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CP > Diseases of Bone and Application of New Markers > Flashcards

Diseases of Bone and Application of New Markers Flashcards

1
Q

What are the two layers of bone and what are they like?

A

Cortical bone - hard outer layer, makes up 80% of bone. Forms columns that hold vessels/nerves
Trabecular bone - spongy inner layer that holds bone marrow

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2
Q

What separates the cortical and trabecular layers of bone?

A

endosteum

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3
Q

What are the extracellular components of bone?

A

collagen
hydroxyapatite
calcium, phosphate

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4
Q

What are osteoblasts?

A

outside of bone
already mineralised
makes osteroid (bone)
makes hormones, matrix proteins and alkaline phosphatase
get buried/trapped within the matrix = osteocytes

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5
Q

What are osteoclasts?

A

reabsorbs bone
critical for repair and maintenance of bone
increases blood Ca levels
regulate hormones: parathyroid hormone, calcitonin and IL-6

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6
Q

What are osteocytes?

A

buried/trapped osteocytes

regulates bone matrix turnover

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7
Q

What is osteoid?

A

Bone cell before it has been mineralised

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8
Q

Explain the process on normal bone remodelling

A

Osteoclasts dissolve the collegen and reabsorb the bone
Osteoblasts lay down osteoids
Osteoids become mineralised = osteoblasts
some osteoblasts become trapped = osteocytes
cycle repeats

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9
Q

What are the 2 main biochemical marker of bone formation?

A

Alkaline phosphatase

Procollagen type I propeptides (P1NP)

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10
Q

What is the biochemical marker for bone degredation products of bone collagen?

A

Crosslinked telopeptides of type I collagen (NTX, CTX)

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11
Q

What are the 2 biochemical marker that are osteoclast enzymes?

A

Tartrate-resistant acid phosphatase (TRACP 5b)

Cathepsin K

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12
Q

Alkaline phosphatase (APA) is a marker for which two organs of the body?

A

Bone and liver

Specific isoenxymes can be measured when there is a diagnostic doubt

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13
Q

What does raised APA signify and in what conditions is it raised?

A

increased = increased bone remodelling/repair

Growing children
Fractures
Hyperparathyroidism - primary/secondary
Pagets disease of the bone

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14
Q

Why is P1PN a good marker and when does it increase?

A

Stable levels for a long time
do not need to fast the patient
increase = increased osteoblast activity

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15
Q

When does NTX and CTX increase?

A

Increase = periods of high turnover, crosslinking molecule that correlates highly with bone resorption
Hyperthyroidism, adolescents, menopause

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16
Q

What is DEXA imaging used for?

A

look at bone mass and density
small amount of radiation used
Lumbar spine/hip mostly imaged

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17
Q

What is a T score and what does it signify?

A

Amount of bone density - not age related
-1 and above = normal
Between -1 and -2.5 = osteopenia
-2.5 and below = osteoporosis

18
Q

What are the features of osteoporosis?

A

Inside the bone: thin cortex, plate compression, loss of trabecular network, wedge fractures, sclerosis
kyphosis
increased chest infections
bloating
ALP, P1PN normal as not sensitive enough, must be diagnosed via DEXA

19
Q

What are the risk factors for osteoporosis?

A 
female
age
smoker
alcohol
menopause
lack of absorption of nutrients e.g. ulcerative colitis/colonectomy
steriods
Vit D deficiency
20
Q

What is a fragility fracture?

A

fracture caused my a low force that wouldn’t normally affect bone
Common sites: spine, neck of femur, wrist

21
Q

What are examples of antiresrptive treatments? i.e. reduces bone breakdown

A

Bisphosphonates e.g. Alendronic acid

Denosumab

22
Q

What drug is an anabolic method of treating low bone density?

A

Terparatide - synthetic PTH

23
Q

What is bisphosphonates mechanism of action?

A

Similar structure to pyrophosphate
Inhibiting activation of enzymes that utilize pyrophosphate
Attach to Ca and accumulate on bone
Taken up by the osteoclasts

24
Q

What are the side effects of bisphosphonates?

A

poor absorption
difficult to take - must stay upright for a certain amount of time after taking it
oesophageal/upper GI problems
flu-like side effects
osteonecrosis of the jaw - necrosis/infection of jaw
atypical femur fracture

25
Q

What are the 2 catagories of bone metastases?

A

Lytic - destruction of normal bone

Sclerotic/Osteoblastic - deposition of new bone

26
Q

What are the features of a patient with metastatic compression of the spinal cord?

A 
Back pain - worse at night, gets better with movement initially
broken bones
numbness
Oliguria
Vomiting
loss of appetite
confusion
fatigue
anaemia
known to have cancer
Ca elevated
dehydrated/thirst
27
Q

What is checked in anyone with a high Ca level?

A

PTH

28
Q

What are the symptoms of hypercalcaemia?

A 
polyuria/polydipsia
mood disturbances
anorexia
nausea/vomiting
fatigue
constipation
abdo pain
coma
pancreatitis
dehydration
arrhythmias
29
Q

What cells in which part of the body secrete parathyroid hormone?

A

chief cells

parathyroid gland in neck

30
Q

How is parathyroid hormone regulated?

A

Low Ca → parathyroid gland releases PTH → decomposition of bone, increased Ca absorption from intestines, reabsorption of Ca from urine → increased Ca → negative feedback via Vit D

31
Q

What are Ca and PTH levels in primary, secondary, tertiary hyperparathyroidism?

A

Primary: ↑ Ca and PTH
Secondary: ↓ Ca, ↑PTH
Tertiary: ↑ Ca and PTH - happens after HPT has occurred chronically so PT forgets how to work

32
Q

What diseases can cause primary hyperparathyroidism?

A

Adenomas - can be ectopic
Carcinomas (rare)
Glandular hyperplasia - all 4 glands enlarged, usually genetic

33
Q

What are the clinical signs of primary hyperparathyroidism?

A

hypercalcaemia symptoms
renal disease - inc stones
Bone disease
muscle wasting

34
Q

What are the treatment options for primary hyperparathyroidism?

A

surgery

Calcimimetics - reduced PTH secretion

35
Q

What is Pagets disease of the bone and what are the signs and symptoms?

A

Rapid bone turnover and formation → abnormal remodelling = high ALP
arthritis
painful
fractures
Cranial nerves may be affected - hearing/vision loss
risk of osteosarcoma

36
Q

What investigations are used to detect Pagets disease?

A

Lab assessment
plain X ray
Nuclear medicine bone scan

37
Q

What is the treatment option for Pagets disease and how can it be monitored?

A

bisphosphonates

measure ALP and NTX

38
Q

What is osteomalacia?

A

Lack of mineralisation of the bone due to Vit D/phosphate/Ca deficiency
usually in children

39
Q

What are the clinical features of osteomalacia?

A

bone pain
muscle weakness
bone weakness
high ALP

40
Q

What would be the ALP, Ca, P and PTH levels for HyperPTH, Osteomalacia, Osteoporosis, Pagets and Bone metastasis?

A 
HyperPTH: ↑ ALP, ↑ Ca, ↓ P, ↑ PTH
Osteomalacia: ↑ ALP, Ca, ↓ P, PTH
Osteoporosis: all normal
Pagets: ↑ ALP, normal Ca, P and PTH
Bone Mets: ↑ ALP, ↑ Ca, normal P, ↓ PTH

CP (50 decks)

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