What are the common conditions and disorders that affect osteoblasts and osteoclasts?

Osteoblasts and osteoclasts are two types of bone cells that are critical to overall bone health. Any condition that affects these bone cells can impair the ability to grow and maintain strong bones. Common conditions and disorders that affect osteoblasts and osteoclasts include: 

• Osteoporosis: This is a condition that weakens the bones and makes them more fragile. Bones that are affected by osteoporosis are thinner, less dense, and more susceptible to breaking and fractures. With age, the bones loss their ability to regrow and repair themselves, putting older individuals at higher risk of osteoporosis.  
• Osteopenia: ‘Loss of bone density’ is the medical definition of osteopenia. In this condition the bones have insufficient mineral content and are weaker because of the lower bone density. This puts them at higher risk of broken bones and fractures. Osteopenia occurs naturally with age and can progress to osteoporosis if the bone continues to lose density. 
• Hyperparathyroidism: Enlargement of the parathyroid gland or over-production of parathyroid hormone can cause hyperparathyroidism, which leads to high phosphate levels and low calcium levels in the blood. This manifests as muscle weakness, bone or joint pain, and fatigue among other symptoms. 
• Paget’s Disease of the Bone or Osteitis Deformans: This is a rare chronic bone disorder that is characterized by both, excessive breakdown and excessive regrowth of the affected bone or bones. Paget’s disease of the bone may affect one or multiple bones is more common with age. An individual who has this disorder is more susceptible to bone fractures or breaks. Although any bones in the body may be affected by osteitis deformans, the skull, spine, pelvis and leg bones are most susceptible to this condition. Researchers have been unable to identify the exact cause of Paget’s disease of the bone though it is believed that genetic and environmental factors may play a role in its onset.