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Longitudinal Lactation Bone Density Study

The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been evaluated by the U.S. Federal Government. Read our disclaimer for details. Identifier: NCT01630629
Recruitment Status : Completed
First Posted : June 28, 2012
Last Update Posted : June 16, 2016
Information provided by (Responsible Party):
Mara Horwitz, University of Pittsburgh

Brief Summary:

Changes in maternal calcium metabolism are necessary during lactation to provide adequate calcium in breast milk for development of the newborn skeleton. The calcium in milk is derived from the maternal skeleton, resulting in significant bone loss, a process thought to be mediated by the actions of parathyroid hormone-related protein (PTHrP) in combination with a decreased estrogen levels. After weaning, bone lost during lactation is rapidly regained.

Differences between African-American and Caucasian bone metabolism are well documented and include higher bone mineral density (BMD), lower risk of fragility fracture, lower 25-hydroxyvitamin D (25(OH) D), and higher PTH in African-Americans compared to Caucasians. Most studies of bone metabolism in lactating women have been done in Caucasians. Because of differences in bone metabolism between African-Americans and Caucasians, we do not know whether African-Americans will have similar findings.

The primary aim of this study is to compare the changes in bone mineral density (BMD) during lactation in African-Americans with those in Caucasians. It is not known whether the loss in BMD during lactation will be the same for both races. African-Americans display skeletal resistance to PTH with short-term infusions and have lower bone resorption, higher BMD and lower fracture risk than Caucasians. A recent study by our group indicated that lactating African-American mothers had slightly lower bone resorption but quantitatively similar bone formation compared to Caucasians. However, there was a significant increase of 2-3 fold in markers of bone formation and resorption in both groups. Therefore, it is currently not known whether the loss in BMD during lactation will be the same for both races. Primary outcome measures in this study will include spine, hip and radius BMD by Dual X-Ray Absorbiometry (DXA)Scans during lactation (at 2,12 and 24 weeks postpartum or at weaning if prior to 24 weeks postpartum, and six months after weaning (+1 week). This longitudinal protocol will distinguish between two hypotheses. Either: a) as measured by BMD, bone loss in African-Americans during lactation will be equal to that in Caucasians, and skeletal recovery will be the same or possibly accelerated compared to Caucasians; or, b) African-Americans will be resistant to bone loss during lactation compared to Caucasians because of resistance to Parathyroid Hormone-related Protein (PTHrP).

Condition or disease
Lactation Other Disorders of Bone Density and Structure Endocrine; Complications

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Study Type : Observational
Actual Enrollment : 77 participants
Observational Model: Cohort
Time Perspective: Prospective
Official Title: "Bone Density and Calcitropic Hormones During Lactation in African-American and Caucasian Women"
Study Start Date : August 2012
Actual Primary Completion Date : September 2015
Actual Study Completion Date : September 2015

Resource links provided by the National Library of Medicine

African-American Lactating Women
Healthy African-American women who are exclusively breast-feeding.
Caucasian Lactating Women
Healthy Caucasian women who are exclusively breast-feeding.

Primary Outcome Measures :
  1. Change from baseline in bone density measurements (BMD) [ Time Frame: Change from baseline in BMD at 2,12, 24 weeks postpartum, and six months after weaning. ]
    Primary outcome measures will include spine, hip and radius BMD by DXA at 2, 12, and 24 weeks post-partum and 6 months post-weaning.

Secondary Outcome Measures :
  1. Change from baseline of bone metabolism measurements [ Time Frame: Change from baseline at 2, 12,and 24 weeks postpartum, and six months after weaning. ]
    Bone metabolism measurements include: markers of bone turnover including calcium metabolic parameters such as calcium, phosphorus, fractional excretion of calcium, PTH(1-84), PTHrP, vitamin D metabolites, estradiol, sex hormone binding globulin (SHBG), prolactin, and breast milk calcium levels.

Biospecimen Retention:   Samples Without DNA
Blood and breast milk

Information from the National Library of Medicine

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Ages Eligible for Study:   21 Years to 45 Years   (Adult)
Sexes Eligible for Study:   Female
Accepts Healthy Volunteers:   Yes
Sampling Method:   Non-Probability Sample
Study Population
New mothers will be recruited from UPMC hospital population, primarily Magee Womens Hospital. As this is a study which aims to describe racial differences in bone metabolism during lactation in African-Americans and Caucasians, subjects must identify themselves as belonging to one of these groups.

Inclusion Criteria:

  • 21-45 years old
  • Post-partum after a singleton pregnancy
  • Exclusively breast-feeding (not more than one supplemental bottle of formula per day)
  • African-American or Caucasian by self-identification

Exclusion Criteria:

  • Subjects with cardiac, hypertensive, vascular, renal (serum creatinine of >1.5), pulmonary, endocrine, musculoskeletal, hepatic, hematologic, malignant or rheumatologic disease
  • Fractures or bone surgery within the past 12 months
  • Smokers and subjects with history of significant alcohol or drug use
  • Pregnant women
  • Women who achieved pregnancies with IVF or other hormonal manipulation
  • Women who had significant complications with the most recent pregnancy or who are unable to exclusively breastfeed beginning at birth
  • Subjects on chronic medications other than
  • stable doses of thyroid hormone
  • oral contraceptives
  • vitamin supplements
  • Women on Depo-Provera will be excluded
  • Receiving an investigational drug within 90 days
  • Weight greater than 130 kg
  • Z-score -3.0 or less (hip or spine) on initial DXA

Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its identifier (NCT number): NCT01630629

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United States, Pennsylvania
University of Pittsburgh Medical Center
Pittsburgh, Pennsylvania, United States, 15213
Sponsors and Collaborators
University of Pittsburgh
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Principal Investigator: Mara Horwitz University of Pittsburgh
Additional Information:

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Responsible Party: Mara Horwitz, Associate Professor of Medicine, University of Pittsburgh Identifier: NCT01630629    
Other Study ID Numbers: PRO12050600
First Posted: June 28, 2012    Key Record Dates
Last Update Posted: June 16, 2016
Last Verified: June 2016
Individual Participant Data (IPD) Sharing Statement:
Plan to Share IPD: No
Keywords provided by Mara Horwitz, University of Pittsburgh:
Bone Density
Physiological Properties
Bone Metabolism
Additional relevant MeSH terms:
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Bone Diseases
Musculoskeletal Diseases