Sales of Genzyme's Renagel sevelamer phosphate binder, which is marketed to lower plasma phosphorus levels in patients on dialysis, have grown dramatically since the company began presenting data showing that the alternative - inexpensive calcium tablets like Tums - can cause cardiovascular calcification. From 1999 sales of $20 million, sales grew to $56 million in 2000 and are projected to hit $120-$130 million this year.

But just as Renagel proves that it is better than calcium, it is likely to face new competition from Shire Pharmaceuticals Group plc