The stronger increase in urinary Ca2+ excretion in the NaPi-IIb−/− mice during LPD suggested bones as source for Pi: although a drastic  hypercalciuria was observed in both genotypes when fed a LPD (both 3 and 14 days), urinary Ca2+ levels were more than 70% higher in NaPi-IIb−/− mice than in their WT littermates. This evidence concerns the gene SLC34A2 and Hypercalciuria.