The Journal of Clinical Endocrinology & Metabolism November 1, 2013 vol. 98 no. 11 E1702-E1709
John F. Aloia,
Shahidul Islam and
James K. Yeh
Winthrop University Hospital, Bone Mineral Research Center, Mineola, New York 11501
Address all correspondence and requests for reprints to: John F. Aloia, MD, Winthrop University Hospital, 222 Station Plaza North, Suite 510, Mineola, New York 11501. E-mail: jaloia at winthrop.org.
Context: Bone health is influenced by the intake of both calcium and vitamin D.
Objective: Our objective was to evaluate the influence of calcium and vitamin D supplementation on PTH and bone turnover.
Setting, Patients, and Design: At an ambulatory research center, 159 postmenopausal healthy white women participated in this double-blind, placebo-controlled parallel, longitudinal factorial study that was 6 months in duration.
Interventions: Subjects were randomly allocated to 4 groups:
- 1) double placebo,
- 2) calcium (1200 mg daily) plus placebo,
- 3) vitamin D3 (100 μg) plus placebo, and
- 4) vitamin D3 and calcium.
Serum and urine were collected fasting and 2 hours after a calcium load at baseline and at 3 and 6 months.
Main Outcome Measures: Serum PTH, cross-linked C-telopeptide (CTX), and procollagen type I N-terminal propeptide (P1NP) were measured.
Results: Before study medication, a calcium load resulted in a decline in PTH and CTX and an increase in urinary calcium excretion. Serum CTX and P1NP declined over time with calcium supplementation but did not change with increased vitamin D intake. There was a decline in PTH in the vitamin D groups in the fasting state compared with placebo. Suppression of PTH was greater after a calcium load in the vitamin D groups. A calcium load decreased PTH and CTX and raised urinary calcium.
Conclusions: Fasting PTH declines with vitamin D supplementation. PTH declines after calcium intake. Supplementation of the diet with 1200 mg calcium/d reduces bone turnover markers, whereas supplementation with up to 100 μg vitamin D3/d does not.
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