Hypercalcemia is a frequent side effect of 13-cis-retinoic acid treatment in patients with high-risk neuroblastoma.

In this cohort, grades 3 and 4 hypercalcemia were observed more often than previously reported. A single kidney and pretreatment with myeloablative chemotherapy with stem cell transplantation were identified as potential risk factors for the development of hypercalcemia.