Original Article

Osteoporosis International

, Volume 24, Issue 4, pp 1333-1338

Low bone turnover and low bone density in a cohort of adults with Down syndrome

  • K. D. McKelveyAffiliated withDepartment of Family Medicine, University of Arkansas for Medical SciencesDepartment of Medical Genetics, University of Arkansas for Medical Sciences Email author 
  • , T. W. FowlerAffiliated withDepartment of Physiology and Biophysics, University of Arkansas for Medical SciencesDepartment of Orthopaedic Surgery, Center for Orthopaedic Research, University of Arkansas for Medical Sciences
  • , N. S. AkelAffiliated withDepartment of Physiology and Biophysics, University of Arkansas for Medical Sciences
  • , J. A. KelsayAffiliated withDepartment of Medical Genetics, University of Arkansas for Medical Sciences
  • , D. GaddyAffiliated withDepartment of Physiology and Biophysics, University of Arkansas for Medical SciencesDepartment of Orthopaedic Surgery, Center for Orthopaedic Research, University of Arkansas for Medical Sciences
  • , G. R. WengerAffiliated withDepartment of Pharmacology and Toxicology, University of Arkansas for Medical Sciences
  • , L. J. SuvaAffiliated withDepartment of Physiology and Biophysics, University of Arkansas for Medical SciencesDepartment of Orthopaedic Surgery, Center for Orthopaedic Research, University of Arkansas for Medical Sciences

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Abstract

Summary

Increased incidence of osteoporosis in Down syndrome has been reported, but etiology is not established. We report low bone turnover markers and bone mineral density (BMD) in a cohort of people with Down syndrome without consistent clinical risk factors. Our results should guide future studies and treatments for this common problem.

Introduction

To better understand the etiology for osteoporosis in Down syndrome (DS), we measured bone density by dual-energy X-ray absorptiometry (DXA) and circulating biochemical markers of bone formation and resorption in a cohort of 30 community-dwelling DS adults.

Methods

Seventeen males and 13 females followed in the University of Arkansas Down Syndrome Clinic were evaluated by DXA to estimate BMD and underwent phlebotomy to measure serum procollagen type-1 intact N-terminal propeptide (P1NP) to evaluate bone formation, and serum C-terminal peptide of type-I collagen (CTx) to evaluate bone resorption.

Results

Seven of 13 DS females and 12 of 17 DS males had low bone mass at one of measured sites (z ≤ −2.0). When data were grouped by age, males had apparent osteopenia earlier than females. The mean P1NP in the normal group was 19.2 ± 5.2 ng/ml vs. 2.2 ± 0.9 ng/ml in the DS group (P = 0.002). Serum CTx levels in the normal group were 0.4 ± 0.1 ng/ml vs. 0.3 ± 0.1 ng/ml (P = 0.369).

Conclusions

Low BMD in adults with DS is correlated with a significant decrease in bone formation markers, compared to controls without DS, and is independent of gender. These data suggest that diminished osteoblastic bone formation and inadequate accrual of bone mass, with no significant differences in bone resorption, are responsible for the low bone mass in DS. These observations question the use of antiresorptive therapy in this population and focus attention on increasing bone mass by other interventions.

Keywords

Bone density Bone turnover Down syndrome Osteopenia Osteoporosis Trisomy 21