Cholecalciferol in elderly with osteoarthritis of the hip.

Rationale:
Vitamin D insufficiency and deficiency are becoming a worldwide problem. It is associated with increased risk of falling, osteoporosis and increased risk of fractures. Elderly are more at risk for vitamin D insufficiency and deficiency. Several strategies for vitamin D suppletion are used, however a high loading dose is hardly used.

Objective:
To study the effect of high dose oral cholecalciferol suppletion on serum 25-OHD in elderly with coxarthrosis.

Study design:
A randomised double-blinded controlled clinical trial.

Study population:
Patients with coxarthrosis aged 70 years and older.

Intervention (if applicable):
Two groups of patients will be formed, one group of patients being treated conservative, one group of patients who will be operated. Within both groups the patients will be randomised between getting a single oral dose of either 150,000 IU or 300,000 IU cholecalciferol.

Main study parameters/endpoints:
The effect of different doses cholecalciferol on serum 25-OHD.

Nature and extent of the burden and risks associated with participation, benefit and group relatedness:

A high loading dose is a potent way of raising serum 25-OHD. In theory, there is a risk of vitamin D toxicity. Extra blood test form an additional burden as well as extra visits to the clinic.

It is hypothesised that a loading dose of 150,000 IU cholecalciferol and of 300,000 IU are both effective in normalizing serum 25-OHD in insufficient en deficient individuals, but also in elevating serum 25-OHD in elderly with sufficient serum 25-OHD without toxicity, meaning that the lowest of both doses is preferred. It is not expected that elective hip surgery will influence cholecalciferol uptake.

On day 3, 5, 14 and after 6 weeks and 3 months.

150,000 or 300,000 IU cholecalciferol.