAC may also increase
the biologic effects of nitric oxide by combining with it
to form S-nitrosothiol, which is a more stable form and a
potent vasodilator. This interaction may also limit the production
of the damaging peroxinitrite radical, since NAC would compete
with the superoxide radical for nitric oxide. NAC also increases
the expression of nitric oxide synthase and may thus improve
blood flow as well.
note that proper hydration is another factor which can help
protect the kidneys.
New England Journal of Medicine
July 20, 2000;343:180-184,210-212.