metabolic bone disease Flashcards
What cells are involved in bone formation?
1- Mesenchymal progenitor cell
2- Pre-osteoblast
3- Osteoblast
what cells are involved in bone resorption?
1- Myeloid progenitor cell
2- Pre-Osteoclast
3- Osteoclast
what stimulates osteoclast resorption
- Osteoblasts release RANK
- Pre-fusion osteoclast has RANK Ligands on its surface which RANK binds to and stimulates the development of osteoclasts
what stimulates osteoblast formation?
- Gluco-corticoids
- Vitamin D
• Produced by skin
• Produced by liver
• Produced by kidney - IL-11
- TNF-alpha
- PTH
- IL-1
- PTHrP
- PGE2
what is involved in Paget’s disease
Localised disorder of bone turnover
1- Increased bone resorption
2- followed by increased bone formation
Leads to disorganised bone: bigger, less compact, more vascular and more susceptible to deformity and fracture
Aetiology of Paget’s disease?
Strong genetic component
15-30% are familial
Loci of SQSTMI
Restricted geographic distribution: those of Anglo-Saxon origins
Environmental trigger: Possibility of chronic viral infection within Osteoclast
what investigations are carried out?
- Isolated elevation of serum alkaline phosphatase
- Normal calcium and phosphatase
Imaging:
- may show lytic lesions
- may show increased resorption
what are the symptoms of pages disease?
- Bone pain
- Bone deformity/ fracture
- XS heat over pagetic bone
what are the complications of pagets disease?
- Nerve compression due to bone overgrowth : nerve deafness
- Osteosarcoma
How is pagers disease treated?
- If asymptomatic- do not treat unless in skull
- Do not treat on raised alkaline phosphatase alone
- IV bisphosphonate therapy- one off IV ZOLEDRONIC ACID
What is the pathogenesis of Rickets and osteomalacia?
Normal amounts of bone but abnormal amount of mineralization
- Severe Vitamin D/ calcium deficiency
- Leads to insufficient mineralization
- Rickets in a growing child
- Osteomalacia in an adult when the epiphyseal lines are closed
what is the aetiology of rickets and osteomalacia?
- Vitamin D deficiency
- Vitamin D resistance : mainly genetic
- Liver disease
- Tumour induced osteomalacia
- Renal osteodystrophy
what are the investigations carried out in rickets and osteomalacia
- Plasma: decreased phosphatase,Increased ALP
- Biopsy: shows incomplete mineralization
- X-ray: loss of cortical bone; Partial fractures
presentation of Rickets
- Stunted growth
- Large forehead
- Odd curve to spine/ back
- Odd shape to ribs/breast bones
- Large abdomen
- Wide joints at elbow and wirst
- Odd shaped legs -bow shaped
- Wide ankles
- Hypotonia
what is the presentation of osteomalacia?
- Bone pain/ tenderness
- Fractures
- Myopathy
