Metabolic Bone Diseases: 2 Flashcards
Calcitonin
- Which drug names are these? 2
- FDA approved for?
- Reduction of vertebral fractures by about ___% in persons with prior vertebral fracture
- Has not been shown to reduce what?
- Miacalcin or Fortical
- FDA approved for the treatment of osteoporosis in women ≥5 years post menopause
- 30% in persons with prior vertebral fracture
- Has not been shown to reduce nonvertebral fractures
Calcitonin
- MOA?
- Dose?
- CI?
- SE? 3
- Antagonizes the effects of PTH
- 200 IU as a single daily nasal spray or subcutaneous injection
- Contraindicated with history of allergy to salmon
- Side effects
- Rhinitis,
- epistaxis,
- allergic reactions
Hormone replacement therapy (HRT)
- When do we use this?
- What is this drug?
- How long is this therapy for?
- Only if failed other non-estrogen treatment options
- Prempro (estrogen/progesterone)
- 5 years of therapy
Risks with HRT therapy? 5
- ↑ risks of MI,
- CVA,
- invasive breast cancer,
- PE,
- DVT during 5 years of treatment
No MI risk if starting treatment within 10 years post menopause
Parathyroid hormone: Teriparatide (Forteo)
- How is this drug unique?
- When do we prescribe this?
- Such as? 2
- Unique in that it stimulates bone formation
- For severe osteoporosis when other treatments have failed
- continue to fracture 1 year after bisphosphonate therapy
- Intolerant to bisphosphonate therapy
Parathyroid hormone: Teriparatide (Forteo)
- Efficacy?
- Dose?
- Max duration on this?
- Monitor for what?
- ↓ risk of vertebral fx by 65%, ↓ nonvertebral fx by 53%
- 20mcg subcutaneous injection daily
- Max duration of therapy is 24 months
- Monitor for alterations in serum calcium
Parathyroid hormone: Teriparatide (Forteo)
SE? 4
Should avoid administration in pt’s at risk for osteosarcoma such as? 5
Side effects:
- leg cramps,
- nausea,
- dizziness
- increased incidence of osteosarcoma in animal studies
- Paget’s disease,
- prior radiation therapy of the skeleton,
- bone mets,
- hypercalcemia,
- hx of skeletal malignancy
Denosumab (Prolia)
- What is this?
- MOA?
- Indicated for?
- Used in who?
- Monoclonal antibody
- Decreases bone absorption by inhibiting osteoclast activity
- Indicated for postmenopausal women and men at high risk of fracture
- Used in cancer patients (breast and prostate)
How to follow pt’s on Rx therapy for osteoporosis
4
- Monitor for side effects
- Monitor for recurrent fractures
- Yearly height measurement
- Serial DXA scans- Baseline and every 2 years
Ongoing monitoring for OP? 2
- If lose 2 cm or more in height (0.8 in) or more in a year need repeat vertebral imaging to evaluate for new or additional vertebral fractures
- DXA scan at initiation of treatment and every 2 years
Treatment for special populations
4
- Glucocorticoid induced
- Renal failure
- Androgen deficiency
- Malabsorption
What do we have to change in renal dialysis patients with op?
Calcitriol to enhance calcium absorption
Other Metabolic Bone Diseases
? 4
- Paget Disease of the bone
- Osteomalacia
- Rickets
- Renal osteodystrophy
Whats the second most common metabolic bone disease?
Paget disease (Osteitis deformans)
Paget disease (Osteitis deformans)
- Describe how the lesions may be patterned?
- Most commonly involves what?
- What are the rest of the areas that are also commonly involved (in order of frequency?) 4
- Lesions may be solitary or occur at various sites
- Most commonly involves the axial skeleton
- Skull,
- thoracolumbar spine,
- pelvis,
- long bones of the lower extremity (in order of frequency)
Paget’s is a disease of the osteoclast
- Increased rate of?
- Overgrowth where?
- What kind of disorder?
- Possible _____ etiology?
- Onset after what age?
- Gender?
- Associated with?
- Increased rate of bone remodeling
- Overgrowth of bone at single or multiple sites
- Genetic disorder
- Possible viral etiology
- Onset after age 55
- Men > women
- Associated with osteosarcoma
Symptoms of Paget’s disease
- Arthritis
- Pain
- Bone deformity
- Fractures
- Radiculopathy
- Chronic back pain
- Impaired functional status
- Hearing loss
- Headache
- Vertigo
- Tinnitus
- Asymptomatic
Metabolic complications of Paget’s disease
- Hypercalciuria
2. Increased incidence of kidney stones
Labs for Paget’s? 3
- ↑ Serum alkaline phosphatase
- Serum calcium should be normal unless fracture or immobilization
- Serum phosphorus should be normal
Pagets
Imaging? 2
Xray
Bone scan
Paget’s
- What will you see on X-ray? 3
- What will you see on bone scan? 2
- Mixed lytic and sclerotic lesions
- Long bone bowing
- Bone thickening and enlargement
- Increased bone remodeling and
- blood flow
-More sensitive than x-ray early on
Paget’s Dx? 5
- History and physical
- X-rays
- Elevated serum alkaline phosphatase
- Baseline bone scan needed
- Baseline serum calcium, 25-OH Vit D, phosphorus
Paget’s Tx
- Goals? 2
- Tx? 2
- Goals:
- decrease pain,
- slow bone remodeling - Supportive treatment
- Vitamin D 800 IU, Calcium 1200 mg
- Bisphosphonates
Which biphosphanates for paget’s? 4
- Alendronate (Fosamax)(PO)
- Risedronate (Actonel) (PO)
- Pamidronate (IV)
- Zoledronic acid (IV)
Osteomalacia
- PP?
- How is the consistency of the bone?
