Osteoporosis Flashcards
MSK
Definition & Causes
Osteoporosis is a reduction in actual bone mass. = more fractures and broken bones
Osteopenia is a reduction in the mineral content of bone
CAUSES
*Postmenopausal oestrogen deficiency
*Age-related deterioration in bone homeostasis
*Long term levothyroxine use. Subclinical hyperthyroidism may be associated with bone loss. To minimise the risk of osteoporosis, dosage of levo should be titrated to the lowest possible effective.
*Prolonged glucocorticoid use
*Myeloma (a type of cancer that develops from cells in the bone marrow)
Treatments
Combination of lifestyle changes + drug treatment
- aims to prevent fragility fractures in patients.
NON Pharmacological
Increase physical activity
Stop smoking
Maintain normal BMI (20–25 kg/m²)
Reduce alcohol intake (improves bone health and reduces risk of fracture)
Good intake of calcium and VIT D
Calcium through diet or supplements if needed. (Seeds, cheese, yoghurt, salmon, beans/lentils, almonds, etc)
Vit D can be through diet too if needed (Oily fish, sardines, salmon, egg yolk, red meat, liver)
Pharmacological
Low risk = no drugs
Medium/High = T score is <-2.5 (osteoporosis range) offer bone sparing drugs treatment.
T score >-2.5 - modify risk factors and treat conditions then repeat DXA when appropriate.
1ST LINE =
Bisphosphonate = alendronate 10 mg OD or 70 mg OW, or risedronate 5 mg OD or 35 mg OW.
- OD is men only.
Contraindicated = ALT - referral
- If Adequate calcium intake (700mg/day) = 10mcg of VIT D daily PT with less sunlight
- If Poor calcium intake = 10mcg VIT D + 1g Calcium daily
OR 20mcg VIT D + 1g calcium daily for elderly/ living in nursing home.
Consider HRT to younger post menopausal women
Post menopausal women
1st line is same.
ALT oral ibradronic acid or parenteral denosumab
Bisphosphonate ALT = raloxifene or strontium.
Extra ALT HRT (Tibolone)
SEVERE or high risk of fracture = teriparatide or romosozumab
Glucocorticoid induced osteoporosis
Glucocorti can cause bone loss and increased risk of fractures.
- Greatest rate of bone loss happens in early treatment
Prophylaxis and treatment same as Post menopausal except HRT.
MHRA Bisphosphonates (EXAM Q)
Sit/Stand upright for 30 min after eating meds. Also take 30 min b4 breakfast with plenty of water.
PT taking >2yrs:
- Atypical femoral fracture report signs of thigh hip or groin pain
- Osteonecrosis of jaw (less blood to jaw bone) - Good oral hygiene, routine dental check ups risk higher in IV
- Osteonecrosis in external auditory canal - Report ear pain, discharge, or ear infection
STOP, seek advice if - Dysphagia, new or worsening heart burn, pain on swallowing
Bone remodelling EXTRA
Bone is constantly remodelled.
Balance of reabsorption and formation.
Osteoclasts are cells that reabsorb bone by “digging” pits, while osteoblasts secrete bone matrix into these pits, called osteoid. Osteoid is then mineralised, resulting in calcium phosphate crystals being deposited.
Drugs and MOAs (EXTRA)
HRT - oestrogen replacement - effective but this is not selective, which means it can have effects on many body systems.
SERMs - (Raloxifene) - binds to oestrogen receptors agonist on some tissues, antagonist on others
Mechanisms include:
* Increased osteoblast activity in a dose-dependent manner,
* Reduced activity of osteoclasts.
* extensive first-pass metabolism, well distributed around the body.
PTH and PTH fragments - teriparatide): Increase bone mass by paradoxically stimulating osteoblast numbers and decreasing osteoblast apoptosis. They act on PTH-1 receptors (GPCR), activating adenylate cyclase, PLA2, PLC and raise intracellular Ca2+ levels. These are given subcutaneously
Bisphosphonates (alendronate and risedronate): These act on osteoclasts to promote their apoptosis, inhibiting bone reabsorption. Usually given orally and accumulate at site of bone mineralisation.
Absorption can be impaired by certain foodstuffs, especially milk, and these drugs can cause severe GI disturbances. Remain upright after taking for 30 mins, ensure drug has passed into the stomach so as to minimise ulceration of the trachea
Calcium in the bones EXTRA
Bone is made from Ca, Phosphate, protein meshwork.
Serum Ca2+ ion concentration is controlled by parathyroid hormone (PTH) secreted from the parathyroid glands found behind the thyroid gland in the neck.
PTH is secreted in response to low serum Ca2+ ion levels. It acts on the kidneys to reabsorb Ca2+ ions and to stimulate the activation of vitamin D. This fat-soluble vit D is obtained from sun exposure certain foods, and supplements but is biologically inert must be activated. Activated vit D promotes absorption of dietary Ca2+.
PTH also acts directly on bone to mobilize Ca2+ (transfer Ca2+ from bone to the blood).
Calcitonin, secreted from parafollicular cells (also known as C cells) in the thyroid gland, inhibits calcium mobilisation from bone and also decreases reabsorption from the renal tubule.
