A loss of bone mineral density, leading to weak bones that easily fracture. Some causes include a drop in testosterone or estrogen levels, certain medications, improper nutrition, malabsorption, certain diseases (e.g., IBD, Addison's Disease, Hypothyroid or Hyperparathyroid), and possibly other causes. Protein deficiency can lead to loss of bone density, as can calcium and other mineral deficiencies. A Bone Density Test (DEXA Scan) is required for diagnosis. Special Osteoporosis medication may be needed to slow the progression of bone density loss.