Osteomalacia Flashcards
Define osteomalacia
A metabolic bone disease that occurs in adults (after growth plate fusion) and is characterised by insufficient osteoid mineralisation.
‘soft bones’
What is the relevant epidemiology of osteomalacia?
Incidence = 100 per 100,000 person years
Peak incidence between 50-60yrs
Equal between sex
What are some risk factors for osteomalacia?
Older age (over 65yrs)
Darker skin pigmentation
Obesity
Cover skin for religious, health or cultural reasons
Housebound or care home
Malabsoprtion due to GIT disorder or weight loss surgery
End stage CKD
Severe liver cirrhosis
Vegetarian or vegan diets
Medications increasing risk of Vitamin D deficiency (antacids, carbamezepine, orlistat)
What is the aetiology of osteomalacia?
- Vitamin D deficiency (dietary, absoprtion or sunlight).
- Related to medication - antiepileptic, corticosteroids, rifampicin and thiazide diuretics
- Ineffective VD metabolism - CKD or liver cirrhosis
What is the basic pathophysiology of osteomalacia?
Chronic vitamin D or phosphate deficiency leafs to osteoclastic destruction of bone to maintain serum calcium levels.
Resorbed bone is replaced with unmineralised osteoid and bone mineral density decreases as a result.
What are the key MSK/skeletal symptoms of osteomalacia?
MSK: Bony pain worse when weight bearing norm in lower back, hips, pelvis and lower legs.
Muscle weakness - proximal
Joint pain - large joints due to periarticular calcification
Fractures - insufficiency fractures
Skeletal: pseudofractures (radiolucent bands traversing bone that represent unmineralised osteoid), bowing deformities, spinal deformities (vertebral compression kyphosis or scoliosis)
What are the key neuro/extra-skeletal symptoms of osteomalacia?
Paresthesia - numbness of tingling in extremities due to hypocalcemia
Tetany - facial muscle switching
Dental abnormalities - loss of dentin - periodontal disease, loss of enamel
Nonspecific symptoms: fatigue, anorexia, weight loss
How might a patient with osteomalacia present on examination?
Waddling gait
Bowed legs
Proximal muscle weakness
Generalised bone and joint tenderness
Signs of hypocalcemia (tetany, carpopedal spasm)
Spinal deformities - kyphoscoliois
What are some differentials to osteomalacia?
Rickets - children
Primary hyperPTH - excessive Ca2+, bony pain, pathological fractures, muscle weakness and fatigue, constipation, depression
Bony mets - bony pain, pathological fractures
Renal osteodystrophy - background CKD
Osteoporosis - decrease bone mass,
Pagets disease of bone -
Hypothyroidism
Polymyalgia rheumatica -
What investigations should be done for osteomalacia?
Bedside: urinalysis (proteinuria for CKD), reduced urine calcium, 24hr urinary phosphate for wasting
Bloods: VitD, bone profile (calcium, phosphate, ALP), PTH (raised), U&Es (CKD), LFT (liver failure) FBC (anaemia in malabsoprtion), Ferritin, B12, FOlate for other deficieines, TFT (Diff).
Imaging - DEXA (bone density), Bone x-ray (insufficiency fracture and pseudofractures), demineralised bone - fuzzy appearance
What is the typical management for osteomalacia?
Underlying cause investigation and management
Lifestyle on diet (VitD and calcium) and sun exposure.
Vitamin D supplements
Calcium supplements if needed
Should be followed up to ensure normalised
How should vitamin D supplements be prescribed?
Norm - calciferol
If CKD - alfacalcidol
Initial loading dosee 300,000 IU over 6-10w
Maintenance 800-2,000 IU per day onwards.
What are the different levels of vitamin D in the body?
Sufficient = calcidoil of greater than 50nmol/L
Insufficient = between 25-50nmol/L
Deficient = less than 25nmol/L
