Week 1 Cortext - Biochemistry

Question 1

what are the characteristics of osteoporosis and what does this cause?

Answer 1

reduced bone mineral density
increased porosity (normal bone, just not enough of it)
leads to increased fragility and fracture risk

Question 2

what is the WHO definition of osteoporosis?

Answer 2

bone mineral density less than 2.5 standard deviations below the mean peak value of young adults of same race and sex

Question 3

what is osteopenia?

Answer 3

intermediate stage where bone mineral density is between 1-2.5 standard deviations below mean peak value

Question 4

what causes loss of bone mineral density?

Answer 4

mostly a normal physiological process which starts around 30 years old with a gradual slowing of osteoblast activity

Question 5

why do female tend to lose more bone mineral density?

Answer 5

after the menopause a loss of the protective effects of oestrogen results in an increase in osteoclastic bone reabsorption

Question 6

what are the 2 types of osteoporosis?

Answer 6

post menopausal osteoporosis

osteoporosis of old age

Question 7

what is post menopausal osteoporosis?

Answer 7

exacerbated loss of bone in the post menopausal period

risk factors include early menopause, smoking, alcohol, lack of exercise, poor diet, Caucasian race

Question 8

what types of fractures typically appear in post menopausal osteoporosis?

Answer 8

colles fractures

vertebral insufficiency fractures

Question 9

what is osteoporosis of old age?

Answer 9

greater decline in bone density with age than expected

risk factors similar to type 1 as well as chronic disease, inactivity and reduced sunlight exposure (vit D)

Question 10

what types of fractures often appear in osteoporosis of old age?

Answer 10

femoral neck fractures

vertebral fractures

Question 11

how else can osteoporosis occur?

Answer 11

secondary to other conditions
corticosteroid use
alcohol
malnutrition
chronic disease (cancer, rheumatoid arthritis etc)
endocrine disease (cushings etc)

Question 12

how is osteoporosis diagnosed?

Answer 12

DEXA scan (shows bone mineral density)
Normal serum calcium and phosphate levels

Question 13

can osteoporosis be cured?

Answer 13

no

treatments cant increase bone mineral density but can try and prevent further damage

Question 14

how can osteoporosis be prevented?

Answer 14

by building up bone density via exercise, diet healthy sun exposure throughout life

Question 15

how is osteoporosis treated?

Answer 15

bisphosphonates (1st line) - reduce osteoclastic reabsorption
Desunomab (monoclonal antibody which reduces osteoclast activity)
strontium (increases osteoblast replication and reduces absorption)
Yearly zoledronic acid injection
calcium and Vit D supplements

Question 16

what treatment can be used if the other common ones cause side effects?

Answer 16

HRT

can help prevent post menopausal osteoporosis but gives increased cancer risk

Question 17

what is osteomalacia?

Answer 17

qualitative defect of bone with abnormal softening of bone due to deficient mineralisation of osteoid (immature bone) secondary to inadequate amounts of calcium and phosphorus

Question 18

what is rickets?

Answer 18

same as osteomalacia but occurs in children and can cause effects in growing skeleton

Question 19

what causes osteomalacia/rickets?

Answer 19

insufficient calcium absorption from the intestines due to either lack of dietary calcium or deficiency/resistance to action of Vit D
OR
Phosphate deficiency caused by increased renal loss

Question 20

name some specific causes of osteomalacia/rickets

Answer 20

malnutrition
malabsorption
lack of sunlight exposure
hypophosphataemia
long term anticonvulsant use
chronic kidney disease

Question 21

what are the signs and symptoms of osteomalacia/rickets?

Answer 21

bone pain (mainly pelvis, spine and femora)
soft bone deformities
easily fracture
symptoms of hypocalcaemia

Question 22

what might a radiograph show in osteomalacia/rickets?

Answer 22

pseudofractures (loser’s zones), particularly in

• pubic rami
• proximal femora
• ulna
• ribs

Question 23

what is seen in biochemistry of osteomalacia/rickets?

Answer 23

low calcium
low serum phosphate
high serum alkaline phosphatase

Question 24

how is osteomalacia/rickets treated?

Answer 24

Vit D therapy

calcium and phosphate supplements

Question 25

quantitative vs qualitative bone disorder?

Answer 25

``` quantitative = normal bone just not enough of it qualitative = bone quality not good ```

Question 26

what is hyperparathyroidism?

Answer 26

overactivity of the parathyroid hormones causing high levels of parathyroid hormone (PTH)

Question 27

what causes hyperparathyroidism?

Answer 27

benign adenoma, hyperplasia or rarely a malignant neoplasia of parathyroid glands

Question 28

what does hyperparathyroidism cause?

Answer 28

hypercalcaemia and subsequent symptoms/signs

Question 29

what are the signs and symptoms of hypercalcaemia?

Answer 29

``` fatigue depression bone pain myalgia nausea thirst polyuria renal stones osteoporosis ```

Question 30

what can cause secondary hyperparathyroidism?

Answer 30

secondary overproduction of PTH due to hypocalcaemia (from Vit D deficiency or CDK)

Question 31

what causes tertiary hyperparathyroidism?

Answer 31

when adenoma develops in people with chronic secondary hyperparathyroidism which continues to produce PTH despite biological correction

Question 32

how does hyperparathyroidism appear on biochemistry?

Answer 32

high serum PTH high calcium normal/low phosphate

Question 33

what complications can arise from hyperparathyroidism?

Answer 33

fragility fractures lytic lesions in bone - brown tumours - osteitis fibrosa cystica

Question 34

how is hyperparathyroidism treated?

Answer 34

lytic lesions may need skeletal stabilization removal of adenomatous glands treat cause - Vit D supplements etc

Question 35

what is renal dystrophy?

Answer 35

reduced phosphate excretion and inactive activation of vit D results in secondary hyperparathyroidism with subsequent osteomalacia, sclerosis of bone and calcification of soft tissue

Question 36

what is pagets disease?

Answer 36

increased osteoclast activity results in increased bone reabsorption osteoblasts become more active to try and counteract this and produce new bone which fails to remodel properly resulting bone is thickened, brittle, mis-shapen and can fracture easily

Question 37

what can cause pagets disease?

Answer 37

viral infection genetic defects exaggerated response to Vit D

Question 38

which bones are commonly affected in pagets disease?

Answer 38

``` pelvis femur skill tibia sometimes ear ossicles causing deafness ```

Question 39

how does pagets disease present?

Answer 39

can be asymptomatic and only be seen on X ray can cause arthritis deformity, pain and fractures are common high output cardiac failure can occur

Question 40

what is seen on biochemistry in pagets disease?

Answer 40

``` raised serum alkaline phosphatease normal calcium and phosphorus imaging - enlarged bone - thickened cortices - coarse thickened trabeculae - mixed areas of lysis and sclerosis ```

Question 41

how is pagets disease treated?

Answer 41

bisphosphonates (inhibit osteoclasts) calcitonin if extensive lytic disease joint replacement if needed