Fibroblast Growth Factor 23

Definition

Fibroblast Growth Factor 23 (FGF23) is a hormone primarily produced by osteocytes in the bone that plays a crucial role in phosphate metabolism and vitamin D regulation. It acts mainly on the kidneys to promote urinary phosphate excretion and inhibit the synthesis of 1,25-dihydroxyvitamin D, thereby influencing calcium homeostasis and overall mineral balance in the body.

5 Must Know Facts For Your Next Test

1. FGF23 helps regulate serum phosphate levels by promoting its excretion in the urine, thus preventing hyperphosphatemia, which can lead to bone and cardiovascular issues.
2. Elevated levels of FGF23 are often seen in conditions like chronic kidney disease, where phosphate retention becomes problematic.
3. FGF23 functions by binding to specific receptors in the kidneys, leading to changes in transporter proteins responsible for phosphate reabsorption.
4. The production of FGF23 can be influenced by dietary phosphate intake; higher intakes typically result in increased FGF23 secretion.
5. FGF23 is considered a key player in the complex interplay between bone health and mineral metabolism, particularly in the context of disorders affecting calcium and phosphate balance.

Review Questions

• How does FGF23 influence phosphate metabolism in the body?
  • FGF23 primarily influences phosphate metabolism by acting on the kidneys to increase urinary phosphate excretion. It inhibits sodium-dependent phosphate co-transporters, leading to decreased reabsorption of phosphate back into the bloodstream. This regulatory mechanism helps maintain normal serum phosphate levels and prevents conditions such as hyperphosphatemia.
• Discuss the role of FGF23 in the context of chronic kidney disease and its implications for mineral balance.
  • In chronic kidney disease (CKD), the kidneys are less able to excrete phosphate, leading to elevated serum phosphate levels. As a compensatory mechanism, FGF23 levels rise to promote urinary phosphate elimination. However, over time, persistently high FGF23 can lead to complications such as vascular calcification and contribute to bone pathology. This underscores the importance of FGF23 in maintaining mineral homeostasis during kidney dysfunction.
• Evaluate how dietary intake affects the secretion of FGF23 and its potential impact on overall health.
  • Dietary intake of phosphate has a direct impact on the secretion of FGF23. Higher phosphate consumption stimulates increased release of FGF23 from osteocytes, which promotes urinary excretion of phosphate to prevent toxicity. This relationship highlights the importance of balanced dietary phosphate intake; excessive intake can lead to elevated FGF23 levels and associated health issues like cardiovascular disease and disrupted mineral balance. Understanding this dynamic can inform dietary recommendations aimed at maintaining optimal health.

Related terms

Osteocytes:

Mature bone cells that originate from osteoblasts and are responsible for maintaining bone tissue, as well as producing factors like FGF23.

Phosphate:

An essential mineral that is vital for various biological processes, including energy production, bone formation, and cellular signaling.

1,25-Dihydroxyvitamin D: The active form of vitamin D that is crucial for calcium absorption in the intestines and plays a role in bone health and immune function.