Controlling serum
phosphorus levels in patients with
renal failure is critical. The use of oral
phosphate-binding agents is universal for patients with
end-stage kidney disease to reduce
phosphate absorption. The therapeutic goal is to reduce serum
phosphorus levels without disturbing
calcium homeostasis or promoting accumulation of potentially toxic elements from the medication.
Aluminum hydroxide effectively reduces serum
phosphorus, but has largely been abandoned as a first-line
phosphate binder because of hazards associated with
metal absorption and tissue accumulation. Traditional
calcium-based
phosphate binders tend to promote
hypercalcemia and
calcium overloading, and are linked to accelerated cardiovascular calcification. Interest in
aluminum-free,
calcium-free
phosphate-binding agents continues to grow.
Sevelamer hydrochloride, a
metal-free,
calcium-free
hydrogel, is not absorbed, has been proven safe and efficacious in controlling serum
phosphorus, and is associated with attenuated progression of cardiovascular calcification.
Lanthanum carbonate is a newer
aluminum-free,
calcium-free
phosphate-binding agent.
Lanthanum is a rare-earth trace
metal with industrial and agricultural applications. As a therapeutic, this
metal-based binder appears effective in reducing serum
phosphorus, yet concerns remain about
lanthanum accumulation in tissues during long-term
oral administration. Similar to the
metal aluminum,
lanthanum is absorbed in the intestine and accumulates in body tissues, especially in the liver, bone, muscle, kidney, and brain. Moreover, the rate of intestinal absorption of
lanthanum is enhanced in
chronic renal failure. Our experience with
aluminum hydroxide suggests caution regarding the long-term use of another
metal-based agent that displays enhanced absorption in the uremic state and progressive tissue accumulation.