Phosphorus works together with calcium to make up strong, healthy bones and teeth.  Most phosphorus stored in the body is found in the bones, but some is present within the blood, where it is known as phosphate, an electrolyte. Phosphate works with calcium to aid in neural and muscular energy.

Phosphate regulation

Phosphate levels in the blood impact calcium levels in the blood because phosphate attaches to calcium. This, then, reduces the amount of readily available, circulating calcium. In other words, when phosphate levels rise, calcium levels fall. 





The Kidneys

Because calcium is our most critical electrolyte, the calcium feedback mechanism is crucial to maintaining homeostasis (balance). The kidneys play a significant role in this process. When the parathyroid glands release parathyroid hormone (PTH) to stimulate the bones to release calcium, this same hormone also stimulates the kidneys to reabsorb calcium, convert vitamin D3 to calcitriol, and eliminate phosphorus through urinary waste. 

Phosphorus and Hypoparathyroidism

Without PTH, the kidneys are not given the signal to eliminate phosphorus from the blood. If phosphorus levels in the body are high, absorption of oral calcium is limited, which increases symptoms related to hypocalcemia. In addition, phosphorus binds with calcium, and over time high phosphorus levels can lead to calcium deposits on the kidneys (kidney stones), brain, or other areas of the body. For this reason, it is important for people living with chronic hypoparathyroidism to monitor their kidney function regularly.  

This image contains a diagram of the calcium regulation process, involving the parathyroid glands, kidneys, small intestines, and bones

Click the picture above to get a better look at the role of the kidneys in calcium and phosphorus balance.