• calcium carbonate supplementation;
  • extremely low birthweight infant;
  • hyperparathyroidism;
  • metabolic bone disease;
  • osteopenia of prematurity


The goal of this study is to describe secondary hyperparathyroidism in extremely low birthweight (ELBW) neonates and their response to enteral calcium carbonate (CaCO3) supplementation.


A retrospective case series was conducted on extremely low birth infants, <1000 g birthweight, who survived hospitalisation, had no major congenital anomalies and had all their care in our institution


During this 6-year period, 231 ELBW infants survived hospitalisation at our institution. Of the 231 patients, parathyroid hormone (PTH) levels were performed in 66 of these patients (29%) and were elevated in 54 patients (82% of those tested). The timing of this testing was sporadic and was often performed after recognising osteopenia on radiography. Of the 54 patients with high PTH levels, 44 (81%) were treated with CaCO3 and PTH levels were monitored while on therapy. The average duration of therapy was 41 ± 28 days, with 64% of PTH levels returning to normal before discharge.


PTH is a major hormone responsible for bone resorption, and serum levels may be a useful marker in identifying ELBW neonates at risk for metabolic bone disease. ELBW neonates with secondary hyperparathyroidism may benefit from enteral supplementation with CaCO3. Further studies are needed to better evaluate the incidence, timing and potential treatment of hyperparathyroidism in ELBW infants.