Diagnostic approach to phosphopenic rickets

1,25(OH)2D: 1,25-dihydroxyvitamin D (calcitriol); HHRH: hereditary hypophosphatemic rickets with hypercalciuria; TIO: tumor-induced osteomalacia; TmP/GFR: maximal renal tubular threshold for phosphate, expressed per glomerular filtration rate; TRP: tubular reabsorption of phosphorus; XLH: X-linked hypophosphatemia.