title: Changes in quantitative ultrasound in infants born at less than 32 weeks' gestation over the first 2 years of life: influence of clinical and biochemical changes.
abstract: Studies in preterm infants show reduced speed of sound (SOS) as measured by quantitative ultrasound (QUS) during the immediate neonatal period. There is a scarcity of data on SOS changes following hospital discharge. The aim of this study was to assess SOS over the first 2 years in preterm infants. Infants were recruited from a neonatal follow-up clinic. Tibial QUS was performed using the Omnisense 7000P scanner. Thirty-nine infants born at <32 weeks' gestation had a single SOS measurement (median 3,203 m/second, range 2,609-3,495) which correlated with corrected gestational age (CGA) (r = 0.8, P < 0.005). The majority of measurements were within the manufacturer's reference range for term infants. SOS standard deviation score (SDS) in infants aged 0-6 months CGA demonstrated a negative correlation with duration of total parenteral nutrition (r = 0.7, P < 0.05) and a positive correlation with serum phosphate (r = 0.6, P < 0.05.) Two groups of infants had serial measurements: eight had measurements performed at term CGA and early infancy (early) and seven had measurements in later infancy (late). In the early group SOS SDS increased (P < 0.005), and the greatest increase in SOS over time occurred in infants with the lowest SOS at term (r = 0.9). In the late group there was no significant change over time. SOS SDS change did not show any correlation to weight SDS change. Catch-up in SOS occurs postterm in most infants by 6 months and is independent of postnatal growth. Infants with the lowest SOS at term have the fastest rate of catch-up. The opportunity for catch-up may be greatest in early infancy.
authors.affiliation: Bone and Endocrine Research Group, Royal Hospital for Sick Children, Yorkhill, Glasgow, UK.
authors.forename: H
authors.initials: H
authors.lastname: McDevitt
authors.forename: C
authors.initials: C
authors.lastname: Tomlinson
authors.forename: M P
authors.initials: MP
authors.lastname: White
authors.forename: S F
authors.initials: SF
authors.lastname: Ahmed
mesh_terms: D000469:Alkaline Phosphatase / Q000097:blood; D001724:Birth Weight; D001846:Bone Development; D001851:Bone Diseases, Metabolic / Q000175:diagnosis / Q000000981:diagnostic imaging* / Q000453:epidemiology; D002657:Child Development; D005865:Gestational Age; D006801:Humans; D007231:Infant, Newborn; D007234:Infant, Premature / Q000097:blood / Q000254:growth & development*; D007235:Infant, Premature, Diseases / Q000175:diagnosis / Q000000981:diagnostic imaging* / Q000453:epidemiology; D008137:Longitudinal Studies; D010758:Phosphorus / Q000097:blood; D013977:Tibia / Q000000981:diagnostic imaging* / Q000254:growth & development*; D014463:Ultrasonography
chemical_list: D010758:Phosphorus; D000469:Alkaline Phosphatase