Clinical Trial: Bone Metabolism and Parathyroid Hormone-related Protein (PTHrP) Lactation Study
Study Status: Completed
Recruit Status: Completed
Study Type: Observational
Official Title: A Prospective Cohort Pilot Study of Bone Metabolism in Lactating and Non-lactating Postpartum Women and Healthy Non-pregnant Women
Brief Summary: The primary aim of the study is to measure bone formation in both lactating and non-lactating post-partum women and compare these to those in healthy non-pregnant controls. The secondary aim is to obtain measurements of Parathyroid Hormone-related Protein (PTHrP), markers of bone resorption, and calcium and vitamin D metabolism in these subjects. The investigators believe that lactating women will have an increase in bone resorption but no increase in bone formation when compared to non-lactating post-partum women and normal controls.
Detailed Summary:
Pregnancy and lactation are both states of altered maternal calcium and bone metabolism which may have a significant impact on the development of peak bone mass. While these two states are characterized by different hormonal environments, both have been associated with significant bone loss. The maternal hormonal mechanism for providing calcium to meet the needs of the developing fetus appear to differ from those that meet the needs of lactation. During pregnancy, the 30 gm of calcium required by the fetus comes predominantly from an increase in maternal intestinal calcium absorption which is mediated by 1, 25 dihydroxy vitamin D and other factors. Several studies have measured total and free 1, 25 dihydroxy vitamin D through pregnancy and find the values nearly double. Serum Parathyroid Hormone (PTH) levels fall to about 10-30% of the mean non-pregnant value in the first trimester and then increase to the mid-normal range by term, while ionized calcium remains normal throughout pregnancy. PTHrP levels gradually increase throughout pregnancy although the source (maternal, fetal, or placental) remains unclear. Most studies of bone metabolism in humans during pregnancy have measured changes in markers of bone turnover rather than bone density to avoid radiation exposure to the fetus. These studies have been confounded by several variables such as the effects of hemodilution in pregnancy, altered glomerular filtration rates (GFR), degradation, and clearance of markers by the placenta, which may cloud the results. Some of these studies report an increase in urinary markers of bone resorption from early to mid pregnancy while bone formation markers decrease and then rise before term. Importantly, no one has assessed state-of-the-art markers of bone formation such as P1NP in pregnancy or lactation.
During lactation in humans, it is estimated that 600 to 1000 ml of milk are prod
Sponsor: University of Pittsburgh
Current Primary Outcome: Measurements of amino-terminal telopeptides of procollagen 1 (P1NP), a marker of bone formation, in lactating and non-lactating postpartum women both at 6-8 and at 12-14 weeks post-partum, and to compare these values to those of normal controls [ Time Frame: 4 months ]
Original Primary Outcome:
Current Secondary Outcome: Measurements of Parathyroid Hormone-related Protein (PTHrP), markers of bone turnover, calcium and vitamin D metabolism [ Time Frame: 4 months ]
Original Secondary Outcome:
Information By: University of Pittsburgh
Dates:
Date Received: January 31, 2007
Date Started: January 2007
Date Completion:
Last Updated: October 30, 2013
Last Verified: October 2013
