Metabolic bone disease Flashcards
Bone consists of (3)
Osteoblasts
Osteoclasts
Bone remodelling
cycles
What cell controls turnover
osteoblasts
How do we get VIT D
sunshine and diet
UV radiation - skin - chemical reaction
Chemical reactions of VIT D
7DHC
25 OH vit D (stored in lier fat and muscle)
kidney 1,25 Oh2 vit D
Where is calcium absorbed
gut under influence of vit d
maintaining extracellluar fluid calcium in a tight level for body functions
What is Paget’s disease of bone
- what does this cause and lead to?
Localised disorder of bone turnover
Increased bone resorption followed by increased bone formation
Leads to disorganised bone: bigger, less compact, more vascular and more susceptible to deformity and fracture
does Paget’s disease have a genetic component?
believe there is a?
YES- strong
15-30% are familial
environmental trigger
what is the major viral trigger for Paget’s
Possibility of chronic viral infection within Osteoclast
paget’s - symptoms (4)
always over 40, often over 60 in presentation
- deep seated bone pain all the time, often at night
- bone deformity
excessive heat over the Pagetic bone
- or by neurological complications such as nerve deafness
Common bones for Paget’s disease
long bone,
femur , tibia, fibia and humerus
pelvis , skull , forearm
Diagnostic tests for Paget’s
X-ray
isotope bone scan
Features of tests that may show Paget’s disease (5) (more rarely)
Isolated elevation of serum alkaline phosphatase-is the commonest presentation in the 21st centuary - liver test
- Bone pain and local heat
- Bone deformity or fracture
- Hearing loss
- Rarely the development of osteosarcoma in affected bone
Treatment of Paget’s Disease - what should you not treat on alone?
what therapy would yo use? - how is it given? is it repeated?
raised alkaline phosphatase
Intravenous Bisphosphonate therapy-One off zoledronic acid infusion
Paget’s is often a cause of ?
effectively managed by?
isolated elevation of serum alkaline phosphatase.
intravenous Bisphosphonates
What causes ricket’s in a growing child?
Severe nutritional vitamin D or Calcium deficiency causes insufficient mineralisation
What Is caused in the adult after severe insufficient mineralisation
Osteomalacia in the adult when the epiphyseal lines are closed
What is impaired in low Vit D states
Muscle function
what does vit D - STIMULATE
absorption of calcium and phosphate from the gut and calcium and phosphate then become available for bone mineralisation
Features of a child with rickets
- Abnormal bony shape
- stunted growth
- large skull - frontal bossing
- rib shape - rickety rosary
- protruded abdomen
how is rickets treated in children
vitamin D and calcium supplements
Osteomalacia in adult common in?
symptoms? (3)
- seen more common in?
elderly - house bound
bone pain, muscle weakness, increased falls risk
asian
Where can you see micro fractures in osteomalacia?
pelvis, ribs and long bones - looser bones
treatment of osteomalacia
calcium and vit d supplements
What is Osteogenesis Imperfecta - what is it characterised by?
Genetic disorder of connective tissue characterised by fragile bones from mild trauma and even acts of daily life
How many types of genetic Osteogenesis Imperfecta
28
Osteogenesis Imperfecta - type 1 , type 11, type 111, type 4
- describe them and the features
what types are they?
1: milder form-when child starts to walk and can present in adults
Type 11: lethal by age 1
Type 111: progressive
deforming with severe bone dysplasia and poor growth
Type 4 : similar to type 1 but more severe
collagen defects
Osteogenesis Imperfecta-other features (7)
Growth deficiency
Defective tooth formation (dentigenesis imperfecta) - baby teeth
Hearing loss
Blue sclera
Scoliosis / Barrel Chest
Ligamentous laxity
Easy bruising
management of OI
surgical
medical
social
genetic
surgical - to treat fractures
Medical - to prevent fracture intravenous Bisphosphonates
Social-educational and social adaptions
Genetic - genetic counselling for parents and next generation
osteoporosis characterised by
- what does this lead to ?
low bone mass and micro architectural deterioration of bone tissue,
- leading to enhanced bone fragility and a consequent increase in fracture risk
DXA bone scanning for osteoporosis ? menopause ?
