Metabolic bone disease Flashcards
List three bone density related risk factors for osteoporosis
Malabsorptive conditionS- UC, coeliac, crohn’s
Chronic kidney disease
Chronic liver disease
Immobility
Oestrogen deficiency
Endocrine- diabetes, hyperthyroidism and hyperparathyroidism
BMI <18.5
List three risk factors for osteoporosis independent of bone density
age
oral corticosteroids
smoking
alcohol prev fragility fracture
RA + other inflammatory arthropathies
Name two drugs that are a risk factor for osteoporosis
SSRIs
PPIs
Aromatase inhibitors
GnRH in prostate cancer
What does DEXA measure?
calcium hydroxyapatite CaPo43OH
What are T scores and Z scores
T score- bone mineral density compared to young adult
Z score- compared to aged matched control
Where is DEXA measured?
L1-4 and femoral neck
What T score is defined as osteoporosis?
<-2.5
List one assessment tool for fracture risk
FRAX
Qfracture
Who should undergo assessment of fragility fracture?
women >65 and men >75
risk factors women >50-64 and men 50-74
Name two risk factors included in the fragility fracture risk assessment
A previous osteoporotic fragility fracture.
Current use or frequent recent use of oral corticosteroids.
History of falls.
Low body mass index (less than 18.5 kg/m2
Smoker.
Alcohol intake of more than 14 units per week.
List two non osteoporotic causes for fragility fractures
metastatic disease
myeloma
osteomalacia
paget’s
What is the treatment for osteoporosis?
Exercise – weight bearing activity
Reduce fizzy drinks (especially colas with phosphoric acid)
HRT for menopause < 40 years
Vitamin D alone if calcium intake satisfactory
Vitamin D with calcium if calcium intake inadequate
Name an example of biphosphonate
Alendronate
Risedronate
Zolendronate
Ibandronate
What is the MOA of biphosphonates?
Bisphosphonates inhibit the digestion of bone by encouraging osteoclasts to undergo apoptosis, or cell death, thereby slowing bone loss
but reduce bone turnover
Other than biphosphonates, list one other drug class for the treatment of osteoporosis
oestrogen receptor modulator- raloxifene
calcitonin- thyroid hormone
mAb- denosumab
What is osteomalacia also known as?
rickets= before skeletal maturity
What is osteomalacia?
softening of the bones caused by impaired bone metabolism primarily due to inadequate levels of available phosphate, calcium, and vitamin D, or because of resorption of calcium. The impairment of bone metabolism causes inadequate bone mineralization.
Where is rickets most prominent?
large physes- knee and wrist
List two causes of vitamin D dependent osteomalacia/rickets
Low exposure to UV radiation
Low oral intake
* Low dietary intake
* Breast milk has low amounts of vitaminD
Low intestinal absorption
* Cystic fibrosis
* Chronic pancreatitis
* Coeliac disease
* Gastrectomy
Renal disease
Alcoholisms
Hepatobiliary disease
List one vit D independent form of osteomalacia
Renal tubular acidosis
Fanconi syndrome
Drugs- bisphosphonates, fluoride, excessive use of phosphate-binding antacids (Aludrox)
What is the treatment of osteomalacia?
Replacement of missing component(s)
* Vitamin D
* Calcium (with or without vitamin D)
* Calcitriol (synthetic D3)
* Phosphate
* Surgical correction in selected cases
Trefoli pelvis is a sign on XR of which metabolic condition?
osteomalacia- lateral acetabular indentation
What are the symptoms/signs of osteomalacia?
Pain in bones and muscles
Proximal muscle weakness – waddling gait
Fractures
What is the aetiology of Paget’s?
viral- paramyxovirus + genetic
What is the pathophysiology of Paget’s?
disorder of bone remodelling
starts with increased osteoclastic activity
all three phases of bone remodelling may coexist
List two common fracture sites in paget’s
femur
tibia
pelvis
skull
spine
What are the biochemical features of paget’s
normal calcium and phosphate
Raised Alk phos
raised hydroxyproline
What are the symptoms’/signs of paget’s?
Localised pain and tenderness
Increased focal temperature due to hyperaemia (due to hypervascularity)
Increased bone size - historically changing hat size was a giveaway
Bowing deformities
Kyphosis of the spine
Decreased range of motion
75% asymptomatic at time of diagnosis
Name two complications of paget’s
osteoarthritis
pathological fractures
hearing loss
neural compression
malignancy
high output congestive heart failure
Cotton wool appearance of skull is a feature of which disease?
paget’s
What is tam o’shanter a sign of?
Paget’s-frontal bone enlargement, with the appearance of the skull falling over
the facial bones, like a Tam O’Shanter hat
What is blade of grass sign?
sign of paget’s in long bones on XR
Treatment of Paget’s?
biphosphonates
calcitonin
