Figure 1. Simplified diagram showing muti-organ interactions in regulation of phosphate homoeostasis.
FGF23 produced in the bone cells can suppress renal NaPi-2a and NaPi-2c co-transporter activities to increase the urinary excretion of phosphate. Likewise, FGF23 can also suppress renal expression of 1α(OH)ase to reduce production of 1,25(OH)2D (1,25-dihydroxyvitamin D), which can suppress intestinal NaPi-2b activities to reduce phosphate absorption, resulting in decreased serum phosphate levels [6].