Metabolic Bone Diseases Flashcards
Rickets and osteomalacia Paget's disease of bone Osteogenisis Imperfecta Osteoporosis
7 signs and symptoms of osteogenesis imperfecta
Growth deficiency
Defective tooth formation
Hearing loss
Blue sclera
Scoliosis - barrel chest
Ligamentous laxity
Easy bruising
Osteogenesis imperfecta
Treatment (4)
Medical - IV bisphosphonates to prevent fractures
Surgical to treat fractures
Social
Genetic
Rickets and osteomalacia
3 step pathogenesis
Severe nutritional vitamin D or calcium deficiency
Causing insufficient mineralisation
Resulting in soft weak bones
Why does vitamin D deficiency cause rickets/osteomalacia?
Vitamin D stimulates calcium absorption and phosphate from gut
Paget’s disease of the bone
Definition (4)
Localised disorder of bone turnover
Increased bone resorption
Increased bone formation
Caused disorganised bone formation
Describe bone structure in paget’s disease of the bone
Disorganised bone features (3)
- Bigger
- Less compact
- More vascular
So more susceptible to deformity and fracture
Paget’s Disease of the bone
Etiology
- Genetic
- Ethnicity
- Environmental trigger (1)
Which factor is the strongest component?
Familial
Loci of SQSTM1
Anglo-saxon origin
Environmental trigger: chronic viral infection of osteoclast
Paget’s Disease of the bone
Symptoms (4)
- Describe the classical patient (1)
- Presentation (4)
- Which is the commonest presentation?
- >40 yo with bone pain
- Occasionally presents with bone deformity/fracture
- Occasionally presents with excessive heat over Pagetic bone
- Isolated elevation of serum alkaline phosphatase
- Osteosarcoma in affected bone - rare
Commonest presentation - isolated elevation of serum alkaline phosphatase
Paget’s disease of the bone
Treatment (1)
Intravenous bisphosphonate - zolendronic acid
Osteogenesis Imperfecta
Definition (4)
Genetic disorder of connective tissue
characterised by fragile bones
stemming from mild trauma
Type 1 collagen
Osteogenesis Imperfecta
Type 3 collagen
Progressive deforming
severe bone dysplasia
poor growth
Osteogenesis Imperfecta
4 sign and symptoms
- Name 4 bone related manifestations of the disease
Growth deficiency
Bone-related manifestations
- Defective tooth formation
- Hearing loss
- Scoliosis - barrel chest
- Ligamentous laxity - hypermobility
Blue sclera
Easy bruising
Osteoporosis Definition (5)
Metabolic bone disease
characterised by low bone mass
micro-architectural deterioration of bone tissue
leading to enhanced bone fragility
consequent increase in fracture risk
When does accelerated bone mass decline begin in a female?
Accelerated bone mass decline begins after menopause
When is DEXA bone scanning is done in post-menopausal women, what T-score is used to diagnose osteoporosis?
What T-score (range) for osteopenia
<2.5 SDs below young adult mean is diagnostic of osteoporosis in a DEXA bone scanning
-1 to -2.5 for osteopenia
FRAX vs Q fracture scores
FRAX is age, BMD and country specific
Q Fracture considers more variables but not BMD
Whats the treatment threshold for osteoporosis
Fracture risk 20% in 10 years
Causes of secondary osteoporosis (6)
(state headings)
- Endocrine
- Malabsorption
- Malignancy
- Rheumatic
- Drugs
- Amenorrhea
State 6 endocrine causes of secondary osteoporosis
Hyperthyroidism
Hyperparathyroidism, Hypoparathyroidism
Growth hormone deficiency
Hyperprolactinemia
Cushing’s disease
Name 4 malabsorptive diseases that are secondary causes of osteoporosis
Celiac disease
CF
Pancreatitis
Whipple’s disease
Name 3 auto-immune inflammatory joint conditions that cause osteoporosis and their pathogenesis (one word)
Rheumatoid arthritis - Rx, inactivity
Ankylosing spondilytis - syndesmophytes, inactivity
PMR - increased bone resorption
Name 6 (types) of drugs that cause osteoporosis
- Steroids - long term use
- Anticoagulants
- Heparin
- Warfarin
- Anticonvulsants
- PPI’s
- GNRH inibitors - GH deficiency
- Aromatase inhibitors - hypoestrogenism
Name hypoestrogenism illnesses that cause osteoporosis
1 + 3 things that cause amenorrhea
Hyperprolactinemia
Amenorrhea
- Primary ovarian failure
- Anorexia nervosa
- early menopause
Name 5 drugs used in treatment of osteoporosis
- HRT
- SERMs
- Bisphosphonates
- Teriparatide - PTH analogue
- Denosumab - Rankl ab
Name 4 modalities of osteoporosis mx
- Minimise risk factors
- Ensure good calcium and vitamin D intake
- Falls prevention strategies - social
- Medications
Denosumab
MOA, dosing, SE [3], instructions for discontinuing
Mab to RANKL
Subcut injections 6 monthly
SE: cellulitis, eczema, osteonecrosis of jaw
If discontinued must start patient on IV zolendronate to lock in all benefits otherwise rebound bone-remodelling
Bisphosphonates
MOA
Name 4 and identify the most potent
SE [3]
MOA: inhibits bone resorption
Risendronate, alendronate, ibandronate, IV zolendronate*
SE: osteonecrosis of jaw, atypical subtrochanteric #, flu like illness
Teriparatide
ROA and duration
MOA
SE [2]
ROA, duration: OD, subcut injection 18m
MOA: stimulates osteoblast activity (note endogenous PTH causes catabolic effectts but given intermittently has opposite effect)
SE: GI upset, renal toxicity
Your patient has been on bisphosphonates for a while and asks if she can take a break from them. What do you do? [3]
ASSESS: After 5y of oral or 3y IV bisphosphonates do updated FRAX score and DEXA scan
Bisphosphonate holidays: after assessment you determine whether their high or low risk. What do you do if the patient is:
- High risk
- What is considered high risk? [5]
- Low risk [3]
If high risk
- continue bisphosphonates indefinitely
- >75y/o, glucocorticoid therapy, previous hip or vertebral #, high risk on FRAX or T score <-2.5 after mx
If low risk:
- discontinue and reassess in 2y or if another # occurs
