A meta-analysis of serum osteocalcin level in postmenopausal osteoporotic women compared to controls

Zhongyu Liu,Lei He,Yang Yang,Chunxiao Luo,Yutong Jiang,Jianwen Dong,Limin Rong,Ruiqiang Chen

doi:10.1186/s12891-019-2863-y

Abstract

BackgroundCirculatory osteocalcin (OC) has been widely used as a biomarker to indicate bone turnover status in postmenopausal osteoporosis (PMO). However, the change of serum OC (sOC) level in PMO cases compared to postmenopausal controls remains controversial.MethodsWe searched the online database of PubMed and Cochrane Library. A meta-analysis of case-control studies was performed to compare the pooled sOC level between PMO patients and postmenopausal controls. Subgroup analysis according to potential confounding factors (different OC molecules and regions of the study population) was also performed.ResultsTen case-control studies with 1577 postmenopausal women were included in this meta analysis. We found no significant difference in the pooled sOC level [mean difference (MD) = 1.84, 95% confidence interval (CI): (− 1.49, 5.16), p = 0.28] between PMO patients and controls. Subgroup analysis also revealed no significant difference in intact OC [MD = 1.76, 95%CI: (− 1.71, 5.23), p = 0.32] or N-terminal mid-fragment of the OC molecule [MD = 0.67, 95%(− 5.83, 7.18), p = 0.84] between groups. For different regions, no significant difference in sOC was found in Asian population between cases and controls [MD = -0.06, 95%(− 6.02, 5.89), p = 0.98], while the pooled sOC level was significantly higher in European PMO cases than controls [MD = 3.15, 95%(0.90, 5.39), p = 0.006].ConclusionsOur analysis revealed no significant difference in sOC level between PMO cases and controls according to all the current eligible studies. OC molecules are quite heterogeneous in the circulation and can be influenced by glucose metabolism. Therefore, sOC is currently not a good indicator for the high bone turnover status in PMO. More trials with standardized methodologies for the evaluation of circulatory OC are awaited to update our current findings.

Highlights

Circulatory osteocalcin (OC) has been widely used as a biomarker to indicate bone turnover status in postmenopausal osteoporosis (PMO)
Osteocalcin (OC), known as the bone Gla protein (BGP), is a 5.8 kDa, hydroxyapatite-binding protein that could be synthesized by osteoblasts, odontoblasts and hypertrophic chondrocytes [4] and is the most abundant non-collagenous protein found in bone matrix
Circulatory OC may come from both bone formation and bone resorption [5, 6] and serum osteocalcin level may theoretically increase in PMO, which is characterized by high bone turnover status with both increased bone formation and bone resorption

Summary

Introduction

Circulatory osteocalcin (OC) has been widely used as a biomarker to indicate bone turnover status in postmenopausal osteoporosis (PMO). The change of serum OC (sOC) level in PMO cases compared to postmenopausal controls remains controversial. Osteoporosis (OP) is a systemic skeletal disorder characterized by low bone mass and deteriorated microarchitecture of bone tissue. PMO may lead to fragility fracture and is one of the most disabling consequences of postmenopausal women. Osteocalcin (OC), known as the bone Gla protein (BGP), is a 5.8 kDa, hydroxyapatite-binding protein that could be synthesized by osteoblasts, odontoblasts and hypertrophic chondrocytes [4] and is the most abundant non-collagenous protein found in bone matrix. Circulatory OC may come from both bone formation and bone resorption [5, 6] and serum osteocalcin (sOC) level may theoretically increase in PMO, which is characterized by high bone turnover status with both increased bone formation and bone resorption

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Discussion

Conclusion