Undercarboxylated Osteocalcin and Its Associations With Bone Mineral Density, Bone Turnover Markers, and Prevalence of Osteopenia and Osteoporosis in Chinese Population: A Cross-Sectional Study

Abstract

ObjectiveUndercarboxylated osteocalcin (ucOC) is one form of osteocalcin lacking full carboxylation, which plays an important role in bone homeostasis, glucose homeostasis, and energy metabolism. Our aim is to obtain the profile of serum ucOC level according to gender and age and explore its associations with bone mineral density (BMD), bone turnover markers (BTMs), and prevalence of osteopenia and osteoporosis in the Chinese population.MethodsThis is a cross-sectional study with 900 subjects, composed of 431 men and 469 women. Clinical information was collected, and BMD values of the lumbar spine (L1–4), left femoral neck, and total hip were scanned. Biochemical markers including hepatic and renal function, serum calcium, serum phosphorus, procollagen type 1 N-propeptide (P1NP) β-CrossLaps of type I collagen-containing cross-linked C-telopeptide (β-CTX) intact parathyroid hormone (PTH), 25-hydroxyvitamin D (25OHD), and ucOC were measured.ResultsWe found that the median ucOC level was higher in men than women [men, 2.6 ng/ml; women, 1.6 ng/ml; p < 0.001]. The profile according to age showed that ucOC levels were the lowest at the age of 40–49 years in both men [2.55 ng/ml (95% CI = 1.96–3.13 ng/ml)] and women [1.57 ng/ml (95% CI = 1.12–2.03 ng/ml)]; in patients younger than 49 years, they decreased with age; then over 50 years, they quickly increased. Furthermore, we found that a higher ucOC level was correlated with lower BMD values at the lumbar spine (men, r = −0.128, p = 0.013; women, r = −0.321, p < 0.001), femoral neck (men, r = −0.095, p = 0.062; women, r = −0.260, p < 0.001), and total hip (men, r = −0.123, p = 0.015; women, r = −0.209, p < 0.001) and higher P1NP (men, r = 0.307, p < 0.001; women, r = 0.239, p < 0.001) and β-CTX (men, r = 0.169, p = 0.001; women, r = 0.354, p < 0.001) levels in both men and women. Furthermore, we also showed that a 1 − SD increase in ucOC was associated with an odds ratio (OR) of 1.63 and 1.70 for having osteopenia or osteoporosis in men and women, respectively (men, 95% CI = 1.25–2.13, p = 0.004; women, 95% CI = 1.19–2.42, p = 0.004).ConclusionsWe first revealed the profile of serum ucOC levels according to gender and age in the Chinese population and demonstrated the associations of ucOC with BMD and BTMs and the risk of prevalent osteopenia or osteoporosis. Our findings provide a clue to elucidate the function of ucOC in bone metabolism.

Causal association of NAFLD with osteoporosis, fracture and falling risk: a bidirectional Mendelian randomization study

“…In a recent study by Xu et al. ( 31 ), decreased OCN was associated with bone turn markers and osteopenia, and osteoporosis. Thus, decreased OCN in NAFLD patients could be a potential factor leading to osteoporosis.…”

Clinical significance of zoledronic acid in combination with calcium tablets and calcitriol for hip biomechanics and bone mineral density after total hip replacement: a prospective randomized controlled trial

“…The de ciency of 25 hydroxyvitamin D will lead to the decrease of serum calcium, and then lead to osteoporosis [18,19]. P1NP and osteocalcin are indicators re ecting the ability of OCN, and when their levels increase, the body's osteogenic activity is more active [20][21][22][23]. β-CTX is an indicator of the activity of human osteoclasts, and its clinical signi cance is to show the degree of osteoclast absorption of bone.…”

Additional Insights Into the Role of Osteocalcin in Osteoblast Differentiation and in the Early Steps of Developing Alveolar Process of Rat Molars

“…21,46,47 Although it is not yet known whether the inhibitory action of OCN on the bone matrix mineralization is attributed to its carboxylated or undercarboxylated form, a recent clinical study has shown a correlation between increased serum levels of undercarboxylated OCN and a reduction in bone mineral density, both in men and in women. 48 Therefore, the exact role of OCN during bone matrix mineralization remains controversial. Nevertheless, the results of our study support the idea that carboxylated OCN stimulates bone matrix mineralization, at least during the earliest stages of alveolar process formation in rat maxillae.…”