Severe hypercalcemia associated with hypophosphatemia in very premature infants: a case report

Background: Severe hypercalcemia is rare in newborns; even though often asymptomatic, it may have important sequelae. Hypophosphatemia can occur in infants experiencing intrauterine malnutrition, sepsis and early high-energy parenteral nutrition (PN) and can cause severe hypercalcemia through an unknown mechanism. Monitoring and supplementation of phosphate (PO4) and calcium (Ca) in the first week of life in preterm infants are still debated. Case presentation: We report on a female baby born at 29 weeks’ gestation with intrauterine growth retardation (IUGR) experiencing sustained severe hypercalcemia (up to 24 mg/dl corrected Ca) due to hypophosphatemia while on phosphorus-free PN. Hypercalcemia did not improve after hyperhydration and furosemide but responded to infusion of PO4. Eventually, the infant experienced symptomatic hypocalcaemia (ionized Ca 3.4 mg/dl), likely exacerbated by contemporary infusion of albumin. Subsequently, a normalization of both parathyroid hormone (PTH) and alkaline phosphatase (ALP) was observed. Conclusions: Although severe hypercalcemia is extremely rare in neonates, clinicians should be aware of the possible occurrence of this life-threatening condition in infants with or at risk to develop hypophosphatemia. Hypophosphatemic hypercalcemia can only be managed with infusion of PO4, with strict monitoring of Ca and PO4 concentrations.