Bone acquisition and loss in children and adults with cystic fibrosis: a longitudinal study.
OBJECTIVE
To determine patterns of bone mineral acquisition in children and young adults with cystic fibrosis (CF) and to identify clinical and laboratory correlates of change in bone mineral density (BMD).


METHODS
Bone mineral and clinical status were assessed in 41 patients with CF (26 female, aged 9 to 50 years) at baseline and 1.5 years later. Bone mineral content of the lumber spine, femoral neck, and whole body was determined by dual-energy x-ray absorptiometry and expressed as BMD and bone mineral apparent density (BMAD). Changes in weight, height, pubertal status, glucocorticoid use, physical activity, disease severity, and biochemical markers of bone turnover were examined for associations with changes BMD and BMAD.


RESULTS
Mean BMD Z-scores (adjusted for age and sex) were reduced at the spine, hip, and whole body at baseline in both adults and youths, and decreased further at all sites among youths at follow-up (-0.4 at spine, p < 0.05; -0.3 at hip, p < 0.10; -0.5 for whole body, p < 0.0005). These data indicate failure to gain bone mineral at the expected rate. BMAD was also reduced at follow-up, suggesting that the observed osteopenia could not be explained by small bone size. Bone loss at multiple sites was observed in four youths and two adults. In general glucocorticoid use, change in body mass, physical activity, and disease severity were the most significant correlates for change in BMD and in BMD Z-score.


CONCLUSIONS
Osteopenia in CF generally reflects inadequate gains in bone mineral, although bone loss may occur, particularly in patients requiring glucoc therapy. Late gains in bone mineral may accompany weight gain and pubertal development, but the catch-up appears to be incomplete.
Department of Pediatrics, Stanford University of Medicine, California 94305-5208, USA.
G S
GS
Bhudhikanok
M C
MC
Wang
R
R
Marcus
A
A
Harkins
R B
RB
Moss
L K
LK
Bachrach
D000293:Adolescent; D000328:Adult; D015519:Bone Density; D001851:Bone Diseases, Metabolic / Q000150:complications* / Q000503:physiopathology; D016723:Bone Remodeling; D002648:Child; D003550:Cystic Fibrosis / Q000150:complications / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D012016:Reference Values; D012044:Regression Analysis