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Rheumatology > Osteomalacia, Rickets, Osteogenesis Imperfecta and Pagets Disease > Flashcards

Osteomalacia, Rickets, Osteogenesis Imperfecta and Pagets Disease Flashcards

1
Q

What is Osteomalacia?

A

Deficiency of Vitamin D in adults, resulting in the accumulation of osteoid and poor mineralisation. It differs from rickets in that it occurs after growth has ceased

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2
Q

What is the pathogenesis of osteomalacia?

A

Defective mineralization of newly formed bone matrix or osteoid due to vitamin D deficiency, especially in individuals living in temperate regions who keep large parts of the skin covered throughout the year.

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3
Q

What is the most common cause of Osteomalacia?

A

Most common cause is hypophosphataemia due to hyperparathyroidism 2o to vitamin D deficiency.

Most common cause of vitamin D deficiency worldwide is dietary deficiency/malabsorptionn

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4
Q

What are other causes of osteomalacia, besides HPTH 2o to Vit D deficiency?

A
  • Hypovitaminosis D
  • Malabsorption
  • Renal disease
  • Other
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5
Q

What are the symptoms of osteomalacia?

A

Can be asymptomatic

  • Widespread Bone pain
  • Proximal myopathy (with normal CK)
  • Fragility fractures
  • Polyarthralgia
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6
Q

What is the differential diagnosis for osteomalacia?

A
  • Osteoporosis
  • Fibromyalgia
  • Polymyalgia rheumatica
  • Polymyositis
  • Rheumatoid arthritis
  • Multiple myeloma
  • Metastatic bone disease
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7
Q

What bloods would you do to investigate for osteomalacia?

A
  • Serum alk phos - elevated in 90% of cases.
  • Serum Ca2+ and PO43- - normal or decreased
  • Serum PTH - elevated
  • Serum 25-(OH)D3 - decreased
  • Serum FGF-23 - elevated - tumour-induced osteomalacia.
  • U+Es - Renal failure
  • Serum ferritin - Signs of malabsorption
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8
Q

What imaging would you do to investigate for osteomalacia?

A
  • X-Ray
  • Tetracycline-labelled bone biopsy - GOLD STANDARD TEST, however only used in research as it is not practical in a clinical setting
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9
Q

How would you treat someone with osteomalacia?

A
  • Vit D3 supplementation - dietary insufficiency
  • Parenteral Calcitriol - Malabsorption or hepatic disease
  • Alfacalcidol - in renal disease
  • Monitor Ca2+
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10
Q

What is Rickets?

A

Rickets is defective mineralization at the epiphyseal growth plate and is found in association with osteomalacia in children. The classic presentation is due to interference with the growth plate.

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11
Q

What are the clinical features of rickets?

A
  • Growth Retardation
  • Hypotonia
  • Genu varus/valgus
  • Features of Ca2+ deficiency
  • Myopathy
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13
Q

What is Pagets Disease and how does it occur?

A

“Osteitis deformans” - focal disorder of bone remodelling.

Disturbed bone remodelling

  • Excessive bone resorption followed by the rapid laying down of disorganized, weak, abnormal bone.
  • There is also increased local bone blood flow and fibrous tissue in adjacent bone marrow. Ultimately, formation exceeds resorption but the new bone is structurally abnormal.

Outcome - Bigger, less compact, more vascular and brittle bone

BIG, BENT, BLOODY, BASTARDS!!!

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14
Q

What are the clinical feautures of pagets disease?

A

70% asymptomatic

  • Bone pain - Deep, boring in nature
  • Hearing loss
  • Bony deformity
  • Osteoarthritis
  • Pathological fractures
  • Headache
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15
Q

What are risk factors for developing Pagets Disease?

A
  • Age
  • Temperate climates (not sure why??)
  • Anglo-saxon heritage
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17
Q

What are the complications of Pagets Disease?

A
  • Pathological Fractures
  • Osteoarthritis
  • Hypercalcaemia
  • Nerve compression
  • Osteosarcoma
  • High-output CCF - if >40% skeleton involved
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18
Q

What bloods can be done to investigate for Pagets?

