Osteomalacia Flashcards

1
Q

Define vitamin D deficiency and osteomalacia?

A

Osteomalacia is a metabolic bone disease characterised by incomplete mineralisation of the underlying mature organic bone matrix (osteoid) following growth plate closure in adults.

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2
Q

what is rickets?

A

disorder of defective mineralisation of cartilage in the epiphyseal growth plates of children

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3
Q

outline the aetiology of vitamin D deficiency?

A
  • 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
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4
Q

what are the causes of vitamin D deficiency?

A
  • 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
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5
Q

what are the symptoms of renal phosphate wasting?

A

low serum phosphate causes mylagia and weakness

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6
Q

what are the causes of renal phosphate wasting?

A
  • Fanconi syndrome
  • renal tubular acidosis ( type 2)
  • Hereditary hypophosphatemic rickets ( X linked or autosomal dominant)
  • Tumour induced osteomalacia ( Oncogenic hypophosphataemia ) raised tumour,
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7
Q

what is Fanconi’s syndrome?

A

GAP

  • phosphaturia
  • glycousria
  • amino aciduria
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8
Q

summarise the epidemiology of vitamin D deficiency and osteomalacia?

A

common in INUDSTRALISED COUNTRIES

more common in FEMLAES

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9
Q

what are the presenting symptoms of osteomalacia?

A
  • bone pain ( mainly in the axial skeleton) and tenderness
  • fractures esp femoral neck
  • proximal myopathy - waddling gait
  • weakness
  • malaise
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10
Q

what are the symptoms of rickets?

A
  • hypotonia
  • growth retardation
  • skeletal deformities
  • knock need, bowed leg
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11
Q

what are the signs of osteomalacia on physical examination?

A

o Bone tenderness

o Proximal muscle weakness

o Waddling gait

o Signs of hypocalcaemia- TROUSEA’S SIGN AND CHVOSTEK’S SIGN

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12
Q

what are the signs of hypocalcaemia on physical examination?

A

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
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13
Q

what are the signs of rickets on physical examination?

A
  • Bossing of frontal and parietal bones
  • Swelling of costochondral junctions (rickety rosary)
  • Bow legs in early childhood
  • ‘Knock knees’ in later childhood
  • Short stature
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14
Q

describe the radiograph in osteomalacia

A
  • 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)
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15
Q

describe bone biopsy after double tetracycline labelling?

A
  • 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
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16
Q

what are the appropriate investigations for vitamin D deficiency and osteomalacia?

A

BLOODS

  • low or normal Ca2+
  • low phosphate
  • High ALP
  • low 25-hydroxy vit D- except in vit D resistance
  • High PTH ( secondary hyperparathyroidism)
  • check U and Es
  • check ABG for renal tubular acidosis
  • increased phosphate excreting (in renal phosphate wasting)

( consider radiograph and bone biopsy after double tetracycline labelling)

17
Q

outline a management plan for vitamin D deficiency and osteomalacia?

A
  • Vit D and calcium replacement- if dietary deficient
  • in malabsorption/ hepatic disease- give Vit D2 ( ergocalciferol)
  • In renal disease or vit D resistance- give alfacalcidiol ( 1-hyrdoxyvitD3) or calcitriol ( 1,25-dihydroxyvitD3)

- monitor plasma calcium, initially weekly and if nausea and vomiting

  • also monitor serum calcium, phosphate, ALP, PTH, vit D
18
Q

what are the possible complications of vit D deficiency and osteomalacia?

A

Bone deformities

Hypocalcaemia can cause epileptic seizures

Cardiac arrhythmias

Hypocalcaemic tetany

Depression

Hypocalcaemia symptoms = CATs go NUMB

  • Convulsions
  • Arrhythmias
  • Tetany
  • NUMBness/paraesthesia
19
Q

How can you remeber the symptoms of hypocalcaemia?

A

CATs go NUMB

  • convulsions
  • arrythmias
  • tetany
  • numbness/ parasthesia
20
Q

summarise the prognosis for vit D deficiency and osteomalacia?

A

symptoms and radiological appearances improve with vit D treatment

done deformities in children tend to be permanent