Osteoporosis Flashcards
Osteoporosis
- Deficient matrix
* Normal mineralisation
Osteomalacia
- Normal matrix
* Deficient mineralisation
Hyperparathyroidism
- Normal matrix and mineralisation
* Increased Resorption
Parathyroid hormone and bones
Parathyroid hormone regulates calcium levels in the blood, largely by increasing the levels when they are too low. It does this through its actions on the kidneys, bones and intestine:
Bones - Parathyroid hormone stimulates the release of calcium from large calcium stores in the bones into the bloodstream. This increases bone destruction and decreases the formation of new bone.
Thyroid hormones and bones
Hyperthyroidism is a condition where the thyroid gland produces too much thyroxine.
In adults, overt hyperthyroidism leads to acceleration of bone turnover and loss of mineral density in 10-20%, mainly in cortical bone. If the amount of new
bone produced can’t keep pace with the amount broken down,the bones can gradually become weaker. If the cause of the hyperthyroidism is not treated and thyroxine levels stay high fora long time, the risk of developing osteoporosis increases.
Cortisol and bones
- In times of high stress the body will break down amino acids to form glucose through the process of gluconeogenesis. Cortisol is the major stress hormone that catalyzes this process. Collagen is one of the target areas for spare amino acids. Chronically elevated stress levels increases collagen breakdown.
- Cortisol primarily acts on the outer layer of the bone called the periosteum. Research has shown that elevated cortisol inhibits osteoblast formation and cell proliferation.
Define osteoporosis
A generalised, progressive diminution in bone tissue mass per unit volume of bone (ie density).
The ratio of mineral to organic elements (ie matrix) is unchanged in the remaining morphologically normal bone
Osteoporosis scan results
Osteoporosis is a bone mineral density 2.5 standard deviations below peak bone mass (20-year-old sex-matched healthy person average) as measured by a (DEXA Scan) - Bone density scan
Osteoporosis Etiology
An outcome secondary to a number of pathological processes. Osteoporosis is caused a group of diseases which have a Final Common Pathway
Osteoporsis Histology
Pathological changes: •Reduced cortical thickness •Reduced number of trabeculae •Reduced size of trabeculae •Normal chemical composition •Normal mineralisation
Classifications of osteoperosis
- Generalised (diffuse)
* Localised (regional)
Generalised Osteoporosis causes?
- Genetic (congenital)
- Deficiency States
- Neoplastic
- Iatrogenic
Osteoporosis genetic causes:
-Genetic (congenital)
•Osteogenesis imperfecta
•Anaemias
Osteoporosis deficiency states:
-Deficiency States •Scurvy •Malnutrition •Anorexia nervosa •Protein deficiency •Alcoholism •Liver disease
Osteoporosis Neoplastic causes:
-Neoplastic •Myeloma •Leukemia •Lymphoma •Metastatic disease
Osteoporosis Iatrogenic causes:
-Iatrogenic causes
•Heparin-induced
•Dilantin-induced
•Steroid-induced
Osteoporosis Miscellaneous causes:
- Involutional (senescent)
- Postmenopausal
- Amyloidosis
- Ochronosis
- Paraplegia
- Weightlessness
- Idiopathic etc
Generalised Osteoporosis Classification:
- Primary
- Secondary
Primary Osteoporosis Primary
- Type I (Postmenopausal)
- Type II (Involutional)
- Idiopathic
Primary Osteoporosis Primary Type 1 (Postmenopausal)
Age group:
-51-75 years
Type of bone:
-cancellous (spongy or Trabecular)) bone
Main manifestation:
- vertebral crush fractures
- Distal radial fracture (colle’s)
Probable cause: Postmenopausal endocrine changes
Primary Osteoporosis Primary Type 2 (Involutional)
Demographic:
- >70 years - x2 females - Gradual Onset - Age related
Type of Bone:
-Trabecular and cortical loss
Main manifestation:
-Bone fracture: (Femoral neck, proximal humerus, proximal tibias, pelvic and vertebra)
Probable cause:
- Age related decrease in Vitamin D synthesis
- Age related resistance in Vitamin D activity
**Type 1 and 2 may coexist in females
Involution Define
The progressive degeneration occurring naturally with age, resulting in shrivelling of organs or tissues
Secondary Osteoporosis
- Account for less than 5%
- Idiopathic and probably multifactor
-Causes:
•Endocrine causes: hyperparathyroid, hyperthyroid, cortisol (cushings), testosterone, diabetes
•Drug induced: cortisone, ethanol, tobacco
•Miscellaneous: prolonged immobilisation, chronic renal failure, RA
SSX of osteoporosis
- Usually asymptomatic
- May have aching bone pain especially in the back
Complications of osteoporosis
Fractures are the main source of symptoms:
•Typically vertebral crush fractures
•Minimal or no trauma required
•Typical site: T8 and below
•Non-vertebral fractures are usually secondary to falls
Vertebral crush fracture, clinical manifestation:
- acute pain (non radiating)
- aggravation of pain by weight bearing
- ± local tenderness
- subsides within days to weeks
Clinical manifestations if multiple fractures:
- Dorsal kyphosis
* Dull arching pain due to abnormal stress on spinal muscles & ligaments
Laboratory Manifestations of types primary and secondary osteopathy:
Serum Ca: Normal in primary osteoporosis
Serum P: Normal in primary osteoporosis
ESR: Normal in primary osteoporosis
Serum Alk Phosphate: Increased in fractures
PTH: Decreased in type 1 osteoporosis; increased in type 2
Hypercalciuria: occurs in 20% of post menopausal osteoporotic women.
Radiological Findings:
- Decreased radiodensity (need >30% bone loss) Xray
- Prominence of cortical end plates (subjected to increased forces)
- Loss of horizontally oriented trabeculae
- Wedge fractures
Osteoporosis Treatment
- Increased calcium intake before age of 20
- Increased weight-bearing exercise.
Osteoporosis diagnosis
three methods:
- Radiographic and Ultrasonic measurement of bone density
- Laboratory biochemical markers
- Bone biopsy with pathologic assessment
Osteoporosis Risk Factors
- Female
- Premature menopause/Postmenopausal
- Caucasian
- > 65 years
- Thin women, with small bone structure
- Family history of osteoporosis
- Sedentary life style
- Cigarette smoking (↓ed ability to absorb Ca2+)
- Alcohol abuse (poor nutrition + ↑ed risk of falling)
- Low calcium intake
- High caffeine consumption
Calcium Dietary
- Dairy products: Low/Non fat milk, cheese, & yoghurt
- Dark green leafy vegetables: bok choy and broccoli
- Calcium fortified foodsorange juice, cereal, bread, soy beverages, & tofu products
- Nuts: almonds
