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Flashcards in MSK - metabolic bone disease Deck (23):
1

list the common conditions that can lead to secondary osteoporosis

•Cushing’s syndrome or exogenous corticosteroids (eg > 5 mg/day for > 3 mths)
•Excessive alcohol use (> 2 units or 18 g/d)
•Smoking
•Malabsorption (coeliac, Inflammatory Bowel Disease)
•Primary or secondary hypogonadism
–e.g. associated with medications (corticosteroids, opioids, androgen deprivation therapy for prostate cancer, aromatase therapy for breast cancer)

Less common:
•Low BMI, high BMI (lack of/excessive exercise)

2

describe the clinical features of vitamin D deficiency and osteoporosis

• commonly asymptomatic
• height loss due to collapsed vertebrae
• fractures: most commonly in hip, vertebrae, humerus and wrist
-ƒƒ fragility fractures: fracture with fall from standing height
ƒƒ- Dowager’s hump: collapse fracture of vertebral bodies in mid-dorsal region
ƒƒ- x-ray: vertebral compression and crush fractures, wedge fractures, “codfishing” sign
(weakening of subchondral plates and expansion of intervertebral discs)

• pain, especially backache, associated with fractures

25-OH-Vitamin D level should only be measured after 3-4 mo of adequate supplementation and should not be repeated if an optimal level ≥75 nmol/L is achieved

3

interpret bone density tests (Z-score & T-score) tests and diagnose osteopenia or osteoporosis according to WHO criteria

Dual energy x-ray absorptiometry (DEXA): gold standard for measuring bone mineral density:
•Z-score: accounts for the patient's AGE, sex and ethnicity (

4

calculate absolute fracture risk

Multiple methods:
- FRAX by WHO
- Garvan Tool

FRAX includes:
- clinical risk factors, bone mineral density, and country-specific fracture and mortality data to quantify a patient's 10-year probability of a hip or major osteoporotic fracture.
- risk factors comprise of femoral neck bone mineral density, prior fractures, parental hip fracture history, age, gender, body mass index, ethnicity, smoking, alcohol use, glucocorticoid use, rheumatoid arthritis, and secondary osteoporosis.

FRAX was developed by the WHO to be applicable to both postmenopausal women and men aged 40 to 90 years

5

interpret radiological imaging tests to diagnose vertebral and other fractures

- lateral beak on XR suggests a stress fracture
- dual energy x-ray absorptiometry (DXA)
- BMT T-score
- Bone turnover markers: Resorption, serum b-CTX (bone resorption marker), Formation, P1NP (bone formation marker)

6

What are the preventative strategies used to prevent the onset of osteoporosis?

- Diet: Elemental calcium 1000-1200 mg/d; Vit D 1000 IU/d
- Exercise: 3x30 min weight-bearing exercises/wk
- Cessation of smoking, reduce caffeine intake
- Stop/avoid osteoporosis-inducing medications

7

describe the different therapeutic agents used to treat osteoporosis

- Hormone Replacement therapy (mostly women only). Limit factors stimulating bone resorption
- Raloxifene (women only)
- Bisphosphonates: inhibit osteoclast formation & increase osteoclast apoptosis
•Alendronate
•Risedronate
•Zoledronate

- Teriparatide
- Denosumab: binds to RankL
- (Strontium): activates osteoblast & inhibit osteoclast formation

8

explain how to monitor treatment responses to osteoporosis therapy and how to use second-line treatments for osteoporosis when first-line treatments fail

First line:
- Alendronate, Risedronate, Zoledronic acid (Bisphosphonate)
- Denosumab (RANKL inhibitors)
- Raloxifene (SERM for post-menopausal women)
- HRT (for post menopausal women)

Second line:
- Etidronate (bisphosphonate)
- Calcitonin (osteoclast receptor binding)

Monitor with:
beta-CTX, P1NP, BMD (bone mineral density)


If BMD increases to >T -2.5 at femoral neck after 3-5 years, a “drug holiday” can be considered, but only if the patient is monitored for any subsequent bone loss

9

How much height loss is significant?

