Metabolic Bone Disease Flashcards
What will insufficient vitamin D + calcium cause
- Insufficient mineralisation (vit D stimulates Ca + phosphate absorption from gut)
- Rickets in children
- Osteomalacia in adults, when epiphyseal lines are closed
- Muscle function also impaired in low vit D states
Appearance of Ricket’s
- Large forehead
- Odd curve to spine
- Odd-shaped ribs + sternum
- Large abdomen
- Wide elbow, wrist and ankle joints
- Odd-shaped leg
- Stunted growth
Describe Paget’s disease
-Localised disorder of bone turnover
-Increased bone resorption followed by increased bone formation
-Leads to disorganised bone:
Bigger
Less compact
More vascular
More susceptible to deformity fracture
Cause of Paget’s disease
- Strong genetic component
- Possibility of chronic viral infection within osteoclast
Symptoms of Paget’s disease
- > 40 years
- Bone pain
- Bone deformity (occasionally)
- Excessive heat over pagetic bone
- Nerve deafness
Typical presentation of paget’s disease
- Isolated elevation of serum alkaline phosphatase (commonest presentation)
- Bone pain + heat
- Hearing loss
- Bone deformity or fracture
- Osteosarcoma of affected bone (RARE)
Treatment of Paget’s disease
IV bisphosphonate therapy (one off IV zoledronic acid)
When and when not treat Paget’s diseases
- Don’t treat asymptomatic paget’s disease unless involving skull or area requiring surgical intervention
- Symptomatic paget’s disease requires treatment
What is Osteogenesis Imperfecta
- Genetic disorder of connective tissue
- Characterised by fragile bones
- Fractures from mild trauma or acts of daily life
Clinical range of OI
Prenatally fatal to 40 year olds presenting with “early osteoporosis”
4 types of OI
- Type 1 = Milder form, presents when child starts walking (can be present in adults)
- Type 4 = Similar to type 1 but more severe
- Type 11 = Lethal by age 1
- Type 111 = Progressive deforming with severe bone dysplasia + poor growth
8 OI symptoms
- Growth deficiency
- Defective tooth formation (dentigenesis imperfecta)
- Hearing loss
- Scoliosis
- Barrel chest
- Ligamentous laxity
- Easy bruising
- Blue sclera
Management of OI
- Surgical (treat #s)
- Medical (prevent #s with bisphosphonates)
- Social adaptions
- Genetic (genetic counselling for parents + next generation)
Define osteoporosis
-Micro architectural deterioration of bone resulting in increased risk of fracture
or
-Thin bones with increased risk of low trauma fracture
What is fracture risk related to
- Age
- BMD
- Falls
- Bone turnover
T score of > -1, -1 - -2.5 and > -2.5 suggest what management
- -1 = Reassure + Lifestyle advice
- -1 to -2.5 = Lifestyle advice (treat if previous fracture)
- > -2.5 = Lifestyle advice + offer treatment
2 fracture risk assessment tools
- FRAX
- QFracture
When should a patient be referred for a DEXA scan
FRAX or QFracture score = >10% fracture risk at any site over next 10 years
Treatment threshold for osteoporosis
~20% 10 year fracture risk
What BMD T-score suggests osteopenia
-1 to -2.5
3 risk factors for fracture
- FHx (main)
- Glucocorticoids
- Prior fracture
Limitations of FRAX
- Does not account for all known risk factors (e.g. falls)
- Lacks detail on some risk factors (dose response to glucocorticoids)
- Model relevant only for untreated patients
Describe the use of QFracture
- Applicable for men + women aged 30-85
- Contains multiple variable (CVS risks, falls, TCA)
Limitations of QFracture
- Does not have the ability to add BMD
- Some variable and risks can not be altered by osteoporotic medications
Causes of secondary osteoporosis
- Amenorrhea
- Drugs
- Endocrine
- Malabsorption
- Malignancy
- Rheumatic
Amenorrhea causes of osteoporosis
- Anorexia nervosa
- Early menopause
- Primary ovarian failure
Drug causes of osteoporosis
- Steroids
- Heparin + warfarin
- Anticonvulsants
- PPIs
Endocrine causes of osteoporosis
- Hyperthyroid
- Hyperthyroid + Hypothyroid
- GH deficiency
- Cushing’s
- Hyperprolactinaemia
Malignant causes of osteoporosis
Myeloma
Malabsorption causes of osteoporosis
- Coeliac
- CF
Rheumatic causes of osteoporosis
- RA
- Ankylosing spondylitis
- PMR
How to prevent osteoporotic fractures
- Minimise risk factors
- Good Ca + Vit D status
- Fall prevention strategies
- Medications
Treatment of osteoporosis
- Bisphosphonates (oral) (first line)
- Parathyroid Hormone Analog (teriparatide)
- Monoclonal antibody against RANK ligand (Denosumab)
- HRT
- Selective oEstrogen Receptor Modulator (SERM)
Side effect of HRT
- Increased risk of blood clots
- Increased risk of breast cancer with extended use in late 50s/early 60s
- Increase risk of heart disease + stroke if used after large gap from menopause
Side effects of SERMs
- Hot flushes if taken close to menopause
- Increased clotting risk
- Lack of protection at hip site
Problems with bisphosphonates
-Adequate renal function required
-Adequate Ca + Vit D required
-Good dental health + hygiene advised
Notify dentist about bisphosphonates + encourage regular check-ups and good fitting dentures
How do nitrogen containing bisphosphonates work
They inhibit osteoclasts
Side effects of bisphosphonates
- Oesophagitis
- Iritis/Uveitis
- ONJ? + Atypical femoral shaft fractures?
What is done to minimise the problems of patients taking bisphosphonates
- Drug holiday for 1-2 years
- Usually after 10 years of oral bisphosphonates
Side effect of teriparatide
- Injection site irritation
- Rarely hypercalcaemia
- Allergy
- COST
Side effects of denosumab
- Allergy/rash
- Symptomatic hypocalcaemia if give when Vit D deplete
- ?Atypical femoral shaft fractures
How does denosumab work
- Binds to RANK ligand
- Which inhibits osteoclast formation, function and survival
Why use denosumab and how is it taken
- Subcutaneous injection every 6 months
- Safer in patients with significant renal impairment than bisphosphonates
