Reference intervals of biochemical bone turnover markers for Saudi Arabian women: a cross-sectional study

Independent predictors of all osteoporosis-related fractures among healthy Saudi postmenopausal women: the CEOR Study

This study was designed to identify independent predictors of all osteoporosis-related fractures (ORFs) among healthy Saudi postmenopausal women. We prospectively followed a cohort of 707 healthy postmenopausal women (mean age, 61.3±7.2 years) for 5.2±1.3 years. Data were collected on demographic characteristics, medical history, personal and family history of fractures, lifestyle factors, daily calcium intake, vitamin D supplementation, and physical activity score. Anthropometric parameters, total fractures (30.01 per 1000 women/year), special physical performance tests, bone turnover markers, hormone levels, and bone mineral density (BMD) measurements were performed. The final model consisted of seven independent predictors of ORFs: [lowest quartile (Q(1)) vs highest quartile (Q(4))] physical activity score (Q(1) vs Q(4): ≤12.61 vs ≥15.38); relative risk estimate [RR], 2.87; (95% confidence interval [CI]: 1.88-4.38); age≥60 years vs age<60 years (RR=2.43; 95% CI: 1.49-3.95); hand grip strength (Q(1) vs Q(4): ≤13.88 vs ≥17.28 kg) (RR=1.88; 95% CI: 1.15-3.05); BMD total hip (Q(1) vs Q(4): ≤0.784 vs 0.973 g/cm(2)) (RR=1.86; 95% CI: 1.26-2.75); dietary calcium intake (Q(1) vs Q(4): ≤391 vs ≥648 mg/day) (RR=1.66; 95% CI: 1.08-2.53); serum 25(OH)D (Q(1) vs Q(4): ≤17.9 vs ≥45.1 nmol/L) (RR=1.63; 95% CI: 1.06-2.51); and past year history of falls (RR=1.61; 95% CI: 1.06-2.48). Compared with having none (41.9% of women), having three or more clinical risk factors (4.8% of women) increased fracture risk by more than 4-fold, independent of BMD. Having three or more risk factors and being in the lowest tertile of T-score of [total hip/lumbar spine (L1-L4)] was associated with a 14.2-fold greater risk than having no risk factors and being in the highest T-score tertile. Several clinical risk factors were independently associated with all ORFs in healthy Saudi postmenopausal women. The combination of multiple clinical risk factors and low BMD is a very powerful indicator of fracture risk.

High prevalence of vitamin D deficiency among healthy Saudi Arabian men: relationship to bone mineral density, parathyroid hormone, bone turnover markers, and lifestyle factors

SUMMARY

In this cross-sectional study, the prevalence of vitamin D deficiency [serum 25-hydroxyvitamin D (25(OH)D) <50 nmol/L] was 87.8% among Saudi Arabian men. There was a linear inverse relationship between serum 25(OH)D and intact parathyroid hormone (PTH) levels, but without a threshold of 25(OH)D at which intact PTH values plateaued.

INTRODUCTION

Vitamin D insufficiency and/or deficiency has now reached epidemic proportions and has been linked to low bone mineral density (BMD), some lifestyle factors, and obesity in adults. This relationship is not well documented in Saudi Arabian men. This study examines the relationship between vitamin D status, intact parathyroid hormone (intact PTH), and lifestyle factors among Saudi Arabian men.

METHODS

This cross-sectional study involved 834 men aged 20-74 years living in Jeddah area who were randomly selected and medically examined. Men had their BMD (lumbar spine (L1-L4) and neck femur), 25(OH)D, intact PTH, and other parameters measured according to detailed inclusion criteria.

RESULTS

Deficiency (25(OH)D<50 nmol/L) and insufficiency (≥50-75 nmol/L) were present in 87.8% and 9.7%, respectively. Deficiency was common among older and obese men with no education and sedentary lifestyle sampled during summer and spring. Serum 25(OH)D showed an inverse linear relationship with intact PTH, but there was no threshold of serum 25(OH)D at which PTH levels plateaued. There was a positive correlation between BMD values at both lumbar spine (L1-L4) (P < 0.023) and neck femur (P < 0.036) and serum 25(OH)D levels, respectively.

CONCLUSIONS

Functionally significant vitamin D deficiency affects BMD and bone turnover markers among Saudi Arabian men and is largely attributed to older age, obesity, sedentary lifestyle, no education, poor exposure to sunlight, smoking, and poor dietary vitamin D supplementation. The data suggest that an increase in PTH cannot be used as a marker for vitamin D deficiency.

Determinants of serum sclerostin in healthy pre- and postmenopausal women

Sclerostin is a secreted Wnt antagonist produced almost exclusively by osteocytes that regulates bone mass. However, there is currently limited information on the determinants of sclerostin in a large population-based study. The main objectives of the present study were to: (1) establish reference normative interval values for serum sclerostin in randomly selected healthy premenopausal women; (2) study the changes in serum sclerostin in relation to age in premenopausal and postmenopausal women and the factors that may influence bone turnover; and (3) determine the effect of menopausal status on serum sclerostin. A total of 1803 women were studied (including [n = 1235] premenopausal, and [n = 568] postmenopausal women, respectively, aged 20 to 79 years). A total of 443 healthy premenopausal women (aged 35 to 45 years) were used to establish reference normative intervals for serum sclerostin. All women studied were medically examined and had their bone mineral density values obtained for the lumbar spine (L(1) -L(4) ) and femoral neck according to a detailed inclusion criteria. In all women, values of serum sclerostin increased with increasing age up to the age of 45 years, and remained increased in postmenopausal women. Significant increases were evident in serum sclerostin in postmenopausal women with increasing years since menopause. Using stepwise multiple linear regression analysis, several variables were identified as determinants of serum sclerostin, including age, parathyroid hormone, estradiol (E(2)), and follicle-stimulating hormone (FSH) for premenopausal women; age, FSH, and E(2) for postmenopausal women; and age, serum osteocalcin, FSH, and E(2) in the entire sample studied. Further studies are needed to establish the potential role of this increase in mediating the known age-related impairment in bone formation.