>=3cm

Likely due to loss of height of vertebra(e) or intervertebral disc spaces

10

What are risk factors for osteoporosis?

•Low exercise levels
•Smoker (40 pack years)
•Co-morbidities (Rheumatoid arthritis etc)
•Poor nutrition, low calcium intake
•At risk of Vitamin D insufficiency/deficiency
•Prolonged amenorrhoea in younger years
•Post-meonpausal at age 50 y.o.

–previous fracture history
–family history of fracture/ osteoporosis
–No previous/current therapies for postmenopausal osteoporosis

11

What is P1NP in terms of bone health?

Bone formation marker
•Procollagen type 1 propeptides
•Cleared by liver endothelial cells

12

What is CTX in terms of bone health?

Bone resorption marker
•Cleaved during bone resorption
•Diurnal variation (8-9:30am)
•Fasting
•Cleared by kidneys

13

Choice of therapy in osteoporosis therapy in CKD

•Raloxifene (vertebral fracture risk protection only)
•Oral alendronate (weekly tablet)
•Oral risedronate (weekly or monthly tablet)
•Six monthly subcutaneous denosumab injections

Bisphosphonates must be used with hypocalcaemia precaution in CKD stage 4-5.

14

Describe some side effects of long term bisphosphonate therapy

- Atypical femoral fracture (with prolonged use)
- Osteonecrosis of the jaw (esp for IV bisphophonate)

15

List (5) causes of fractures in chronic kidney disease

1.Osteoporosis
2.Osteomalacia
3.Hyperparathyroidism
4.Adynamic bone disease
5.Post-transplantation (steroid, calcineurin inhibitors)

16

What are risks of fracture?

related to bone mineral density, age, history of previous fractures, steroid therapy

17

When is the diagnostic sensitivity of DEXA highest? (where do you have to measure)

when BMD measured at lumbar spine and proximal femur.

18

Compare osteoporosis vs. osteomalacia

Osteoporosis: Reduced amount of bone

OsteoMalacia: Normal amount of bone, but reduced Mineralization of normal osteoid

19

Appearance of osteoporosis on plain film

- ƒƒosteopenia: reduced bone density on plain films. may also be seen with osteomalacia, hyperparathyroidism, and disuse
-ƒƒ compression of vertebral bodies
ƒƒ- biconcave vertebral bodies (“codfish” vertebrae)
ƒƒ- long bones have appearance of thinned cortex and increased medullary cavity
-ƒƒ look for complications of osteoporosis: e.g. insufficiency fractures: hip, vertebrae, sacrum, pubic rami

20

Compare clinical pictures of osteomalacia, osteopenia & osteoporosis

Osteomalacia: Looser's fracture, bowing of long bone

Osteopaenia: decreased bone mass, but above threshold for osteoporosis

Osteoporosis: continuing vertebral compression, biconcave vertebral bodies

21

What are causes of primary osteoporosis?

• primary type 1: most common in post-menopausal women, due to decline in estrogen, worsens
with age

• primary type 2: occurs after age 75, seen in females and males at 2:1 ratio, possibly due to zinc
deficiency

22

What are (8) Clinical Signs of Fractures or Osteoporosis

• Height loss >3 cm (Sn 92%)
• Weight 5 cm (Sp 76%)
• Wall-occiput distance >0 cm
(Sp 87%)
• Rib-pelvis distance ≤2 finger breadth (Sn 88%)

23

Risk factors for bone disease

- low exercise levels
- smoker
- comorbidities e.g. RA
- poor nutrition, low calcium intake
- at risk of vitamin D insufficiency/deficiency
- prolonged amenorrhoea in younger years
- post menopausal

PMHx of fracture, FMHx of fracture/osteoporosis

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