Objective The aim of this study was to evaluate the value of tubulary phosphorus reabsorption (TPR) ratio in diagnosis of osteopenia of prematurity.

Methods This prospective study was performed between June 2009 and March 2011 and premature infants < 32 weeks of gestation and/or < 1500 gram were included. Maternal and neonatal demographic data were all recorded. The plasma Ca, P, ALP and 25-OH vitamin D levels of mothers and infants were evaluated. The neonatal morbidities, duration of hospitalizati, on and total parenteral nutrition were also recorded. Infants were evaluated at postnatal 40th week. Bone mineralization was assesed by plasma Ca, P, ALP, urea, creatinine and GGT levels in combination with femur X-ray. Also, urine was collected to determine urinary Ca and P levels and tubulary phosphate reabsorption was calculated.

Results No significant differences were detected between infants with and without osteopenia of prematurity in terms of maternal biochemical values. On the postnatal 40th week, infants with TPR>95% had significantly higher ALP and lower P levels compared with those who had lower TPR. The sensitivity, specificity, positive predictive value and negative predictive value of TPR ratio in diagnosis of prematurity of osteopenia were found to be 27.2%, 82.7%, 17.1% and 89.6%, respectively.

Conclusion In conclusion, TPR ratio can be used as an ancillary diagnostic marker in addition to primary diagnostic tests in diagnosis of prematurity of osteopenia.