CPT2: Osteoporosis Flashcards
What is osteoporosis?
•WHO definition:
“Osteoporosis is a disease characterized by low bone mass and structural deterioration of bone tissue, leading to bone fragility and an increased susceptibility to fractures of the hip, spine and wrist.”
Symptoms
- Asymptomatic – often remains undiagnosed until a fragility fracture occurs.
- Fragility fracture = a fracture that results from a mechanical force that would not ordinarily result in a fracture.
What are the cells involved in the pathophysiology of ostoeoporosis
Three different types of cell in bone:
- Osteoblasts
- Osteocytes
- Osteoclasts
What is the pathophysiology?
Osteoblasts are active bone forming cells and produce collagenase into the bone matrix. They secrete alkanline phosphatases which promotes deposition of calcium phosphate into the matrix to calcify bones
As the bone is formed and calcified osteoblasts become incoperated into the bone and transform into osteocytes which are relatively inactive bone cells
Osteoclasts are multi nucleated cells that cause bone resorption. They remove the bone matrix by phagocytosis and dissolve bone salts and release phosphate and calcium ions into the circulation
In osteoporosis there is increased osteoclast vs osteoblast activity. More osteoclates means more bone resportion and more calcium removed from bone to circulation causing bones to be brittle and fracture more easily
What are modifiable risk factors?
- Bone mineral density
- When reduced fractures more likely
- Influenced by envioment and genetics
- Low body weight
- Less bone tissues
- BMI less than 20 at risk. AIm between 20-25
- Smoking
- Slows osteoblasts works
- Lower body weight and women have earlier menopause
- Alcohol
- Increased falls likely
- Affects blasts and cytes
- Falls
- Physical inactivity
- Weight baring activity e.g. running and weight resistance exercise improve bone strength
What are non-modifable risk factors?
- Genes
- Age
- Chances increases with age
- Gender
- In women oestrogen maintains bone strength so once stopped increases risk
- Ethnicity
- Afro-carrabeans increased risk compaired to cauasians and asians
- Previous fractures
- Family history
- Co-morbidities
- Gi diseases
- COPD
- CKD
- Liver diseases
- Crohns disease (Ca+ malabsorption)
- Epilipsy
- Rheumatic diseases
- Endocrine disorders
Pharamcological risk factors
§Oral corticosteroids
§Selective serotonin-reuptake inhibitors (SSRIs)
§Anti-retroviral therapy
§Thyroid medication
§Proton-pump inhibitors (PPIs)
§Long-term Depo-Provera
§Anticonvulsants
§Aromatase inhibitors
§Gonadotropin-releasing hormone antagonists
§Anti-diabetic drugs – pioglitazone
Diagnosis
Bone mineral density (BMD) assessment:
- Gives a T-score: number of SD the BMD differs to young healthy individual
- Normal: T≥-1.0
- Osteopenia: -2.5<t>
</t><li>Osteoporosis: T≤-2.5</li><li>Established osteoporosis: T≤2.5 in the presence of ≥1 fragility fractures</li><li>DEXA scan is the most common way of measuring BMD – dual energy x-ray absorptiometry.</li>
</t>
https://qfracture.org/ (risk assessment which gives indication of how likely to suffer fracture in 10 years)
What does treatment aim to do?
Cue card also contains treatment plan
Reduce rate of bone turnover by targeting osetoclasts or increase bone formation by targeting oestoblasts
What is required for Calcium absorption?
Vit D
What is given to all patients with osteoporosis?
Recommended amounts per day:
- 700mg of calcium
- 10micrograms of vitamin D.
A number of combination products available, most containing 1g of calcium and 400units (10micrograms) of vitamin D but preparations differ.
Used widely in practice for all patients with osteoporosis.
What is first line treatment?
Bisphosphonates:
- Most commonly used are alendronic acid and risedronate.
- Mode of action: inhibit bone resorption. Increase BMD by altering osteoclast activation and function which is responsible for the breakdown of bone.
- Side-effects: upper GI effects, osteonecrosis of the jaw, osteonecrosis of external auditory canal, atypical femoral fractures.
- Interactions: food, calcium, antacids, oral medications can interfere with
Bisphosphonates:
- Cautions
- Contraindications
- MHRA warning
- Cautions: active GI bleeding, atypical femoral fractures, duodenitis, dysphagia, gastritis, gastric ulcer in last year, surgery of upper GI tract, symptomatic oesophageal disease, peptic ulcers, upper GI disorders.
- Contraindications: under 18 years old, pregnancy/breastfeeding, hypocalcaemia, abnormalities of oesophagus.
- MHRA warnings: atypical femoral fractures and osteonecrosis of the jaw and external auditory canal.
Counselling of patients taking bisphosphonates
•Counselling (oral preparations):
- Must be taken at least 30 minutes before the first food, drink or medication of the day with a full glass of water.
- Must be taken upon arising for the day whilst in upright position.
- Swallow the tablet whole – do not crush or chew.
- Do not lie down for at least 30 minutes after taking.
- Should not be taken at bedtime or before arising for the day.
- Weekly dosing.
- As bisphosphnates interact with Calcium supplements advise to miss calcium supplement on day of bisphosphonate
- Dental check up require prior to start and also need to remind patients to keep good oral hygeine and attend regular dental checkups. Report any dental mobility, swelling, pain, discharge or nodule sores to dentesist or doctor
- How does alendronic acid work
- Dose?
- Renal function dose?
Alendronic acid:
- Nitrogen-containing bisphosphonate which inhibits osteoclastic bone resorption with no direct effect on bone formation.
- 70mg once a week.
- Avoid if GFR is <35mL/min.
