Patho of Osteo, Paget and more Flashcards
Define osteopenia
Radiographically bone mass 1 to 2.5 standard deviasions below meak PEAK bone mass
Define osteoporosis
radiographically bone mass at least 2.5 standard deviations below mean peak bone mass
presence of atraumatic vertebral compression
localized disuse osteoporosis
generalized primary and secondary to a variety of conditions
Key forms of osteoporosis
Idiopathic
Postmenopausal
Senile
Define senile osteoporosis
bone density is reduced due to aging
define postmenopausal osteoporosis
bone density reduced due to lack of estrogen
decreased estrogen actually increases both bone resoption and formation - formation cannot keep up with resorption, net loss of bone
most bone loss within 5 years of onset
Fators effecting bone mass
Age: F>50 M>70 F>M Asian, White, Hispanic genetics gonadal steroids growth hormone timing of puberty calcium intake exercise
Key genetic factors for osteoporosis
Bone hoemeostasis pathway LRP5
RANKL, OPG, RANK
HLA locus unfluencing inflammation and calcium metabolism
varieant in Vit D receptor and signalling
Clinical manifestations of osteoporosis
Silent disease - loss without symptoms
present with bone pain and fracture in weight-bearing area
vertebral fractures in thoracic and lumbar
complications from fractures of femoral neck, pelvis, or spine
Detection of osteooporosis
Blood levels of calcium, phosphorus, PTH and alkaline phosphatase are normal
Eual-Energy X-ray Absorption scan (DEXA) wwith quatitiative computed tomography to measure bone density
Prevention of osteoprorsis
Starts in young adults
can regain density with:
wight-bearing exercises,
dietary Vit D and calcium (decrease with caffeine, alcohol, and smoking),
medicines to treat and prevent bone loss
Osteoporosis amenorrhea
Absence of regular menstrual cycle for three months or longer
3% young female
due to premature ovarian failure, excessive exercise, athletes, eating disorders, pituitary gland tumors.
Negatively affect peak bone mass and increase risk of osteoporosis
Paget’s disease overview
Disease of increased but organized and structurally unsound bone mass) clast and blast imbalance)
Etiology unknown: genetic link with 40% having it in the family. Environmental show signs of Paramyxoviridae within clasts. Measels and respiratory syncytial virus
Paget disease 3 phases
- osteolytic stage - uncontrolled osteoclast activity
- mixed osteoclast-blast stage - osteoblasts try to catch up
- Burn out quiescent osteoclastic stage - clasts burn out, osteoblasts continue to make bone but no remodeling by osteoclasts
Paget’s disease demographics
Late adulthood (>50)
M>F
3% of autopsies
More in people of English decent. Nonexistent in Scandanavia, Asia, Africa, and south Africa
Paget’s disease clinical manifestations
enlarged head - hat doesn’t fit
deafness
increased limb volume
increased warmth over bone
Paget’s disease lab results
Increased alkaline phosphatase due to osteoblast activity
Increased Urinary hydroxyproline due to collogen destruction
(Calcium, phosphate, PTH all normal)
Paget’s disease other symptoms
Fatigue
increased hat size
bone pain and deformity
pathological fracture
osteoarthritis secondary to bone deformity
nerve compression leading to deafness or blindness
increased risk of osteosarcoma (3x)
Paget’s disease recurrence
1/3 bone scan
1/3 biomarkers (increased ALP and urine hydroxyproline)
1/3 both
Rickets age and determining factors
children
deranged bone growth
Osteomalacia
Adults
remodeled bone is inadequately mineralized
osteopenia and factures
Vitamin D deficiency
Decreased sun exposure
poor diet
malabsorption
liver and renal failure
Rickets disease histological findings
palisades of cartilage are lost
Ricket’s presentation
Low vit D in children Pigeon breast deformity frontal bossing rachitic rosary craniotabes lumbar lordosis
Ostoemalacia presentation
Low vit d in adults
increased fractures due to weak bones
inadequate mineralization of osteoid in remodeled bone (weight-bearing bones in the vertebra and hips_)
abnormal labs: decreased serum calcium and phosphate. Increased PTH. Elevated alk phos
Osteomalacia histology
Trabecular bone covered in excessive amounts of osteoid
Parathyroid hormone role in bone formation
increased RANKL expression in osteoblasts leading to osteoclast activation and calcium mobilization
increase resorption of calcium by renal tubules
increased urinary excretion of phosphates
increased synthesis of active vit d
net elevation of serum calcium should inhibit PTH production
Hyperthyrodism and bone changes
Excessive or inappropriate levels of PTH
Stones, bones, moans, and groans
entire skeleton affected
fractures, bone deformation, joint problems
Hyperparathyroidism and bone morphology
osteoporosis
brown tumors - microfractures and secondary hemorrhages, influx of macrophages, reparative fibrous tissue
osteitis fibrosa cystica - combination bone cell activity, cystic brown tumors, peritrabecular fibrosis, severe hyperparathyroidism, rarely encountered now
Renal osteodystrophy
Skeletal changes in chronic renal disease
- osteopenia/porosis
- osteomalacia
- secondary hyperparathyroidism
- growth retardation
Renal osteodystrophy types
- high-turnover - increased bone resorption and bone formation with former predomination
- Low-turnover or aplastic disease - adynamic bone due to decreased osteoblast and clast activity
- Mixed pattern - areas of high turnover and areas of low turnover
