metabolic bone dz Flashcards
(34 cards)
RANK
receptor on osteoclasts which facilitates bone resorption when RANK-L binds to it.
OPG
osteoprotegerin- a decoy RANK-L receptor which decreases bone resorption
Risk factors for fragility fractures of osteoporosis
Previous Fractures, Age (increases after 55), Falls, Low Bone Mass
How do vertebral fractures affect fracture risk
Increases risk by 5% of having another fracture
compare osteoporosis vs osteopenia
Osteopenia: Bone mineral density T score of -1 to -2.5 Osteoporosis: bone mideral density T score of < -2.5. Normal: BMD T score of >-1.0
normal bone remodeling
Resorption= formation, OC= OB, old bone = new bone. Bone mass remains stable
Non-modifiable risk factors for low bone mass
Age, Race, Gender, Family History, Early Menopause
Modifiable risk factors for low bone mass
Low Calcium Intake, Low Vitamin D Intake, Estrogen Deficiency, Sedentary Lifestyle, Cigarette Smoking, Excess Alcohol (> 2/day), Excess Caffeine (> 2/day), Medications
How is diagnosis of osteoporosis/osteopenia made
measure bone density at and base T score on lowest density site
Who is treated for osteoporosis
Anyone with a fragility fracture, vertebral fracture, hip fracture or T score 3% risk of hip fracture of >20% major OP fracture
Osteoporosis prevention and treatment
- Ca- 1000-1500mg/day. Supplement if dairy intake insufficient. 2. Vitamin D. 3. exercise- aerobic and resistance. 4. falls- assess and prevent
osteoporosis treatment
- anti-resorptive agents: bisphosphanates, denosumab, raloxifene, calcitonin, estrogens. 2. anabolic agents: teriparatide, romosozumab
Define osteomalacia
impaired bone mineralization due to inadequate Ca and Phosphate resulting in soft, weak bones. Called rickets in kids
Causes of osteomalacia and rickets
- Vitamin D deficiencies- poor intake/sunlight, renal dz, hypoparathyroidism, congenital. 2. phosphate disorders- poor intak, renal phosphate wasting, congenital (Vitamin D resistant rickets- impaired Vit D formation or renal phosphate wasting)
clinical features of osteomalacia and rickets
osteomalacia: pain, deformities, fractures. Rickets: pain, deformities, muscle weakness, short stature
Osteomalacia/rickets labs
Decreased Ca, decreased phosphate, increased serum alkaline phosphatase, increased serum PTH, decreased urine Ca
osteomalacia radiology
fractures, pseudofractures- milkmans fractures, loosers lines
rickets radiology
Bowing of long bones, flaring ends of long bones, delayed epiphyseal calcification
osteomalacia/rickets treatment
- Nutritional Vitamin D Deficiency- Vitamin D and Calcium. 2. Congenital 1 Alpha Hydroxylase Deficiency- Calcitriol and Calcium. 3. Congenital Vitamin D Receptor Deficiency- High Dose Vitamin D or Calcitriol and Calcium. 4. Congenital Hypophosphatemic Rickets- Calcitriol and Phosphate
Define pagets
An Idiopathic Bone Condition Characterized by Excessive/Unregulated Bone Resorption and Formation
Etiology of pagets disease
genetic component (enhances osteoclast formation/reactivity) plus chronic paramyxovirus infection (induces changes in osteoclast precursors)
Gene linked to Pagets disease
Sequestosome I/ p26- a ubiquitin binding protein that induces NF-kB activation and osteoclast differentiation/activity/survival.
Clues to the viral cause of pagets disease
it is associated with dog owners, specific locations (rare in africa/asia), osteoclasts show paramyxovirus-like inclusions in nuclei + cytoplasm.
Pagets disease skeletal features
pain, deformity, fractures, osteoarthritis, hypervascularity, acetabular protrusion, osteogenic sarcoma. Commonly involves pelvis, skull, vertebrae, femur and tibia
