Change in free vitamin D after high dose cholecalciferol
Research type
Research Study
Full title
Change in free vitamin D after high dose cholecalciferol administered to vitamin D deficient postmenopausal women.
IRAS ID
182140
Contact name
Aimee Card
Contact email
Sponsor organisation
Sheffield Teaching Hospitals NHS Trust
Duration of Study in the UK
2 years, 0 months, 1 days
Research summary
Vitamin D is essential for absorption of dietary calcium and bone mineralisation. Vitamin D deficiency is very prevalent in the UK- about 50% of people are below the recommended level.
The most commonly used measure of vitamin D status is 25(OH)D in blood. However, this measurement is affected by body weight, blood protein levels and inflammation and it may not truly reflect vitamin D status. More than 99% of total 25(OH)D in the blood is bound to carrier proteins and relatively inactive. Less than 1% of 25(OH)D is ‘free’ (not protein-bound) and is able to enter cells and carry out its function. We think that free 25(OH)D may be a better indicator of vitamin D status than total 25(OH)D.
We need to understand how free 25(OH)D responds to vitamin D treatment so that we can give better advice to patients and doctors about treating vitamin D deficiency. It is common practice to give a single high dose of vitamin D treatment, to avoid the need for people to take regular tablets. However, in one previous study, this approach was associated with an increase in falls. Our hypothesis is that giving a single high dose might overwhelm the carrier proteins and cause a large rise in the free, active 25(OH)D which could cause blood calcium levels to rise above normal.
We will give three different one-off doses of vitamin D (50,000 units, 150,000 units and 500,000 units) to 84 vitamin D deficient (<30nmol/l) postmenopausal women, and follow them up for three months to study changes in total and free 25(OH)D, calcium and clinical response. This will allow us to determine how free and total 25(OH)D change after the different doses of vitamin D and whether there is an excess rise in free 25(OH)D with higher doses.REC name
East Midlands - Nottingham 1 Research Ethics Committee
REC reference
15/EM/0345
Date of REC Opinion
26 Aug 2015
REC opinion
Favourable Opinion