Effect of Parathyroid Hormone (PTH) and Weight-Bearing on Bone in Spinal Cord Injury (SCI)

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