Bone turnover markers and bone strength during the first weeks of life in very low birth weight premature infants.
OBJECTIVE
To determine the association between changes in bone turnover markers and bone strength of very low birth weight infants during the first eight postnatal weeks.


METHODS
Twelve very low birth weight premature infants [mean gestational age: 28.4 +/- 0.6 weeks, mean birth weight: 1131 +/- 62 grams] participated in the study. Bone strength was evaluated weekly by quantitative ultrasound measurements of tibial bone speed of sound (SOS, Sunlight Omnisense). Bone specific alkaline phosphatase (BSAP), a marker of bone formation, and carboxy terminal cross-links telopeptide of type-I collagen (ICTP), a marker of bone resorption, were collected at the ages of one, four and eight weeks.


RESULTS
BSAP increased significantly (from 119.9 +/- 16.2 U/L to 132.1 +/- 11.9 U/L and 152.1 +/- 15.7 U/L at one, four and eight weeks of life, respectively, p<0.05). ICTP decreased significantly during the study period (from 122.3 +/- 8.7 ng/ml to 96.0 +/- 4.8 ng/ml and 92.3 +/- 5.4 ng/ml at one, four and eight weeks of life, respectively; p<0.05). There was a significant decrease in bone SOS (from 2886 +/- 29 m/sec to 2792 +/- 30 m/sec and 2753 +/- 30 m/sec at birth, four weeks and eight weeks of life, respectively; p<0.02). There was no correlation between the levels of bone markers and bone SOS.


CONCLUSIONS
In VLBW premature infants, there is a significant decrease in bone strength concomitant with biochemical evidence for new bone formation (increase in BSAP and a decrease in ICTP) during the first eight postnatal weeks. Changes in the biochemical markers could not predict the changes in bone strength.
Litmanovitz
Ita
I
Department of Neonatology, Meir General Hospital, Sapir Medical Center, Kfar Saba, Israel. litmani@clalit.org.il
Dolfin
Tzipora
T
Regev
Rivka
R
Arnon
Shmuel
S
Friedland
Orit
O
Shainkin-Kestenbaum
Ruth
R
Lis
Monika
M
Eliakim
Alon
A
D000375:Aging; D000469:Alkaline Phosphatase / Q000097:blood; D001696:Biomechanical Phenomena; D001724:Birth Weight; D016723:Bone Remodeling; D001842:Bone and Bones / Q000502:physiology*; D003094:Collagen / Q000097:blood; D024042:Collagen Type I; D005865:Gestational Age; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007234:Infant, Premature; D019102:Infant, Very Low Birth Weight; D010455:Peptides / Q000097:blood; D013977:Tibia / Q000000981:diagnostic imaging; D014463:Ultrasonography
D024042:Collagen Type I; D010455:Peptides; C052929:collagen type I trimeric cross-linked peptide; D003094:Collagen; D000469:Alkaline Phosphatase