Premature babies with a gestational age of ≤32 weeks and/or a
birth weight of ≤1 500 g who were hospitalized in the neonatal intensive care unit between June 2009 and March 2011 were included in the study. These babies were evaluated at the 40th gestational week and serum
calcium,
phosphorus,
alkaline phosphatase,
urea,
creatinine, urinary
calcium and
phosphorus levels were measured and tubular reabsorption of
phosphorus was determined. The subjects who had bone graphy findings and/or an
alkaline phosphatase level of >400IU/L and a
phosphorus value of <3.5 mg/dL were considered osteopenic. The levels of tubular reabsorption of
phosphorus of the osteopenic patients were compared with the ones of the non-osteopenic patients. The study was initiated after obtaining ethics committee approval (date: 04.29.2009/213).
RESULTS: During the study period, a total of 698 premature babies were hospitalized in our neonatology unit. A diagnosis of
osteopenia of prematurity was made in 24 of 190 subjects who met the study criteria. The level of tubular reabsorption of
phosphorus was compared with the serum
calcium,
phosphorus and
alkaline phosphatase levels measured at the 40th gestational week and
alkaline phosphatase was found to be significantly increased in the group with a high tubular reabsorption of
phosphorus (≥%95). When the subjects with a
phosphorus level of <3.5 mg/dL and an
alkaline phosphatase level of >499 IU were compared with the newborns who were found to have a tubular reabsorption of
phosphorus of ≥%95 for the objective of evaluating the specificity and sensitivity of tubular reabsorption of
phosphorus, the sensitivity, specificity, positive predictive value and negative predictive value of tubular reabsorption of
phosphorus in the diagnosis of
osteopenia were found to be 27%, 82%, 17% and 89%, respectively. When the osteopenic and non-osteopenic patients were compared in terms of the levels of tubular reabsorption of
phosphorus, no statistically significant difference was found.
CONCLUSIONS: