Osteomalacia Flashcards
Define vitamin D deficiency and osteomalacia?
Osteomalacia is a metabolic bone disease characterised by incomplete mineralisation of the underlying mature organic bone matrix (osteoid) following growth plate closure in adults.
what is rickets?
disorder of defective mineralisation of cartilage in the epiphyseal growth plates of children
outline the aetiology of vitamin D deficiency?
- vitamin D deficiency
- renal osteodystrophy- cause 1,25-dihydroxycholecalciferol deficiency
- drug induced-anticonvulsants may induce liver enzymes causing increased breakdownof 25hydroxyvitD
- Renal phosphate wasting - syndrome in which there excess urinary phosphat loss
what are the causes of vitamin D deficiency?
- lack of exposure to sunlights
- dietary deficiency
- malabsorption
- decrease 25 hydroxylation of vitamin D ( due to liver disease, anticonvulsants)
- decrease 1 alpha- hydroxylation of vitamin D ( due to chronic kidney disease, hypoparathyroidism)
- vitamin D resistance
what are the symptoms of renal phosphate wasting?
low serum phosphate causes mylagia and weakness
what are the causes of renal phosphate wasting?
- Fanconi syndrome
- renal tubular acidosis ( type 2)
- Hereditary hypophosphatemic rickets ( X linked or autosomal dominant)
- Tumour induced osteomalacia ( Oncogenic hypophosphataemia ) raised tumour,
what is Fanconi’s syndrome?
GAP
- phosphaturia
- glycousria
- amino aciduria
summarise the epidemiology of vitamin D deficiency and osteomalacia?
common in INUDSTRALISED COUNTRIES
more common in FEMLAES
what are the presenting symptoms of osteomalacia?
- bone pain ( mainly in the axial skeleton) and tenderness
- fractures esp femoral neck
- proximal myopathy - waddling gait
- weakness
- malaise
what are the symptoms of rickets?
- hypotonia
- growth retardation
- skeletal deformities
- knock need, bowed leg
what are the signs of osteomalacia on physical examination?
o Bone tenderness
o Proximal muscle weakness
o Waddling gait
o Signs of hypocalcaemia- TROUSEA’S SIGN AND CHVOSTEK’S SIGN
what are the signs of hypocalcaemia on physical examination?
Trousseau’s sign
- inflation of a blood pressure cuff to above the systolic pressure for > 3 mins causes tetanic spasm of the wrist and fingers
Chvostek’s sign
- tapping over the facial nerve causes twitching of the ipsilateral facial muscles
what are the signs of rickets on physical examination?
- Bossing of frontal and parietal bones
- Swelling of costochondral junctions (rickety rosary)
- Bow legs in early childhood
- ‘Knock knees’ in later childhood
- Short stature
describe the radiograph in osteomalacia
- May appear normal
- May show osteopaenia
- Looser’s zones = wide, transverse lucencies traversing part way through a bone, usually at right angles to the involved cortex and are associated most frequently with osteomalacia and rickets (AKA pseudofractures)
describe bone biopsy after double tetracycline labelling?
- tetracycline is deposited at the mineralisation front as a band
- after 2 course of tetracycline ( separated by a few days)- distance between bands of deposited tetracycline is reduced in osteomalacia- incomplete mineralisation
