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
