TitleBetween-subject and within-subject variability in measures of biochemical markers of bone turnover in cynomolgus and rhesus macaques.
Publication TypeJournal Article
Year of Publication2021
AuthorsSattgast, L, Branscum, AJ, Jimenez, VA, Newman, N, Grant, KA, Turner, RT, Iwaniec, UT
JournalBone Rep
Date Published12/2021


  • We evaluated variation in plasma osteocalcin and CTX in non-human primates.
  • Osteocalcin was higher in males and in rhesus than in cynomolgus macaques.
  • No sex or species differences were detected for CTX.
  • There was considerable within-subject variation in levels of osteocalcin and CTX.
  • Osteocalcin and CTX were stable across subjects during a 4-month time interval.


Development of optimal bone mass during early adulthood is determined by the balance between bone formation and resorption. The utility of minimally invasive biomarkers for monitoring bone turnover balance in maturing non-human primates has received limited attention. This study evaluated the biological variation of osteocalcin (a marker of bone formation), carboxyterminal cross-linking telopeptide of type 1 collagen (CTX, a marker of bone resorption), and the ratio of osteocalcin to CTX (reflecting bone turnover balance), in 136 rhesus and cynomolgus macaques aged 3.8-11.6 years. In a subsample of the animals (n = 28), blood samples were collected at monthly intervals over 4 months. Between-subject analysis revealed that there were no sex or species differences for CTX. Osteocalcin and the ratio of osteocalcin to CTX were higher in males than in females, and in rhesus macaques than in cynomolgus macaques. There were no changes in osteocalcin, CTX, or the ratio of osteocalcin to CTX across 4 months for any of the groups. In contrast, there was considerable within-subject variation in osteocalcin and CTX concentrations. However, differences in values exhibited no discernible pattern, suggesting that within-subject variation can be reduced by averaging repeat measurements. In summary, the data provide reference values for male and female rhesus and cynomolgus macaques and support the utility of osteocalcin and CTX as biomarkers to monitor bone turnover at the population level.

Alternate JournalBone Rep
PubMed ID34541261
PubMed Central IDPMC8436065
Grant ListP51 OD011092 / OD / NIH HHS / United States