Table 1.

Age and partial or complete ablation of the NaPi-IIb gene have different effects on parameters controlling phosphate balance

	4-week NaPi-IIb+/−	20-week NaPi-IIb+/−	10-week NaPi-IIb−/−
Intestinal sodium-dependent phosphate transport	↓ ∼50%	↓ ∼60%	↓ ∼90%
Urinary phosphate excretion	↓	↓	↓
NaPi-IIa protein expression	↑	↔	↑
NaPi-IIc protein expression	↑	↔	↔
Serum phosphate	↓	↔	↔
FGF-23	↓	↔	↓
1,25 dihydroxyvitamin D3	↑	↔	↑

FGF-23, fibroblast growth factor 23. Data from [29–32].