This is an excessive amount for the kidney patient. The reason why has to do with a compound called oxalate. Kidney patients already have high levels of oxalate, and too much supplemented vitamin C increases it. Oxalate accumulates in the blood and is not dialyzed off. Oxalate crystals can form in bones and smooth muscle, including the heart, causing muscle weakness and loss of function.
Arthritis is another potential consequence of oxalate accumulation.
Kidney patients should take the recommended daily amount of vitamin C, which is 60 mg, but no more. For kidney patients, the more vitamin C consumed, the higher the risk of oxalate deposits in important tissues. Only Vitamins formulated specifically for kidney patients contain the correct amount of vitamin C, as well as the B vitamins.