Study group was composed of vitamin D deficient females (n =18, mean age 29.1±9.9 yrs), vitamin D sufficient healthy females (control group; n = 19, mean age 28.5±5.2 yrs) and patients with genetically-determined hypophosphatemic rickets (n=13, mean age 26.5±15.1 yrs). Groups were compared for serum FGF-23, 1,25 dihydroxy vitamin D3, calcium, phosphate, bone turnover markers, intact parathyroid hormone and urinary excretion of calcium and phosphate. Vitamin D deficient group was re-evaluated after a standard treatment regimen.