To the Editor: A higher risk of metabolic bone disease (MBD) of prematurity is associated with a lower gestational age (GA) and birth weight (BW) [1, 2]. We aimed to test serum alkaline phosphatase (ALP) levels in order to provide a simple and early biomarker for prevention of MBD before the first radiological signs of osteopenia. We conducted a noninterventional study with prospective recording of data within very-low-BW (< 1500 g) neonates with no changes to routine clinical care. Biological MBD (bMBD) was defined as ALP levels greater than 600 UI/L at day of life (DOL) 30.

Nine of the 30 neonates (30%) were diagnosed with bMBD. All were born before 29 wk and had a BW below 1000 g. They were significantly born at a lower GA (26.8 vs. 29.0 wk, p = 0.01) and with a lower BW (805 vs. 1084 g, p = 0.04) than neonates without bMBD. Nutritional intakes during hospitalization complied with European recommendations [3]. There was no statistically significant difference in calcium and phosphorus intakes between the bMBD and the no bMBD groups. At DOL 15, ALP levels were already significantly higher in the bMBD group (690 vs. 393 IU/L, p < 0.001). Urinary assessments exhibited no difference in calcium and phosphate excretion between the two groups.

MBD management is above all preventive and mainly through the optimization of nutritional intakes (caloric, phosphorus and calcium). Our results showed that the strict respect for nutritional guidelines did not prevent bMBD in high-risk patients. We would suggest starting the screening for MBD from DOL 15 with serum ALP levels greater than 500 UI/L. Therefore, treatment based on supplementation with phosphorus and/or calcium (to reach total intakes of 90 and 150 mg/kg/d, respectively), as suggested in previous studies [1, 4], could be administered earlier to the patients exhibiting biological signs of ongoing MBD.