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We assessed the potential of Calcium (Ca) isotope fractionation measurements in blood (δ 44/42 Ca Blood ) and urine (δ 44/42 Ca Urine ) as a new biomarker for the diagnosis of osteoporosis. One hundred post-menopausal women aged 50 to 75 years underwent dual-energy X-ray absorptiometry (DXA), the gold standard for determination of bone mineral density. After exclusion of women with kidney failure and vitamin D deficiency (<25 nmol/l) 80 women remained in the study. Of these women 14 fulfilled the standard diagnostic criteria for osteoporosis based on DXA. Both the δ 44/42 Ca Blood ( p < 0.001) and δ 44/42 Ca Urine ( p = 0.004) values were significantly different in women with osteoporosis (δ 44/42 Ca Blood : −0.99 ± 0.10‰, δ 44/42 Ca Urine : +0.10 ± 0.21‰, (Mean ± one standard deviation (SD), n = 14)) from those without osteoporosis (δ 44/42 Ca Blood : −0.84 ± 0.14‰, δ 44/42 Ca Urine : +0.35 ± 0.33‰, (SD), n = 66). This corresponded to the average Ca concentrations in morning spot urine samples ([Ca] Urine ) which were higher ( p = 0.041) in those women suffering from osteoporosis ([Ca] Urine-Osteoporosis : 2.58 ± 1.26 mmol/l, (SD), n = 14) than in the control group ([Ca] Urine - Control : 1.96 ± 1.39 mmol/l, (SD), n = 66). However, blood Ca concentrations ([Ca] Blood ) were statistically indistinguishable between groups ([Ca] Blood , control: 2.39 ± 0.10 mmol/l (SD), n = 66); osteoporosis group: 2.43 ± 0.10 mmol/l (SD, n = 14) and were also not correlated to their corresponding Ca isotope compositions. The δ 44/42 Ca Blood and δ 44/42 Ca Urine values correlated significantly ( p = 0.004 to p = 0.031) with their corresponding DXA data indicating that both Ca isotope ratios are biomarkers for osteoporosis. Furthermore, Ca isotope ratios were significantly correlated to other clinical parameters ([Ca] Urine , ([Ca] Urine/ Creatinine)) and biomarkers (CRP, CTX/P1NP) associated with bone mineralization and demineralization. From regression analysis it can be shown that the δ 44/42 Ca Blood values are the best biomarker for osteoporosis and that no other clinical parameters need to be ta...

The potential relationship between daily physical activity and pregnancy outcome remains unclear because of the wide variation in study designs and physical activity assessment measures. We sought to prospectively quantify the potential effects of the various domains of physical activity on selected birth outcomes in a large unselected population. The sample consisted of 11,759 singleton pregnancies from the Avon longitudinal study of parents and children, United Kingdom. Information on daily physical activity was collected by postal questionnaire for self-report measures. Main outcome measures were birth weight, gestational age at delivery, preterm birth and survival. After controlling for confounders, a sedentary lifestyle and paid work during the second trimester of pregnancy were found to be associated with a lower birth weight, while ‘bending and stooping’ and ‘working night shifts’ were associated with a higher birth weight. There was no association between physical exertion and duration of gestation or survival. Repetitive boring tasks during the first trimester was weakly associated with an increased risk of preterm birth (<37 weeks) (adjusted odds ratio [OR] = 1.25, 95% CI 1.04–1.50). ‘Bending and stooping’ during the third trimester was associated with a reduced risk of preterm birth (adjusted OR = 0.73, 95% CI 0.63–0.84). Demanding physical activities do not have a harmful effect on the selected birth outcomes while a sedentary lifestyle is associated with a lower birth weight. In the absence of either medical or obstetric complications, pregnant women may safely continue their normal daily physical activities should they wish to do so.