Bone conditions Flashcards
Pagets disease
Focal bone resorption followed by excessive and chaotic bone deposition Affects (in order): spine, skull, pelvis and femur Serum alkaline phosphatase raised (other parameters normal) Abnormal thickened, sclerotic bone on x-rays Risk of cardiac failure with >15% bony involvement Small risk of sarcomatous change
Osteoporosis
Excessive bone resorption resulting in demineralised bone Commoner in old age Increased risk of pathological fracture, otherwise asymptomatic Alkaline phosphatase normal, calcium normal
Secondary Bone tumours
Bone destruction and tumour infiltration Mirel scoring used to predict risk of fracture Appearances depend on primary (e.g.sclerotic - prostate, lytic - breast) Elevated serum calcium and alkaline phosphatase may be seen
How does Osteogenesis Imperfecta present?
Bone pain/tenderness Proximal muscle weakness Back pain Stress fractures (looser zones)
What blood results would you see in vitamin D deficiency?
Low serum 25(OH) vit D levels Serum PTH increased Serum Calcium low/normal Serum phosphate low ALP increased due to osteoclast activity
Causes of vit D deficiency
Inadequate sunlight or diet Malabsorption (small bowel resection or cystic fibrosis) Phenytoin and rifampicin. Multiparosity, liver and renal disease impacting vit D metabolism, Hypophosphataemia and rare congenital disorders.
How do you treat osteomalacia imperfecta?
Vit D (oral alphacalcidol (1,25 (OH) Vit D) has a risk of hypercalcaemia)
What are the effects of vitamin D deficiency?
Low vit D - reduces Ca2+ gut absorption - low serum Ca2+ - Increase PTH (2ndry hyperparathyroidism) Ca2+ absorbed from one – Reduced bone mineralisation (soft bones)
What are the actions of vitamin D?
– Maintain calcium homeostasis – Maintain bone health – Increase Ca2+ from the gut – Increase phosphate absorption from gut – Osteoclast function / maturation
What is Pagets Disease
Disordered bone metabolism – Osteoclast overactivity – Followed by compensatory osteoblast activity – Leads to disordered ‘woven’ mosaic bone – Weaker than normal bone • Second most common bone disorder in elderly – 70-90% asymptomatic
What bones does Pagets tend to effect?
Can affect one (monostotic) or more (polyostotic) bones • Any bone, but commonly – Spine – Pelvis – Skull – Femur • Rarely – Hands – Feet – Fibula
How does Pagets disease present?
• Symptoms – Direct • Bone pain – Deep, constant, boring pain – Worse on weight-bearing • Pathological fracture • Sarcomatous change – rare – Indirect • High cardiac output • Compression effects depending on site Compressive effects – Skull • Cranial nerve palsies • Deafness (CN VIII - vestibulocochlear) • Basilar invagination – Spine • Sciatica / nerve root entrapment • Cauda equina syndrome – Paraplegia
How is Pagets disease diagnosed?
Diagnosis – X-ray • Incidental / directed – Blood tests • High alkaline phosphatase (NB. liver disease) • Normal calcium, vitamin D, PTH, phosphate – Urinary hydroxyproline increased – Isotope bone scan – increase uptake
How is Pagets disease treated?
Treatment – Not everyone! • Symptomatic • In danger of nerve compression • Around a weight-bearing joint – Bisphosphonates • Risedronate – 30mg daily 2 months • Zolendronate – 5mg x 1 infusion
What biochemical differences are seen in different bone disorders?
