They can be affected by high calcium oxalate intake as oxalates will causes crystals in the kidneys just as easily as it mineralizes the heart, lungs, liver, muscles and joints, but it does not target the kidneys. If the organ function cannot be restored, or the degeneration halted when there is still enough left to support sufficient functioning, the animal dies. Kidneys are also affected by the body's fluid volume. If sustained over the long term, it causes kidney failure. This problem can be compounded in iguanas and other reptiles through the use of antibiotics, many of which are already hard on the kidneys.
Fluid volume has nothing to do with oxalates nor with goitrogens and hypothyroidism.
There is a nonfat tofu cake available that would be great for use except for the other problem associated with tofu. Tofu contains goitrogens, phytocompounds which interefere with the thyroid gland's uptake of iodine from the diet. When fed in excess, vegetables including broccoli, Brussels sprouts, kale, cabbage, cauliflower, and bok choy cause hypothyroidism, a thyroid deficiency. This slows down the metabolism, causes lethargy, and muscle and joint aches. The animal gains weight due to the slowed metabolism and lowered activity levels, but overall growth is abnormally slowed.