Vitamins and minerals are substances contained in our food that help our body function properly. Кidneys play an important role in maintaining bone strength by balancing the levels of phosphorus and calcium in the blood. Phosphorus is the second most common mineral in the human body, with approximately 85 percent of it found in bones. It is key to the water-electrolyte balance in the body and has extremely important functions for the formation of healthy bones and teeth. It is an integral part of the molecule adenosine triphosphate (ATP), which is the main structure that stores energy in the body, in the structure of DNA and RNA molecules, as well as in the formation of cell membranes.
Phosphorus is absorbed in the small intestine and stored in the bones. It is absorbed by the intestinal epithelium and its homeostasis depends on the kidneys. Therefore, disturbances in phosphate levels are most often due to disturbances in renal function. It is recommended that healthy adults receive between 800 mg and 1200 mg of phosphorus each day. Damaged kidneys do not eliminate enough phosphorus in the urine, which increases the levels of phosphorus in the blood – called hyperphosphatemia.
Because phosphorus is abundant in most foods, its deficiency is rare. Its high content in the blood is more common. Due to the delicate balance between phosphorus and calcium that needs to be maintained, consuming too much phosphorus without adequate dietary calcium intake can have negative consequences.
Phosphorus, calcium, vitamin D and parathyroid hormone (PTH) and their interaction with the kidneys play a role in controlling the level of phosphorus in the blood.
When the kidneys are functioning properly, they maintain phosphorus and calcium in balance in the blood. The kidneys also convert vitamin D into an active hormone (calcitriol), which helps increase the absorption of calcium from the gut into the bloodstream. When the level of calcium in the blood is low, the parathyroid glands (four small glands in the neck) produce more PTH. This causes calcium to be drawn from the bones into the bloodstream. Elevated levels of parathyroid hormone can cause bone problems called renal osteodystrophy.
When there is a kidney problem, high levels of phosphorus in the blood (hyperphosphatemia) are a problem for people with stage 4 and 5 kidney disease, especially stage 5 (also known as end-stage kidney disease or ESRD).