Individuals with spinal cord injury sustain significant loss of bone mass in their lower extremities (20-40% or more). This study evaluates the ability of PTH and weight-bearing, two interventions that build bone, to increase bone mass in this population.

This pilot project aims to evaluate PTH with weight-bearing in a group of individuals with chronic SCI and loss of bone mass in their lower extremities. A convenience sample of 12 people with SCI will be enrolled into a 6 month study assessing the effects of a weight-bearing regime plus daily PTH (Forteo 20ug sc) on BMD and bone markers. Subjects will be evaluated at 3 and 6 months after initiating treatment with measurement of bone density as well as bone markers of formation and resorption. An optional extension to 12 months will be offered to all subjects.

Inclusion Criteria:

1. Age 18-75 years
2. Complete SCI - total loss of motor function below level of lesion
3. Capable of positioning to have DEXA performed
4. Capable of undertaking the weight-bearing exercise regime
5. Capable of reading and understanding informed consent document
6. Able to self-administer PTH or have someone in the family who can do so
7. T score <-2.5 or Z score <-1.5 on evaluation of total hip BMD
8. No known endocrinopathies
9. Normal TSH levels
10. Normal 25-OH vitamin D levels
11. Normal calcium levels
12. Normal renal function (creatinine <2.0mg/dl)
13. Able to return for all follow-up visits

Exclusion Criteria:

1. Surgical or other intervention resulting in metal or anatomy precluding obtaining DEXA and/or MRI measurements
2. Other medical conditions that in the opinion of the investigator would preclude the subject from completing the study
3. History of malignancy
4. History of radiation therapy
5. Unable to self-administer PTH or have it administered
6. Elevated liver function tests >2x normal
7. For males, significantly abnormal free testosterone levels
8. Currently being prescribed anti-convulsants
9. Currently being prescribed glucocorticoids, other than inhaled glucocorticoids
10. Currently being prescribed any bone-active agents, including any bisphosphonate, raloxifene, hormone therapy (estrogen and estrogen/progestin), calcitonin or strontium-containing compounds.
11. No previous history of bisphosphonate use
12. No previous use of other bone-specific agents during past 2 years

Small numbers of subjects analyzed with considerable between-subject variability.