Use of Calcitonin for Hypercalcemia in a Premature Neonate With Congenital Mesoblastic Nephroma.

We report on a premature neonate (31 4/7 weeks' gestation) who presented with hypercalcemia secondary to congenital mesoblastic nephroma (CMN), the most common type of renal tumor in neonates. Typical presentation includes a palpable abdominal mass or swelling and may include abdominal pain, hematuria, fever, or hypertension. A less common complication of CMN is hypercalcemia of malignancy. Although the primary management strategy for hypercalcemia of malignancy is to treat the underlying disease, there are several agents that can be used as well for acute hypercalcemia including fluids, loop diuretics, corticosteroids, bisphosphonates, and calcitonin. However, there is minimal evidence to guide efficacious and safe treatment selection and dosing as hypercalcemia is a rare complication of this tumor type. This case adds to the current body of literature as only the second case of parathyroid hormone-related peptide-mediated hypercalcemia in a preterm neonate treated with calcitonin and is the first to specify a successful dose escalation strategy of calcitonin for this indication.