Metabolic Bone Disease Flashcards
Define Osteoporosis
What is the T-score?
Reduced bone mineral density that increases risk of fractures and deformity; Common in elderly ladies after the menopause
- Comparing BMD with that of average 25yo female
- <-1 to >-2.5 is osteopaenia
- <-2.5 is OP
What risk factors for OP? (11)
What drugs can predispose to OP?
- Smoking, alcohol
- Low BMI
- FHx
- Drugs - see below
- Malabsorption
- Early menopause
- Liver/renal disease
- Endocrine disease - thyroid, cushings, DM, HyperPTH
- Inflm arthropathy
- Immobility/reduced activity
- Hypogonadism in males
Corticosteroids, Heparin, Anti-convulsants
Principles of management - lifestyle and falls
- Primary prevention of fractures!?
- Secondary prevention?
- Long term Steroids?
Scope vs Harm!!!
- Falls prevention (home assessment, protection); Lifestyle - reduce risk factors, diet etc, Ca, Vit D + medication i.e. Bisphosphonate
> 70 with # risk factors or T-score = Osteoporotic
2. 1#; Ca + Vit D
- > 75 - bisphosphonates
- 65-74 - DEXA scan and Bisp if T<-2.5
- <65 - Bis if <-3 or <-2.5 + risk factor
-
Treat if >65 or <65 and osteopaenic
i. e aim is to prevent fractures!!!
Medical treatment options in OP (7)
Calcium
Vitamin D
Bisphosphonates
Strontium
Calcitonin
teriparetide
Denosumab
Side effects and MOA
Calcium
Vit D
- GI disturbance, depression, polyuria etc. + risk of bradycardia; interaction with thiazides
- INcreaeses absorption of Ca from gut and decreases renal excretion
- Risk of vascular and organ calcificaiton; used in OP, CRF, osteomalacia, hyperpTH
Examples of bisphosphonates
Mechanism of action
Side-effects
Extra points
- Alendronate, Residronate, Zolendronate, Pamidronate
- Inhibit osteoclasts, thereby reducing bone resorption
- Bone pain, oesophagitis, nausea, diarrhoea
- Give once a week, on empty stomach at same time, sitting upright for at least 30 min after taking
Strontium ranelate
Indications
MOA
How give
Calcitonin
MOA
SE
- Postmenopausal OP
- Inc bone formation and reduces resorption
- At bedtime, 2 hours after any food or drink
- –| OC and reduces calcium and phosphate excretion by kidney
- In painful OP #
- Allergy, nausea, polyuria
Teriparetide - what is it and how works?
Denosumab - as above
- Synthesised rDNA for parathormone - therefore stim OB and inh OC - direct neew bone deposition
- Problem is Daily cost is massive and risk osteosarcoma - use if T <-4 and bisp don’t help
- MAb to RANK ligand - inh OC resorption; cost similar to branded bisp
Osteomalacia
Define
What predisposes?
How present?
What investigations and what possible long term consequence?
Impaired mineralisation of the osteoid matrix. This can cause skeletal deformitiy in the young, bone pain, aches, proximal muscle weakness and pathological #
reduced exposure to sunlight, malabsorption (e.g. Coeliac), poor diet –> can have Vit D deficiency or metabolic abnormality
Low PO4, Low calcium, High AlkP
Low vit D, High PTH (long term, may result in tertiary hyperPTH); x-rays may show pseudofractures (translucent bands at sites of stress)
How does high calcium present acutely?
What are two most common causes? Other causes?
Bones, stones, psychic groans and abdominal moans
Confusion, drowsiness, coma, muscle weakness, psychosis. Polyuria and polydypsia if less severe (nephrogenic diabetes insipidus). Anorexia, nausea and vomiting. Pain and constipation
Primary hyperPTH & malignancy e.g. Myeloma, mets(with bone tumour deposits, or rarely PTH-related peptide in lung SCC)
Other causes include: Thiazides, Lithium, SArcoid, Acromegaly, 3y hyperPTH, Addison’s, MEN, PAget’s
Hypercalcaemia Cont.
What Ix?
How Manage?
PTH levels
LFTs - elevated AlkP and other LFTS suggets malignancy
Isolated large rise in AlkP suggetss Paget’s
EP - paraprotein band in Myeloma
X-ray - hilar LA in Sarcoid; Frontal bossing and deformity in Paget’s (inc deafness)
Rehydrate, ? Loop diuretics, ? Bisphophonates, ? Steroids in malignancy or Calcitonin in Paget’s
Hypocalcaemia
Signs and symptoms?
2 Eponymous signs?
What is main cause? Pathology behind it? What is osteitis fibrosa cystica and how is it caused?
2 other causes
How treat acutely and in chronic disease?
Cicrumoral tingling, tetany, seizures.
Chvostek - tapping on facial nerve; Trousseau - infflate BP cuff –> carpopedal spasm
Secondary HyperPTH in renal failure
- No -OH vit D + retained phosphate cause Ca drop, leading to PTH release.
- OC activation, bone cysts and bone marrow fibrosis (osteitis fibrosa cystica) leading to renal bone disease – pepper pot skull and hand/spine changes
- WIll develop into tertiary if untreated (with Vit D and phosphate binders)
Post surgery, Osteomalacia
Acute - Calcium gluconate + ECG monitoring then ORal calcium + Vit D ASAP
Chronic - Vit D metabolites e.g. caclitriol, + calcium
What is Paget’s?
Investiagtions?
Disorder of bone remodelling typified by excessive bone resorption followed by innappropriate bone deposition and remoddelling. Specifically, repair stops at vascular osteoid, leading to weaker and more vascular bone.
Raised AlkP with normal calcium and phosphate
