Final answer:
Calcium carbonate is correctly indicated as being used as a phosphate binder to treat hyperphosphatemia, particularly in patients with renal failure, by forming insoluble calcium phosphate composites that are then excreted.
Step-by-step explanation:
The statement about calcium carbonate being used as a phosphate binder to treat hyperphosphatemia is TRUE. Calcium carbonate's chemical formula is indeed CaCO₃, and it can be used to lower phosphate levels in the blood for people with kidney failure or related conditions. When calcium carbonate interacts with phosphate in the blood, it forms insoluble calcium phosphate, which is then excreted, helping to reduce the phosphate levels in the body.
Hyperphosphatemia can occur when there is decreased renal function, which may prevent the kidneys from excreting excess phosphate. In the context of renal failure, the conservation of phosphate by the kidneys is compromised, leading to elevated phosphate levels in the blood. Treatment with calcium carbonate helps to bind the excess phosphate and remove it from circulation.