Longitudinal Lactation Bone Density Study

Completed

Conditions studied: Lactation, Other Disorders of Bone Density and Structure, Endocrine; Complications

In brief

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).

Key facts

Study ID

NCT01630629

Run by

University of Pittsburgh

People needed

77

Starts

2012-08-01

Expected to finish

2015-09-01

Last updated by the study team

2016-06-16

Who can join

Age: 21 and older, up to 45. Sex: female. Healthy volunteers: accepted.

You may qualify if…

• 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

You may not qualify if…

• 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

Where it is running

• University of Pittsburgh Medical Center — Pittsburgh, Pennsylvania, United States

Full record on ClinicalTrials.gov

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