Week 4 - I - Osteoporosis and bone disorders Flashcards
Progressive systemic skeletal disease characterised by low bone mass and microarchitectural deterioration of bone tissue, with a consequent increase in bone fragility and susceptibility to fracture - hard brittle bones
What is this?
Osteoporosis
What is the condition which refers to a softening of your bones, often caused by a vitamin D deficiency? Soft bones are more likely to bow and fracture
Osteomalacia
Is osteoporosis more common in men or women?
Osteoporosis is more common in women
What are the 4 common fracture sites for osteoporosis?
Neck of femur
Vertebral body
Hip
Humeral neck
What percentage of people with hip fractures die within a year of the fracture?
20% of people with hip fracture die within a year of the fracture
What age group do the majority of hip fractures of osteoporosis occur in?
The majority of hip fractures occur in women over 75
About 10% of the adult skeleton is remodelled each year How does the remodelling process take place? (what materiel is mineralized)
Bone undergoes a cycle of remodelling in a programmed sequence at discrete foci called bone remodelling units
Osteoclasts appear and begin to resorb bone, the osteoclasts are then replace by osteoblasts that fill the cavity made by producing osteoid which is mineralised to form new bone
In osteoporosis, how does the bone remodelling cycle differ which causes the brittle bone? (left pic is osteoporosis, right is normal)
In osteoporosis, the rate of osteoclasts activity is greater than osteoblast activity leading to the increased bone loss
Resorption greater than formation
What factors lead to an increased bone loss? (eg drugs, gender, hormones, what type of breast cancer)
Drugs - glucocorticoids lead to increased bone loss
Gender - females
Hormones - sex hormone deficiency causes bone loss (aromatase inhibitors in hormone receptor-positive breast cancer)
Menopause in women - decreased androgen leads to decreased oestrogen leads to bone loss
What hormone deficiency is the major determinant of bone loss after the menopause ?
Oestrogen deficiency
What are usually the factors that cause a person to be assessed for bone fractures? (the two sites are frax and QFracture)
Anyone over the age of 50 years
Anyone under 50 years with very strong clinical risk factors - Early menopause, Glucocorticoids
What is the most widely used method of measuring bone mineral density?
A DEXA scan
What is the normal standard deviation for bone mineral density?
Normal : BMD within 1 SD of the young adult reference mean
Osteopenia a medical condition in which the protein and mineral content of bone tissue is reduced, but less severely than in osteoporosis. What is the bone mineral density of bones with osteopenia? (standard deviation) What is osteoporosis BMD?
Greater than 1 but less than 2.5 standard deviations below the young adult mean
Osteoporosis is BMD greater than 2.5 SD below the young adult mean
What are some secodnay causes of osteoporosis? (endocrine, GI and resp)
Endocrine eg hyperthyroidism, hyperparathyroidism, Cushing’s disease
Gastrointestinal eg coeliac disease, IBD, chronic liver disease, chronic pancreatitis
Respiratory eg CF, COPD
How can hyperthyoridism cause osteoporosis?
Too much thyroxine can increase the rate of bone turnover and if the body cannot keep up the rate of new bone formation then this will decrease the bone mineral density
What should be avoided to decrease risk of osteoporosis?
Avoid smoking and alcohol
And glucocorticoids if possible
What is the recommended nutrient intake of calcium in the diet?
700mg calcium minimum
In people who are at a deficiecny of sunlight exposure, and are therefore at a risk of fractures, what supplements can be given to help?
Give calcium and vit D supplements
Your T-score is the number of units — called standard deviations — that your bone density is above or below the average. What does the T score have to be to give the first line treatment for osteoporosis? What is the first line treatment? (the drug type and example)
T score less than -2.5
First line treatment is oral biphophonates - alendronic acid (alendronate) or risendronic acid (risendronate)
If the patient is not suitable for oral biphosphonates what is given? (this is also the second line treatment) How is it given?
Zolendronic acid - it is a once yearly IV infusion for 3 years
fully human monoclonal antibody used in treatment of osteoporsis - high risk fracture patients Given as 6monthly SC injections WHat is this? (alternative second line)
Denosumab
What is a rare side effect of long term biphosphonate treatment? (and two other side effects)
Damage to the jaw bone (osteonecrosis)
Oesophagitis
Hypocalcaemia / tired
What are three side effects of denosumab?
Eczema Cellulits Hypocalcaemia
If patient has severe spinal osteoporosis, what should be considered for bone treatment?
Teriparatide - recombinant parathyroid hormone
What is final line treatment for osteoporosis if other treatments do not work or are contra-indicated?
Strontium ranelate
Contra-indicated in history of vascular disease
When are the majority of treatments considered for treatment with an anti-resorptive agent?
When when T score = - 2.5
What are the direct effects that glucocorticoids have on bone?
Decrease osteoblasts activity
Reduction in calcium absorption
What is the disease of the bone characterized by abnormal osteoclasts activiity followed by increased osteoblastic activity?
Paget’s disease of the bone - causes abnormal bone structure with reduced strength and increased fracture risk
How is paget’s diagnosed? (what scan and what is biochemistry findings)
diagnose on XR,
isotope bone scan shows distribution
raised alkaline phosphatase with normal LFTs (normal calcium, phosphorus and PTH)
How is paget’s treated?
Give biphosphonates and analgesics for pain
rare group of genetic disorders mainly affecting bone most secondary to mutations of type 1 collagen genes Causes blue sclera What is this?
Osteogenesis imperfecta or brittle bone disease
