Clinical Trial: African-American Bone Metabolism and 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 African-American Women and Healthy Non-pregnant African-American Women
Brief Summary:
The primary aim of this study is to obtain measures of amino-terminal telopeptides of procollagen 1 (P1NP), a marker of bone formation, in lactating and non-lactating post-partum African-American women both at 6-8 and at 12-14 weeks post-partum, and to compare these values to those of normal controls. The secondary aim is to obtain at the same time points, measurements of Parathyroid Hormone-related Protein (PTHrP), additional markers of bone turnover [e.g. N-telopeptide of collagen cross-links (NTx), C-telopeptide of collagen cross-links (Ctx),bone specific alkaline phosphatase (BSAP) and osteocalcin (OC)], calcium and vitamin D metabolism in these subjects. These results will be compared with a non-African-American cohort of post-partum women and normal controls.
The investigators hypothesize that African-American lactating women will have increased bone turnover when compared to non-lactating postpartum women and normal controls. The investigators further hypothesize that bone turnover is increased in lactating women independent of race.
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 different 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. Parathyroid Hormone-related Protein (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 type 1 Procollagen N-terminal Propeptide (P1NP) in pregnancy or lactation.
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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 post-partum African-American women both at 6-8 and at 12-14 weeks post-partum and normal controls [ Time Frame: 4 months ]
Original Primary Outcome: Same as current
Current Secondary Outcome: Measurements of Parathyroid Hormone-related Protein (PTHrP), additional markers of bone turnover (i.e. NTX - N-telopepetide of collagen cross-links, CTX - C-telopepetide of collagen cross-links, BSAP - bone specific alkaline phosphatase and osteocalcin), [ Time Frame: 4 months ]
Original Secondary Outcome: Same as current
Information By: University of Pittsburgh
Dates:
Date Received: November 4, 2008
Date Started: January 2009
Date Completion:
Last Updated: October 30, 2013
Last Verified: October 2013
