Age and motor score predict osteoprotegerin level in chronic spinal cord injury.
OBJECTIVE
Individuals with spinal cord injury (SCI) develop a severe form of osteoporosis below the level of injury that is poorly understood. We conducted a preliminary investigation to assess whether circulating markers of bone turnover and circulating RANKL/OPG levels are related to the severity of SCI, aging, or to differences in mobility (i.e., walking or using a wheelchair).


METHODS
Sixty-four caucasian men >or=1.6 years since injury selected based on locomotive mode provided blood samples and completed a health questionnaire at the VA Boston Healthcare System from 10/2003 to 6/2005. Plasma sRANKL, osteoprotegerin (OPG), osteocalcin and carboxyterminal telopeptide of type I collagen (CTx) levels were determined.


RESULTS
Increasing age was significantly associated with increased OPG and CTx. Injury severity was predictive of OPG levels, and adjusting for age, participants with cervical motor complete and ASIA C SCI (n=11) had significantly lower mean OPG (46.1 pg/ml) levels than others (63.4 pg/ml). Locomotive mode was not associated with differences in bone markers.


CONCLUSIONS
Severe cervical spinal cord injury is associated with decreased circulating OPG levels placing these patients at risk for accelerated bone loss that appears unrelated to locomotive mode.
Morse
L R
LR
Department of Physical Medicine and Rehabilitation, Harvard Medical School and Spaulding Rehabilitation Hospital, Boston, Massachusetts 02118, USA. lmorse4@partners.org
Nguyen
H P
HP
Jain
N
N
Williams
S
S
Tun
C G
CG
Battaglino
R A
RA
Stashenko
P
P
Garshick
E
E
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging; D002908:Chronic Disease; D024042:Collagen Type I / Q000097:blood; D003920:Diabetes Mellitus / Q000453:epidemiology; D006331:Heart Diseases / Q000453:epidemiology; D006801:Humans; D006973:Hypertension / Q000453:epidemiology; D008875:Middle Aged; D009043:Motor Activity; D015675:Osteocalcin / Q000097:blood; D010024:Osteoporosis / Q000453:epidemiology / Q000378:metabolism*; D053244:Osteoprotegerin / Q000097:blood*; D010455:Peptides / Q000097:blood; D011237:Predictive Value of Tests; D053245:RANK Ligand / Q000097:blood; D012307:Risk Factors; D012720:Severity of Illness Index; D013119:Spinal Cord Injuries / Q000453:epidemiology / Q000378:metabolism*
D024042:Collagen Type I; D053244:Osteoprotegerin; D010455:Peptides; D053245:RANK Ligand; C505688:TNFSF11 protein, human; C052929:collagen type I trimeric cross-linked peptide; D015675:Osteocalcin