Metabolic Bone Disease Flashcards
What is osteomalacia?
Severe nutritional Vitamin D or calcium deficiency, causing insufficient mineralisation and ‘soft’ bones
What is vitamin D’s role in bone mineralisation?
Vitamin D stimulates the absorption of calcium and phosphate from the gut, calcium and phosphate then become available for bone mineralisation
What group is osteomalacia/Ricket’s most common in?
Children and elderly
When is the condition known as Rickett’s as opposed to Osteomalacia?
Rickets in a growing child and osteomalacia in the adult when the epiphyseal lines are closed
What causes osteomalacia?
Vitamin D deficiency
- Malabsorption
- Diet
- Lack of sunlight
Chronic pancreatitis
Chronic renal failure, as unable to hydroxylate vitamin D
Liver disease
Drug induced/anti-convulsants
How does Ricket’s present?
Growth retardation
Apathy/Irritability
Hypotonia
Deformities
- Wide joints
- Odd shaped ribs
- Persistent fontanelles/Large forehead
- Oddly curved spine
- Bow legged
How does osteomalacia present?
Bone pain/tenderness
Muscle weakness and aches
Proximal myopathy/waddling gait
Pathological fractures
What investigations are used in osteomalacia diagnosis?
Decreased serum 25-hydroxyvitamin D
Decreased Ca2+
Decreased phosphate
Increased PTH
Increased ALKP
Bone Biopsy
Xray
- Looser zones
- Osteopenia/radioluscent bone
DEXA scan, shows low bone mineral density
What are looser zones?
Thin band representing pseudo-fracture/fragility fractures
How is osteomalacia managed?
Vitamin D supplementation/colecalciferol
- 50,000 IU once weekly for 6 weeks
- 20,000 IU twice weekly for 7 weeks
- 4000 IU daily for 10 weeks
- Maintenance supplementary dose 800 IU or more per day should be continued for life after the initial treatment
What is Paget’s disease?
Chronic condition characterised by increased and disordered localised bone turnover
Describe the pathophysiology of Paget’s
Increased bone resorption (bone break down) followed by increased bone formation
Leads to structurally disorganised weaker bone
- Bigger
- Less compact
- More vascular
- More susceptible to deformity and fracture
What sex is more likely to be affected by Paget’s?
M>F
What age group is more likely to be affected by Paget’s?
>70s
Give risk factors for Paget’s
FH
Male
>Age
Northern latitude
How does Paget’s present?
Asymptomatic in 70% of cases, so most common finding is elevated ALKP
Bone deformity or fracture
- Large skull and bowing of legs
Excessive heat
Deep boring bone pain or due to impingement on nerves
Neurological complications
- Hearing loss due to compression of vestibulocochlear nerve
Rare development of osteosarcoma in affected bone
Which bones are most commonly affected by Paget’s?
Pelvis
Lumbar spine
Femur/long bones of the extremities
Skull
What investigations are used in diagnosis of Paget’s?
Isolated elevated ALKP
- Marker of osteoblastic activity
Normal Ca+ and Phosphate (PO4)
Xray
Bone biopsy, to exclude other conditions
What Paget’s signs are seen on X-Ray?
Thickened bone/dense areas
Lytic lesions/destruction of area of bone
How is Paget’s managed?
If asymptomatic, do not treat unless in skull or area requiring surgical intervention
Analgesia if pain
IV Bisphosphonate therapy, slows down bone lysis so move on to this if analgesia is not sufficient
One off IV zoledronic acid
Surgery
What surgical methods can be used in Paget’s management?
Correct bone deformities
Decompress impinged nerve
Give complications of Paget’s
Osteoarthritis if developing at a joint
Osteosarcoma
High output cardiac failure
Hypercalcaemia
Secondary immobility
What is Osteogenesis Imperfecta?
Genetic disorder of absent/defective type 1 collagen characterised by fragile bones and fractures
How many types of OI are there?
28
