Comparing the Effect of Short Term Post Meals and Bedtime Calcium Supplementation on the C-terminal Telopeptide Crosslinks and PTH Levels in Postmenopausal Osteopenic Women
Somlak Chuengsamarn, MD*, Sompongse Suwanwalaikorn, MD**
Affiliation : * Department of Medicine, Faculty of Medicine, Srinakharinwirot University ** Department of Medicine, Faculty of Medicine, Chulalongkorn University
Background : Calcium supplement for postmenopausal osteopenic women can significantly reduce bone loss
and the risk of fractures. However, the optimal time for calcium supplementation remains controversial.
Objective : The aim of the present study was to compare the effect of twice daily post meals and bedtime
calcium supplementation for a two week periods, on C-terminal telopeptide crosslinks and PTH levels in
postmenopausal osteopenic women.
Design : A randomized double blind placebo-control, crossover design, was carried out on 3 consecutive
periods 3 of a 2-week treatment regimen. In the first period, all the subjects randomly received either two
calcium carbonate tablets (Chalk Cap all subjects randomly received either two calcium 334 mg per tab)
or placebo at bedtime with one tablet of calcium tablet or placebo after breakfast and dinner for two weeks.
In the second period, subjects received only placebo tablets after the meals and at bedtime for 2 weeks. In the
third period subjects received either calcium carbonate or placebo for another two weeks. The C-terminal
telopeptide crosslinks were measured at 8.00 am and serum PTH were sampled at 8 time points (12.00 am,
2.00 am, 4.00 am, 6.00 am, 8.00 am, 9.00 am, 5.00 pm, and 7.00 pm respectively by the end of each study at
the first and third period.
Results : The present study showed thirty-six postmenopausal subjects (mean age 63.9 + 3.66 years)
participated in the present study. The mean T-score BMD of the spine and hip were -2.96 + 0.87 and -2.96 +
0.77 gm/cm2. C-terminal telopeptide crosslinks levels of the bedtime supplementation were significantly
lower than the post meal supplementation (0.228 + 0.002 ng/ml vs 0.313 + 0.003 ng/ml, p < 0.001). The
mean night time serum PTH level during the bedtime was significantly lower than the post meal period.
(25.17 + 2.31 pg/ml vs 31.930 + 2.677 pg/ml, p < 0.001). No differences in the post meal PTH level between
two periods were observed.
Conclusion : The bedtime calcium supplementation appeared to reduce the bone resorption marker and
night time serum PTH levels greater than the post meal calcium supplementation in this short term period
study. However, long term comparison may be needed.
Keywords : Parathyroid hormone, Bone marker, Osteopenic women, Calcium intake
