Flashcards in CORTEX biochemistry Deck (59):
What is osteoporosis?
Reduced bone mineral density and increased porosity
Osteoporosis can be described as a quantitive defect, what does this mean?
The bone is normal but there's not enough of it
What does osteoporosis increase your risk of?
Fractures (i.e fragility fractures)
Define osteopenia and osteoporosis
Osteopenia - 1-2.5 SDs below mean
Osteoporosis - >2.5 SDs below mean
When does loss of bone density begin?
Describe physiological loss of bone density and mention the relevance of menopause
Slowdown of osteoblast activity with age
Increased osteoclastic bone reabsorption post-menopause due to reduced oestrogen
List the two types of primary bone osteoporosis
Type 1 post menopausal
Type 2 osteoporosis of old age
What are the risk factors for post menopausal osteoporosis?
Lack of exercise
Which types of fractures tend to occur in post menopausal osteoporosis?
What are the risk factors for osteoporosis of old age?
Reduced sunlight exposure (low vit D)
Which types of fractures tend to occur in osteoporosis of old age?
Femoral neck fractures
List the causes of secondary osteoporosis
Chronic disease (CKD, malignancy, rheumatoid arthritis)
Endocrine disease (cushing's, hyperthyroidism, hyperparathyroidism)
How is osteoporosis diagnosed?
Normal serum calcium
Normal serum phosphate
How is osteoporosis managed?
Vitamin D supplements
Monoclonal antibody (desunomab)
How is osteoporosis managed?
List some biphosphonates
IV zoledronic acid (once per year)
How do biphosphonates work?
Reduce osteoclast reabsorption
How does desunomab work?
Reduces osteoclast activity
How does strontium work?
Increases osteoblast replication and reduces absorption
Why is intranasal calcitonin not used to treat osteoporosis?
Increased cancer risk with no benefit over other treatments
HRT is recommended as first line treatment of osteoporosis in post menopausal women. T/F
False - considered if side effects with other medications
What are the risks of HRT?
What is raloxifene? What is the risk of it?
Oestrogen receptor modulator
Osteomalacia is a qualitative bone defect, what does this mean?
Bone quantity is normal but the quality is sub-par
What is osteomalacia?
Abnormal soft bones that have not been mineralised due to deficiencies in calcium and phosphorus
What is Rickets?
Abnormal soft bones that have not been mineralised due to deficiencies in calcium and phosphorus occuring in CHILDREN
What are the causes of osteomalacia and ricket's?
Lack of dietary calcium
Deficiency of vitamin D
Resistance to vitamin D
Phosphate deficiency (increased renal loses)
What are the specific pathologies which lead to osteomalacia and ricket's?
Lack of sunlight exposure
Long term anti-convulsant use
Chronic kidney disease
What are the causes of hydrophosphateamia?
Renal tubular acidosis
Which inherited renal diseases can be the cause of osteomalacia and rickets?
Vitamin D resistant ricket's
How does osteomalacia/ricket's present?
Bone pain (pelvis, spine, femur)
Is bony deformity more common in osteomalacia or ricket's?
How does hypocalcaemia present?
What may be typically seen on a radiograph of someone with osteomalacia or ricket's?
Pseudofractures (looser's zones) of pubic rami, proximal femur, ulna or ribs
How does osteomalacia/ricket's present biochemically?
Low serum phosphate
High serum alk phosphatase
How is osteomalacia/ricket's treated?
Vitamin D therapy
What is hyperparathyroidism?
Over activity of parathyroid glands (i.e high parathyroid hormone)
What causes primary hyperparathyroidism?
What is the result of primary hyperparathyroidism?
High PTH --> hypercalcaemia
How does primary hyperparathyroidism present biochemically?
How does hypercalcaemia present?
Groans (fatigue, depression)
What is secondary hyperparathyroidism?
Overproduction of PTH secondary to hypocalcaemia caused by CKD or vit D deficiency
What is tertiary hyperparathyroidism?
Patients with chronic secondary hyperparathyroidism develop a parathyroid adenoma producing ectopic PTH
What is usually the cause of chronic secondary hyperparathyroidism?
What bone problems can hyperparathyroidism cause? How are they treated?
Brown's tumours/osteitis fibrosa cystica (lytic bone lesions)
How is hyperparathyroidism treated?
Removal of cause (e.g adenoma, cancer, etc)
Treatment of cause (e.g vit D deficiency, etc)
How is hypercalcaemia treated?
What type of bone changes are caused by CKD? Why?
Secondary hyperparathyroidism causes osteomalacia, bone sclerosis and soft tissue calcification
Reduced phosphate excretion and inability to activate vit D
What is Paget's disease?
Chronic bone disease causing thick, brittle and deformed bones
How many bones does paget's disease affect? Which bones?
One or two
Pelvis, femur, skull, tibia
Which age groups are typically affected by Paget's?
> 55 (increasing age)
Which two factors may increase incidence of Paget's?
Describe the pathogenesis of Paget's disease
Increased osteoclast activity (exaggerated vit D response) -->
Increased bone turnover -->
Osteoblasts become more active in a bid to compensate -->
New bone does not remodel correctly -->
Brittle, easily fractured bone
What happens if Paget's occurs in ear ossicles?
How does Paget's disease present?
Asymptomatic until picked up on x-ray
High output cardiac failure
How does Paget's disease present biochemically?
High alk phosphatase
How does Paget's appear on an x-ray?
Enlarged bone with thickened cortices
Mixed lysis and sclerosis
How does Paget's appear on bone scans?
Increased uptake in affected bones