Diagnostic utility of osteocalcin, undercarboxylated osteocalcin, and alkaline phosphatase for osteoporosis in premenopausal and postmenopausal women

Abstract

Background: We aimed to investigate the diagnostic utility of osteocalcin (OC), undercarboxylated osteocalcin (ucOC), and alkaline phosphatase (ALP) in pre- and postmenopausal women for femoral neck, L1-4, and L2-4 bone mineral density (BMD) values by taking into consideration their age, body mass index (BMI), and menopausal status.

Methods: Premenopausal (N=40) and postmenopausal cases (N=42) were classified as 25-34 or 35-45 yr of age and within the first 5 yr or 5 yr or more after the onset of menopause, respectively.

Results: Among the groups, statistical differences were found for age, BMI, OC, ucOC, ALP, femoral neck BMD, L1-4 BMD, and L2-4 BMD. The highest serum OC, ucOC, and ALP levels were observed in cases within the first 5 yr after the onset of menopause, probably due to a more rapid bone turnover rate. The best predictors for the femoral neck osteoporosis were ALP, OC, and calcium (areas under the ROC curve [AUC]=0.882, 0.829, and 0.761, respectively), and those for L1-4 and L2-4 osteoporosis were OC, ALP, and ucOC (AUC=0.949, 0.873, and 0.845; and 0.866, 0.819, and 0.814, respectively). Multiple logistic regression analysis revealed that the most discriminative parameter for osteoporosis was OC.

Conclusions: These results indicate that serum OC levels, with or without ucOC and ALP, may be useful to monitor follow-up changes that currently cannot be assessed with BMD and to diagnose femoral neck, L1-4 spine, and L2-4 spine osteoporosis.

Keywords: Bone mineral density; Menopause; Osteocalcin; Osteoporosis; Undercarboxylated osteocalcin.

Fig. 1

Distribution of serum osteocalcin levels in 4 different groups of menopausal status. ^*, P=0.001 vs. the 35-45 yr age-group.

Fig. 2

Distribution of femoral neck, L1-4 spine, and L2-4 spine BMD values in 4 different groups of menopausal status. ^*, P=0.02 vs. the 25-34 yr age-group and P=0.002 vs. the 35-45 yr age-group; ^†, P=0.03 vs. the 25-34 yr age-group and P=0.006 vs. the 35-45 yr age-group; ^‡, P=0.014 vs. the 25-34 yr age-group and P=0.006 vs. the 35-45 yr age-group; ^§, P<0.001 vs. the 25-34 yr age-group and the 35-45 yr age-group; ^*†, P<0.001 vs. the 25-34 yr age-group and the 35-45 yr age-group.

Fig. 3

Distribution of serum osteocalcin levels in normal, osteopenia and osteoporosis groups. ^*, P=0.017 vs. the normal group; ^†, P=0.029 vs. the normal group; ^‡, P=0.001 vs. the normal group and P=0.011 vs. the osteopenia group; ^§, P<0.001 vs. the normal group and P=0.004 vs. the osteopenia group; ^*†, P<0.001 vs. the normal group and P=0.029 vs. the osteopenia group.

Fig. 4

ROC curve analysis of biochemical bone markers for osteoporosis. (A) femoral neck osteoporosis (AUC=0.882, P=0.002 for ALP; AUC=0.829, P=0.008 for OC; AUC=0.761, P=0.034 for calcium), (B) L1-4 spine osteoporosis (AUC=0.949, P=0.003 for OC; AUC=0.873, P=0.012 for ALP; AUC=0.845, P=0.021 for ucOC), and (C) L2-4 spine osteoporosis (AUC=0.866, P=0.003 for OC; AUC=0.819, P=0.010 for ALP; AUC=0.814, P=0.011 for ucOC). Abbreviations: AUC, area under the curve; ALP, alkaline phosphatase; OC, osteocalcin; ucOC, undercarboxylated osteocalcin.