Fibroblast growth factor 23 (FGF23) is primarily produced by osteocytes, which are specialized cells residing within the bone.
FGF23 plays a crucial role as a hormone that helps regulate the body's phosphate levels. Its production by osteocytes allows it to act as a systemic factor, traveling through the bloodstream to influence distant organs.
Understanding FGF23 and its Origin
Osteocytes, the most abundant cells in mature bone tissue, are key players in sensing mechanical stress and regulating bone remodeling. Beyond these functions, they also serve as the main source of FGF23. Once produced, FGF23 targets the kidneys to manage phosphate excretion and vitamin D metabolism, essential processes for maintaining mineral balance.
Here's a quick overview of FGF23's key aspects:
| Aspect | Detail |
|---|---|
| Source | Osteocytes (cells found in bone) |
| Function | Regulator of phosphate homeostasis |
| Target Organ | Kidney |
| Clinical Relevance | Elevated levels observed systemically and in osteocytes in chronic kidney disease patients and models |
Role in Phosphate Homeostasis
FGF23 is a vital component of the intricate system that maintains phosphate balance in the body. When phosphate levels in the blood rise, osteocytes release FGF23. This hormone then signals the kidneys to increase phosphate excretion in the urine and to decrease the production of active vitamin D, which in turn reduces intestinal phosphate absorption. This mechanism helps prevent excessive phosphate accumulation, which can be detrimental to various bodily functions.
FGF23 and Chronic Kidney Disease
In conditions like chronic kidney disease (CKD), the body's ability to excrete phosphate is impaired. As a compensatory mechanism, FGF23 levels can become significantly elevated, both systemically throughout the body and specifically within the osteocytes themselves. While this initial increase in FGF23 helps to mitigate phosphate retention, chronically high levels are associated with negative health outcomes and can contribute to the progression of kidney disease and bone disorders. The sustained elevation of FGF23 is considered an early marker of phosphate dysregulation in CKD, highlighting the critical link between bone, phosphate metabolism, and kidney health.
