None listed
Conditions
Brief summary
The objective of this study is to determine whether calcium supplements acutely influence blood pressure and blood coagulation. This is a randomised, double-blind, placebo-controlled, cross-over trial. Participants will be 40 healthy postmenopausal women. Participants will attend two visits at our research clinic where they will receive 1 g of calcium as citrate or a placebo containing no calcium. Visits will be separated by at least 6 days. Blood will be sampled and blood pressure measured prior to, and 2, 4 and 6 hours after each intervention is ingested. Blood coagulation will be measured at each time-point by thromboelastography.
Interventions
A single dose of 1 g of calcium as citrate as an oral tablet. There will be a 6 day wash out period between interventions.
Sponsors
University of Auckland
Study design
Allocation
Randomised controlled trial
Intervention model
Crossover
Primary purpose
Prevention
Masking
Blinded (masking used) (Subject, Caregiver, Investigator, Outcomes Assessor)
Eligibility
Sex/Gender
All
Age
0 to No maximum
Healthy volunteers
Yes
Inclusion criteria
Female, postmenopausal 5 years or more (menopause defined as at least 12 months since last period in a woman aged > 45 yrs with intact uterus, or serum oestradiol < 100 pmol/l with FSH > 50 IU/l in younger or hysterectomised women).
Exclusion criteria
Current smoker, current use of Warfarin, aspirin or other blood thinning medications, diabetes, current use of blood pressure medication, past history of coronary heart disease, cerebrovascular disease or peripheral vascular disease, renal impairment (serum creatinine >0.15 mmol/L), chronic liver disease, untreated hypothyroidism or hyperthyroidism, concurrent major systemic illness, including malignancy, active major gastrointestinal disease, metabolic bone diseases, or serum ALP >normal, primary hyperparathyroidism, calcium supplements: those consistently using 500 mg/day or more need to be off calcium supplements for 6 months before entering the study; doses <100 mg/day can be continued during the study; doses between 100 and 499 mg/day require intermediate times of withdrawal prior to study entry, current or expected use of oral glucocorticoid drugs during the trial period, current or past use of bisphosphonate therapy in the preceding 2 years, use of hormone replacement therapy within the last 12 months, use of other medication known to cause osteoporosis or interfere with bone metabolism, calciferol supplements > 2000 IU/day (lower doses can be continued during the study).
Outcome results
None listed