CRYSVITA is contraindicated: In concomitant use with oral phosphate and/or active vitamin D analogs (e.g. calcitriol, paricalcitol, doxercalciferol, calcifediol) due to the risk of hyperphosphatemia [see Hyperphosphatemia and Risk of Nephrocalcinosis under Precautions and Oral Phosphate and Active Vitamin D Analogs under Interactions]; When the serum phosphorus is within or above the normal range for age [see Hyperphosphatemia and Risk of Nephrocalcinosis under Precautions]; In patients with severe renal impairment or end stage renal disease because these conditions are associated with abnormal mineral metabolism [see Renal Impairment under Precautions].