- Caused by disorders that result in? 3
- Decreased mineralization of newly formed bone
- Bone is soft but no loss of bone matrix
- Caused by disorders that result in
- hypocalcemia,
- hypophosphatemia,
- or direct inhibition of the mineralization process
2 main causes of osteomalacia
- Insufficient calcium absorption from the intestine
2. Phosphate deficiency
Osteomalacia causes:
-Insufficient calcium absorption from the intestine? 3
-Phosphate deficiency? 2
- Lack of dietary calcium
- Vitamin D deficiency
- or resistance (chronic liver disease and kidney failure)
- Renal losses
- Decreased intestinal absorption
Etiology of osteomalacia?
5
1 Malabsorption
- Gastric bypass surgery
- Celiac sprue
- Chronic hepatic disease
- Chronic kidney disease
Symptoms of OM?
6
- Can be asymptomatic
- Bone pain and muscle weakness (94%)
- Bone tenderness (88%)
- Fracture (76%)
- Difficulty walking and waddling gait (24%)
- Muscle spasms, cramps, a positive Chvostek’s sign, tingling/numbness, or inability to ambulate(6-12%)
Work up for osteomalacia
Initial Lab eval? 7
- Serum calcium
- Phosphate
- Alkaline phosphatase
- 25-hydroxyvitamin D (25-OHD)
- PTH
- Electrolytes
- BUN and creatinine
Bone biopsy: OM
When may you need this?
May be needed if the diagnosis is in doubt or if the cause is unknown
Labs vary depending on cause. Results for nutritional deficiency:
- ↑ (2)
- ↓ (3)
↑ Alkaline phosphatase (95-100%)
↑ PTH elevated (100%)
↓Serum calcium and phosphorus (27-38%)
↓ Urinary calcium (87%)
↓ 25-hydroxyvitamin D (calcidiol) (
X-ray findings
for OM?
(most common 1)
5
- Most common finding : reduced bone density with thinning of the cortex
- Looser pseudofractures
- Fissures, or narrow radiolucent lines
- Loss of radiologic distinctness of the vertebral body trabeculae and
- concavity of the vertebral bodies (codfish vertebrae)
Looser’s zones (fractures)
- What are these?
- Usually at what angle to the involved cortex?
- Associated most frequently with what? 2
- What type of fx are these?
- Describe the margins?
- Cortical infarctions
- wide transverse lucencies traversing bone usually at right angles to the involved cortex
- Associated most frequently with osteomalacia and rickets
- Pseudofractures and considered a type of insufficiency fracture
- Sclerotic irregular margins and are often symmetrical
OM tx?
- Correct underlying cause
2. Vitamin D supplementation
OM vit D management considerations? 4
- 50,000 IU Q week X 6-8 weeks
- Followed by 800 IU daily
- Check serum and urine calcium at 1 mo, 3 mo, then Q 6-12 mo
- Check serum 25-OH-Vit D at 3-4 mo post initiation of therapy
OM
- Fx most commonly where? 2
- How is it different from OP?
- Why may the xray look like poor quality?
- What is a vitamin D metabolite and used for vitamin D replacement in renal and hepatic disease instead of Vit D2 or D3?
- Fractures most common in the
- distal radius and
- proximal femur - Not a significant cause of hip fractures like osteoporosis
- Loss of mineralization may make the x-ray image look poor quality
- Calcitriol
Rickets
- What is rickets?
- Rickets and osteomalacia usually occur together as long as what?
- After this?
- Deficient mineralization at the growth plate
- Rickets and osteomalacia usually occur together as long as the growth plates are open
- Only osteomalacia occurs after the growth plates have fused
Cause
of rickets? 3
- Decreased calcium
- Decreased vitamin D
- Renal phosphate wasting
Renal osteodystrophy
what is it?
Bone disease secondary to chronic kidney failure
Types of bone disease secondary to renal failure
4
- Osteitis fibrosa
- Mixed uremic osteodystrophy
- Osteomalacia
- Adynamic bone
Disorder of mineral and bone metabolism
5
- Calcium, phosphorus, vitamin D metabolism
PTH - Bone turnover
- Bone mineralization, volume, linear growth
- Bone strength
- Extraskeletal calcification also occurs
Secondary hyperparathyroidism is a major contributor
- How?
- Decreased what? 2
- Increased what? 1
- Reduced expression of what? 3
- Phosphate retention
- Decreased free ionized calcium
- Decreased 1,25 dihydroxyvitamin D
- Increase fibroblast growth factor
- Reduced expression of
- vitamin D receptors,
- calcium sensing receptors,
- fibroblast growth factor receptor
Summary of secondary hyperparathyroidism in CKD
- Starts when?
- Calcitriol deficiency and hyperphosphatemia = what?
- Hypocalcemia causes an increase in what?
- Starts when GFR below 60 ml/min
- Calcitriol deficiency and hyperphosphatemia = hypocalcemia
- Hypocalcemia causes an increase in PTH
Renal osteodystrophy: Define the following
- Osteitis fibrosis?
- Adynamic bone disease?
- Osteomalacia?
- Mixed uremic osteodystrophy?
- high turnover secondary to hyperparathyroidism
- low turnover, most common CKD related bone disease, due to suppression of the parathyroid glands
- low turnover with abn mineralization, not that common in CKD
- either high or low turnover and abnormal mineralization
Renal osteodystrophy Summary
- Disorders chracterized by? 3
- Tx aimed at?
- Basis of treatment for secondary hyperparathyroidism in CKD? 3
- Disorders characterized by
- bone turnover,
- mineralization
- volume - Treatment is aimed at the underlying problem
- Basis of treatment for secondary hyperparathyroidism in CKD
- Dietary restriction of phosphorus
- Supplemental active form of vitamin D (calcitriol)
- Phosphate binders