The incidence of osteopenia of prematurity in preterm infants without phosphate supplementation: A prospective, observational study

Abstract

To meet their requirements for bone mineralization, it is recommended that preterm infants receive nutritional support containing calcium and phosphate. There are no clear data on the incidence of osteopenia of prematurity (OFP) in preterm infants without phosphate supplementation.This study aimed to investigate the incidence of OFP in preterm infants without phosphate supplementation and its relationship with the duration of parenteral nutrition (PN).This was a prospective and observational study.This study included 30 infants aged <32 gestational weeks and weighed <1500 g at birth. All infants received PN according to a standard protocol, beginning on day 1 with calcium, without phosphate. Starting from the first day of life, all infants received human milk without fortifiers. Oral vitamin D (400 IU/d) was administered when enteral nutrition reached 100 mL/kg/d.The diagnosis of OFP was based on radiographs that were taken of both wrists. Serum alkaline phosphatase (ALP) was measured 3 times: at the start of PN (ALP 1), at the end of PN (ALP 2), and at discharge or the expected due date (ALP 3). Radiographs were obtained on the same day as ALP 3. The duration of PN was analyzed in the presence of OFP using receiver operating characteristic curve analysis.Among the 30 infants, 13 (43%) were diagnosed with OFP. The duration of PN was significantly longer in the OFP group than in the group without OFP (16 vs 12 days; P < .05). The provision of PN for >15 days significantly increased the risk of OFP (odds ratio, 5.40; 95% confidence interval, 1.12-26.04; P = .035).We found a high incidence of OFP in preterm infants without phosphate supplementation. An association was found between the duration of PN and the incidence of OFP. Further research is needed to prevent the development of osteopenia in preterm infants.

Figure 1

Median (range) of the duration of parenteral nutrition (days) in infants with OFP and infants without OFP (normal bone density). An independent t test showed a mean difference of 8.8 (95% confidence interval, 1.6–16; P = .018), thus indicating a significant difference between the 2 groups. Data are shown in the form of a box and whisker plot. OFP = osteopenia of prematurity.

Figure 2

Scatter diagram showing ALP levels (U/L) with parenteral nutrition duration (days). The duration of parenteral nutrition was positively and significantly correlated with ALP 2 (rho = 0.406; P = .026) and ALP 3 (rho = 0.488; P = .006). No correlation was found between the duration of parenteral nutrition and ALP 1 (rho = 0.220; P = .243). ALP 1, serum ALP activity (U/L) at the start of parenteral nutrition; ALP 2, serum ALP activity (U/L) at the end of parenteral nutrition; ALP 3, serum ALP activity (U/L) at discharge.

Figure 3

Receiver operating characteristics curve showing the duration of parenteral nutrition for detecting the existence of osteopenia of prematurity. The area under the curve was 0.667 (95% confidence interval, 0.455–0.880; P = .121). The duration of parenteral nutrition with a 15-day cutoff had a sensitivity of 69.2% and a specificity of 70.6% for the detection of osteopenia of prematurity.