Effect of phototherapy on calcium metabolism and bone mineral density in full-term neonates (Pilot study)

Abstract Background Jaundice is a common cause of morbidity in the first week of life. Phototherapy (PT) has a considerable role in the management of hyperbilirubinemia in newborns. Hypocalcemia is an uncommon but possible complication of phototherapy (PT). Suppression of the pineal gland, suppression of parathormone hormone (PTH) secretion and increased urinary calcium (Ca) excretion are the proposed mechanisms for hypocalcaemia development after phototherapy. Aim Our objective was to investigate whether phototherapy is associated with measurable changes in calcium-phosphate metabolism, bone mineral density, and body composition during the early neonatal period in full-term neonates. Methods This study included 40 full term newborns divided into 2 groups 20 cases and 20 controls aged from 2 to 8 days. DXA scan was done at base line and at one month later using lunar prodigy primo (GE healthcare) for both cases and controls. They were examined for the effect of PT on serum levels of calcium, magnesium, phosphorus, vitamin D, parathyroid hormone, and alkaline phosphatase (ALP) at base line and after 48 h of phototherapy. Results The incidence of hypocalcemia increased from 15% pre phototherapy to 21.1% post phototherapy though non-significant. No statistical significant difference in median serum magnesium, alkaline phosphatase and vitamin D between pre and post PT. There was significant decrease in mean serum phosphorus in follow up lab in both study groups. There was significant decrease in Arms and L1-4 BMD post phototherapy. Conclusion Phototherapy was associated with a decrease in Arms and lumbar spine (L1–L4) BMD in full-term neonates, with no significant change in serum calcium. These findings are exploratory and should be confirmed by larger prospective studies.