How does chronic kidney disease (CKD) impact calcium and phosphorus balance?

In chronic kidney disease (CKD), the kidneys become less effective at filtering and excreting waste products, which significantly affects the balance of calcium and phosphorus in the body. As kidney function declines, phosphorus excretion is impaired, leading to an accumulation of phosphorus in the bloodstream. This results in hyperphosphatemia, a condition characterized by elevated serum phosphorus levels.

Simultaneously, CKD can lead to reduced levels of active vitamin D (calcitriol), which plays a crucial role in calcium absorption in the intestines. With decreased calcium absorption, serum calcium levels tend to drop, resulting in hypocalcemia. The disturbance in calcium and phosphorus balance is further compounded by the fact that elevated phosphorus levels can contribute to the development of secondary hyperparathyroidism, where parathyroid hormone (PTH) levels increase in response to low calcium levels and high phosphorus levels.

This interaction highlights the relationship between kidney function and mineral metabolism, leading to the conclusion that in CKD, phosphorus levels rise while calcium levels drop, confirming the accuracy of the provided answer. This imbalance necessitates careful management of dietary intake of these minerals and the use of phosphate binders or vitamin D analogs in some cases to restore balance and prevent complications such as bone disease