Metabolic bone disease Flashcards
What is the biologically active form of vitamin D?
Calcitriol
What is Paget’s disease of bone?
Degenerative bone disease - localised disorder of bone turnover
What happens pathological in Paget’s disease of bone?
Increased bone resorption followed by increased bone formation
Leads to disorganised bone: bigger, less compact, more vascular, more susceptible to fracture and deformity
What is the aetiology of Paget’s disease of bone?
Genetic: familial
Geographic distribution
Environmental trigger
What are the signs/symptoms of Paget’s disease of bone?
> 40yrs
Bone deformity
Excessive heat over Pagetic bone
Nerve deafness
What is the presentation of Paget’s disease of bone?
Isolated elevation of serum alkaline phosphatase (ALP)
Bone pain/local heat
Bone deformity/fracture
Hearing loss
Rare - development osteosarcoma in affected bone
When should you not treat Paget’s disease of bone?
Not treated if asymptomatic unless in skull/area requiring surgical intervention
Do not treat based on ALP raise alone
When you should treat Paget’s disease of bone, what is the treatment?
IV biphosphonate therapy
One of IV zoledronic acid
What group of drugs treat Paget’s disease of bone?
Bisphosphonates
What is Rickets/osteomalacia caused by?
Severe nutritional vitamin D or calcium deficiency causes insufficient mineralisation
What is the difference between Ricket’s and osteomalacia?
In children, the disease is rickets but after fusion of the epiphyseal plates it is known as osteomalacia
Why is vitamin D important?
Stimulates the absorption of calcium and phosphate from the gut
Calcium and phosphate then available for bone mineralisation
What function is impaired in low vitamin D states?
Muscle function
What are the physical signs of Ricket’s in a child?
Generally unwell Stunted growth Odd curve to spine/back Odd-shaped legs, ribs, breast bones Wide bones/ankles Large abdomen Wide joints elbow/wrist Large forehead
What are some signs of Ricket’s?
Generally unwell
Delayed walking / crawling / sitting
Rachitic Rosary – bead like nodules on the ribs
Kyphoscoliosis
Bowed legs and ‘knock knees’ only occur in severe cases in older children
What are clinical signs of Ricket’s/osteomalacia?
Muscle aches Muscle weakness Bone pain/pain on walking Predisposition to fractures Tetany: parasthesia of lips, tongue, face
What is the treatment for Ricket’s/osteomalacia?
Vit D supplements
Calcium
What are the investigations for Ricket’s/osteomalacia?
Vit D ALP PTH Calcium Phosphate XR
What is osteogenesis imperfecta (OI)?
Genetic disorder of connective tissue characterised by fragile bones from mild trauma and acts of daily life
What is OI caused by?
Defects in type 1 collagen
What are the 4 most common types of type 1 collagen defect seen in OI?
Type I: mild, when child starts to walk, can present in adults
Type II: lethal by age 1
Type III: progressive deforming with severe bone dysplasia and poor growth
Type IV: similar to type I but more severe
What are other signs/symptoms of OI?
Growth deficiency Defective tooth formation Hearing loss Blue sclera Scoliosis Barrel chest Ligamentous laxity Easy bruising
What are the different approaches to management of OI?
Surgical: treat fractures
Medical: prevent fractures with IV bisphosphonates
Social: adaptations
Genetic: genetic counselling
What is the medical management of someone with OI?
IV bisphosphonates
