The purpose of the study is to determine the best dose of Vitamin D to give to hip fracture patients to achieve the optimal therapeutic level.

Low Vitamin D levels can cause faster bone loss and increase the risk of having a fracture. Patients who experience a hip fracture have low levels of Vitamin D. It is not clear how much Vitamin D must be taken in order to reach this optimal level.

Serum 25-hydroxyvitamin D3 (25-OHD) concentrations are the recognized functional status indicator for vitamin D. Although there is no clear consensus, vitamin D 'insufficiency' has been considered in the range of 25- 75/80 nmol/L. Patients with acute hip fracture are at high risk for a recurrent hip fracture or other fragility fractures (and falls) and are a group who should be targeted for osteoporosis treatment (i.e. Bisphosphonate or other antiresorptive). Before fracture patients start on a bisphosphonate, however, an important consideration is whether 25-OHD levels are at a therapeutic level (>75 nmol/l and less than 150-200 nmol/L). Case-control studies indicate that older people who experience a hip fracture have lower serum concentrations of 25-OHD than do those without a fracture. In cross-sectional studies, the majority of patients with hip fracture are considered to have insufficient vitamin D levels. Although the benefits of supplementing patients with at least 800 to 1000 IU/day Vitamin D3 may be recognized, there is little information available to guide physicians regarding the appropriate management of hip fracture patients who may be severely Vitamin D deficient, particularly in acute hip fracture patients. Few studies have examined whether high dose vitamin D (i.e. 50,000 IU or greater/week) offers an advantage over smaller, routinely prescribed doses (i.e. 800 or 1000 IU), particularly in hip fracture patients.

The purpose of this study is to determine the number of hip fracture patients reaching an optimal level of vitamin D comparing between three different Vitamin D dose strategies:

A. 50,000 D2 oral bolus followed by 800 IU D3 daily B. 100,000 D2 oral bolus followed by 800 IU D3 daily C. 800 IU D3 daily

The Vitamin D strategies will be administered over 3-months in acute hip fracture patients. The proportion of patients reaching an optimal level of 25-OHD (>75 nmol/L) will be determined.

Secondary measures include the Timed Up and Go test, and 2 Minute Walk Test to compare the effects of the Vitamin D supplementation strategies on functional and muscle strength scales.

Inclusion Criteria:

• Fragility hip fracture patient
• Previous Vitamin D supplementation is okay.

Exclusion Criteria:

• Patients with pathological fracture secondary to malignancy or intrinsic bone disease (eg. Paget's disease)
• Cancer in the past 10 years likely to metastasize to bone
• Renal insufficiency (creatinine <30 mls/min)
• Hypercalcemia (primary hyperparathyroidism; granulomatous diseases; drug-induced such as lithium, thiazides), hypocalcemia, hypercalciuria, fracture or stroke within the last 3 months
• Hormone replacement therapy, calcitonin, fluoride, or bisphosphonates during the previous 24 months
• Pre-existing bone abnormality
• Renal stones in past 10 years