I understand that Iressa tends to lower magnesium. My mother is almost 90 and she has been taking Iressa since she was diagnosed stage four lung cancer almost five years ago. She still walks more than a half mile every day. Her magnesium level is 1.8mg/dl. She occasionally expels some 100% uric acid bladder stones which causes no pain. Her other medications are Fosamax and Glyburide. Calcium citrate and vitamin supplement pills bother her stomach. She has started eating a cereal that claims one portion contains 25% of the magnesium daily requirement. Is that enough? If you advise that she should take a supplement, can it be in liquid form? There is a liquid vitamin product that claims that one tablespoon contains 75% of the daily requirement for both magnesium and calcium. Could that formula worsen her bladder stone problem?