Bone Growth with Low Bone Mineral Content in Very Low Birth Weight Premature Infants

Abstract

MATERIALS AND METHODSand BW at birth. Because ofthe direct relationship between BMC and BW we speculated that the ratio of BMC to BW would be useful in identifying disorders of bone mineral metabolism in low birth weight infants (I).In the present study, we report serial measurements of BMC and BW through the first 10 wk of life in 38 VLBW premature infants. We hypothesized that during this period of active growth in weight and length, BW (a measure ofbone diameter and hence of appositional bone growth in infancy and childhood) would increase secondary to increased matrix formation (2); however, we predicted BMC would decrease or remain unchanged due to insufficient mineral intake compared to that necessary to achieve the intrauterine rate of bone mineralization (l). Following entry into the study, 15 of 38 infants developed BPD and we hypothesized that as a group they could be distinguished from the 23 infants without BPD because of the high association between BPD and metabolic bone disease (3). We anticipated that the ratio of BMC to BW would be lower in the BPD group compared to controls.Population. Thirty-eight VLBW infants (birth weight < 1300 g, gestational age <32 wk) were recruited for this study during the 1st wk of life, after obtaining parental informed consent. Thirty-five infants were white and three infants were black. All infants were appropriate for gestational age. Gestational age was determined from the history of the last menstrual period and corroborated by the Ballard examination for those infants greater than 27 wk gestational age (4). For those infants less than or equal to 27 wk gestation, fetal ultrasound measurements were used as the second corroborator ofgestational age, when available from the department of obstetrics. If there was more than a 2-wk discrepancy between the two determinations of gestational age, the infant was excluded from the study. All infants were admitted to the neonatal intensive care unit at Madison General Hospital and all were free from major congenital malformations.Of these 38 infants, 15 were diagnosed subsequently as having BPD. All infants with BPD had the initial diagnosis of the respiratory distress syndrome, required supplemental oxygen for a minimum of 30 days, and had a chest x-ray diagnosis of BPD (hyperexpansion, interstitial densities, focal emphysema) (5). For purposes of comparison, the remaining 23 infants were designated as controls.Photon absorptiometry. BMC and bone width were measured by a photon absorptiometric system (Lunar Radiation Inc., Madison, WI) in which a collimated 2 mm diameter photon beam from a low activity [ 125 1] "spent source" (20-50 mCi) was passed beneath the one-third distal radius (shaft) of the left forearm. The system has been previously described in detail (1). Measurements of BMC and bone width were made within the 1st wk of life and subsequently at biweekly intervals. Accuracy, precision, and reproducibility of this system used by us in newborn infants have been published (1). Immediate reproducibility 925 Abbrevi...

Effects of motor physical therapy on bone mineralization in premature infants: a randomized controlled study

“…Previous longitudinal studies using single-photon absorptiometry confirmed the need for higher intakes of dietary calcium, phosphorus and vitamin D to improve bone mineralization in preterm hospitalized infants. 1,26 Although the positive effects of passive exercise on bone mineralization in preterm infants have been demonstrated, the American Academy of Pediatrics has stated that the nutritional goal for preterm infants is to provide optimal nutrition to support growth equivalent to in utero gain during the third trimester. Nutritional intervention, while promoting adequate weight gain, has variable effect on postnatal bone mineralization in preterm infants.…”

“…Additionally, the fracture frequency can reach 70%, especially in extreme cases involving sickly preterm infants. [1][2][3][4] The prolonged period of hospitalization of premature infants without physical stimulation may contribute to bone demineralization and can lead to changes in bone development and growth. [5][6][7][8][9] These alterations in bone development produce a reduction in both growth velocity and height, with a higher frequency of scoliosis, leg curvature and cranial deformities.…”

Maternal-administered physical activity enhances bone mineral acquisition in premature very low birth weight infants

“…17,18,23 Infants in all three groups of this study were fed an equivalent energy and nutrient intake of fortified mother's milk at recommended levels 17 and experienced an equivalent postnatal growth rate. Earlier studies 14,15,24 reported a greater rate of postnatal weight gain in preterm VLBW infants who received daily physical activity, although energy and nutrient intakes did not diminish or differ between groups.…”

“…The physical activity consisted of range of motion movements against passive resistance to all extremities as previously described. 17,18 The OT provided instruction and weekly review regarding the physical activity protocol and its administration to mothers of infants randomized to the MOM group. The infant's mother kept a diary to document administration of the physical activity program.…”

Randomized Trial of Varying Mineral Intake on Total Body Bone Mineral Accretion During the First Year of Life

“…Studies have shown lower bone mineral content (BMC) of the radius throughout the first 6 months of life of infants fed human milk compared with cow milk formula. 9,10 No studies have been reported on the effect of varying mineral intakes on total body bone mass accretion during the first year of life, which should be a better indicator of mineral nutriture. In addition, no studies have been designed in such a way as to determine whether early feeding during the first 6 months of life has a persistent effect on differences in bone mass accretion.…”