The relevance of of osteoporosis is?
risk of fracture is related to?
risk of fracture
Age; BMD; Falls; and Bone Turnover
what tool used in osteoporosis
FRAX - risk fracture assessment tool
Q fracture - aged 30-85, men and women
Osteoporosis scanner when Q or FRAX is greater than??
what interferes with scan result?
10% - Prodigy Scanner
DEXTER
- L1-L4 in spine
- DXA scan of spine
- aorta calcification
- degeneration
What else is scanned with DXA for osteoporosis
HIP scan - t scores and z scores are generated for the bone density
lateral DXA scan
total body often scanned in children and those who are underweight
significant risk of osteoporosis fracture numbers?
a >10% risk of osteoporotic fracture over 10 years) the individual should be referred for a DXA scan ( Dual energy X-ray Absorptiometry)
who should be referred for a DXA scan regardless of their Fracture risk percentage?
All who are on oral steroids or suffer a low trauma fracture
How common is Osteoporosis?
I in 2 women over 50
I in 5 men over 50
If you suffer 1 vertebral fracture you are?
are 5 times more likely to have another and twice as likely to have hip fracture than if you had no vertebral fractures.
Endocrine causes of osteoporosis (6)
Thyrotoxicosis
Hyper and Hypoparathyroidim
Cushings
Hyperprolactinaemia
Hypopituitarism
Low sex hormone levels
in pregnancy and breast feeding bone can be lost
Rheumatic causes of osteoporosis (3)
Rheumatoid arthritis
Ankylosing Spondylitis
Polymyalgia Rheumatica
Gastroenterological causes of osteoporosis? (3)
ones in the liver and malabsorption
Inflammatory diseases: UC and crohns
Liver diseases: PBC, CAH, Alcoholic cirrhosis, Viral cirrhosis (Hep C)
Malabsorption: Cystic Fibrosis, chronic pancreatitis, coeliac disease, whipples disease, short gut syndromes and ischaemic bowel
Medications which cause osteoporosis (6)
Steroids
PPI
Enzyme inducting antiepileptic medications
Aromatase inhibitors
GnRH inhibitors
Warfarin
Peak bone mass age around- when does accelerated loss occur?
30 years old
- menopause
How to we prevent osteoporotic fractures?
Minimise risk factors - non smokers, alcohol intake
- Ensure good calcium and Vitamin D status
Falls prevention strategies
Medications
Medications that help prevent fractures
what are the side effects? (3)
Hormone replacement therapy
Increased risks of blood clots
Increased risk of breast cancer with extended use into late 50s/early 60s
Increased risk of Heart disease and stroke if used after large gap from menopause
What are SERMS
Selective oEstrogen Receptor Modulator-Raloxifene
Raloxifene reduces risk of ?
vertebral fractures
Negative Effects of SERMS? (3)
Hot flushes if taken close to menopause
Increased clotting risks
Lack of protection at hip site
- help reduce the risk of breast cancer
Bisphosphonates are?
features required to use this mediation?
Oral Bisphosphonates generally the first line of treatment
Adequate Renal function required Adequate Calcium and Vitamin D status Good Dental Health and Hygiene advised Notify dentist on Bisphosphonates Encourage regular check ups / well fitting dentures
EGFR for Bisphosphonates
oral - less than 30
IV - less than 45
Side effects of Bisphosphonates?
- Oesophagitis
- Iritis/uveitis
- heartburn
Not safe when eGFR<30 mls/min
ONJ - osteonecrosis of jaw
Atypical femoral shaft fractures
What is Denosumab
what does it reduce?
how is it given?
Monoclonal antibody against RANKL
Reduces osteoclastic bone resorption
Subcutaneous injection every 6 months - reduces bone break down but closer to recovery
Denosumab is after in patients with?
significant renal impairment then bisphosphonates
Denosumab blocks????
Osteoclast Formation, Function, and Survival Inhibited
Side effects of Denosumab?
reserve it for?
Allergy/rash
Symptomatic hypocalcaemia if given when vitamin D deplete
ONJ
Atypical femoral shaft fractures - rebound fracture
- older individuals
only licensed anabolic therapy for bone?
how is it given?
TERIPARATIDE: Intermittent Human Parathyroid Hormone
single daily injection
Side effects of Teriparatide? (3)
minor
- Injection site irritation
- Rarely hypercalcaemia
- Allergy
not suitable for children
