Cases of increased serum calcium, including severe hypercalcemia and/or increased parathyroid hormone levels, have been reported in patients treated with burosumab (Crysvita) particularly in patients with tertiary hyperparathyroidism.

Regular monitoring of serum calcium and parathyroid hormone levels is recommended:

•    before initiation of treatment, 
•    1-2 weeks after initiation and dose adjustments 
•    every 6 months (every 3 months for children aged 1-2 years)

Factors such as hyperparathyroidism, prolonged immobilisation, dehydration, hypervitaminosis D or renal impairment may increase the risk of hypercalcaemia.

The product information is being revised to include this new information.

Healthcare professionals are reminded of the importance of reporting suspected adverse reactions in order to monitoring drug safety and protecting patient health.