Pathophysiology of Osteoporosis Exam 1 Flashcards
Risk Factors for Osteoporosis and Osteoporotic Fractures
- Low bone mineral density (BMD)
- Advanced age >65
- Female sex
- Race / ethnicity (AA have lower risk)
- History of previous fragility fracture
- Osteoporotic fracture in a first-degree relative
- Postmenopausal
- Heavy alcohol consumption
- Cigarette smoking
- Low body weight (under 127 lbs)
- Predisposing medical conditions (ex. pts w/ RA)
- Predisposing medications
Medications Associated with for Osteoporosis and Osteoporotic Fractures
- Anticonvulsants
- Antiretrovirals
- Chemotherapy
- Glucocorticoids (e.g. > 5mg/d of prednisone for > 3 months)
- Heparin and LMWHs
- Medroxyprogesterone acetate injectable contraceptive
- Selective serotonin reuptake inhibitors
- Proton pump inhibitors
- Thiazolidinediones
What are the four steps in bone remodeling?
- Resorption
- Reversal
- Formation
- Quiescence (or Activation)
Resorption
Bone breakdown facilitated by osteoclast cells that resorb (dissolve) bone.
Reversal
Occurs when evacuation is complete and is the process of osteoclast undergoing apoptosis or moving to a new section.
Formation
Bone building process facilitated by osteoblast cells. Osteoblast ultimately become lining cells or become part of bone as osteocytes.
Quiescence (or Activation)
Rest period following bone formation.
Role of calcium in bone physiology
chief mineral component of the skeleton and is essential to the development and function of bone
Role of VitD in bone physiology
- modulate calcium and phosphate homeostasis
- Vitamin D undergoes hepatic conversion; then PTH stimulates its renal conversion to the active form of vitamin D, calcitriol
- calcitriol is promotes intestinal calcium absorption
Role of parathyroid hormone (PTH) in bone physiology
modulate calcium and phosphate homeostasis
Role of RANKL in bone physiology
major stimulus for hematopoietic stem cell differentiation necessary for development of mature osteoclasts
What are the categories of bone mass / osteoporosis from the World Health Organization (WHO)?
- Normal bone mass
- Low bone mass (AKA osteopenia)
- Osteoporosis
- Severe osteoporosis
What are the WHO values for normal bone mass?
T-score of -1 or higher
What are the WHO values for low bone mass (osteopenia)?
T-score between -1 and -2.5
What are the WHO values for osteoporosis?
T-score of -2.5 or lower
What are the WHO values for severe osteoporosis?
T-score of -2.5 or lower PLUS history of fragility fracture
Signs of Osteoporosis
- Deformity (i.e. dowager’s hump)
- shortened stature
- fracture
Symptoms of Osteoporosis
- Pain
- immobility
- depression
- low self-esteem
Risk factors for falls
- Prior fall / prone to falls
- Impaired vision or hearing
- Physical disability
- Environmental hazards
- Orthostatic hypotension
- Cognitive impairment
- Medications
Medications associated with falls
- Antidepressants
- Antihistamines
- Antihypertensives
- Antipsychotics
- Benzodiazepines
- Digoxin
- Diuretics
- Narcotic analgesics
- Laxatives
Which patients should undergo BMD testing?
- All women > 65 years of age
- Postmenopausal women < 65 years of age at increased risk for osteoporosis as determined by a formal risk assessment tool (i.e. SCORE, OST, or FRAX without BMD)
- Women and men with history of fragility fracture
- Some groups recommend screening for all men > 70 years of age and those 50-69 years of age at increased risk
- May consider re-testing every 2 years