A
  • Ca2+ and PO43- - normal
  • Alk phosphatase - markedly increased (ISOLATED)
  • PTH - Normal
  • 25-OH Vit D - normal
  • 1,25-OH2 Vit D - normal
19
Q

What imaging could be done to investigate for Pagets Disease?

A

X-rays

  • Localised bone enlargement
  • Patchy cortical thickening
  • Sclerosis, osteolysis and deformity
  • Affinity for axial skeleton, long bones and skull

Bone Scan

  • “Hot spots”

Scan weight bearing areas for occult fractures

20
Q

How does Osteogenesis Imperfecta present?

A
  • Fragility Fractures
  • Blue tinged sclera
  • Short Stature
  • Hypermobility
  • Hearing loss
  • Breathing Problems
  • Dental problems
21
Q

How would you manage someone with Pagets Disease?

A
  • Bisphosphonates
  • Aldendronate - if analgesia fails
22
Q

What is Osteogenesis Imperfecta and how does it occur?

A

A group of genetic disorders that mainly affect the bones. It results in bones that break easily.

People with OI are born with defective connective tissue, or without the ability to make it, usually because of a deficiency of Type-I collagen. As a result, the body may respond by hydrolyzing the improper collagen structure.

If the body does not destroy the improper collagen, the relationship between the collagen fibrils and hydroxyapatite crystals to form bone is altered, causing brittleness.

23
Q

What causes widespread bone pain in osteomalacia?

A

Hydration of mineralised bone puts pressure on periosteum. This causes:

  • Dull Ache
  • Worse at night
24
Q

What is the cause of muscle weakness in osteomalacia?

A

Due to decreased vit D, phosphate and increased PTH

25
Q

What are signs seen in osteomalacia?

A
  • Bone tenderness
  • Waddling gait
  • Proximal weakness
  • Tetany (hypocalcaemia)
26
Q

What are the radiological features of osteomalacia?

A
  • Looser’s zone - cortical fractures on the compression side of the bone
  • Pathological fractures
  • Demineralization
  • Features of HPTH – chondrocalcinosis, subperiosteal erosions
27
Q

What renal diseases can cause vitamin D deficiency?

A
  • Hypophosphataemic renal disease (hereditary and acquired forms)
  • Fanconi syndromes (hereditary and acquired forms)
  • Distal renal tubular acidosis
  • Renal osteodystrophy
28
Q

What are causes of hypovitaminosis D?

A
  • Decreased dietary intake
  • Decreased exposure to sunlight
29
Q

What malabsorptive problems can lead to vitamin D deficiency?

A
  • Coeliac
  • Gastrectomy
  • Pancreatic insufficiency
30
Q

What drugs can cause vitamin D deficiency?

A
  • Anticonvulsants - Phenytoin, carbemazepine
  • Bisphosphonates
31
Q

Why do anticonvulsants cause vitamin D deficiency?

A

Catabolize vitamin D to inactive metabolites

32
Q

Why can someone develop deafness in pagets?

A

Pagetic bone develops in the ear, causing nerve root compression

33
Q

What are the most frequently affected bones in pagets?

A
  1. Pelvis
  2. Lumbar spine
  3. Femur
  4. Thoracic spine
  5. Sacrum
  6. Skull
  7. Tibia
  8. Humerus
34
Q

When investigating pagets disease, which blood test is markedly raisned in isolation?

A

Alk phosphatase

35
Q

What is the most common malignancy associated with Paget’s disease?

A

Osteosarcoma

36
Q

What mnemonic can you use to remember the feautres of PAGETs disease?

A

BAD NEW X-RAY

  • Bone pain
  • Apparent joint pain
  • Deformities (bowed tibia and skull changes)
  • Nerve compression (deafness from compression of cranial nerve VIII, also affects cranial nerves II, V, VII)
  • Elevated bone blood flow (cardiac hypertrophy and high-output cardiac failure)
  • Weakness of abnormal bone leading to pathological fractures
  • X-ray changes
37
Q

What are causes of raised ALP?

A
  • Paget’s Disease
  • Vit D deficiceny - dietary
  • Bone mets
  • 1o or 3o HPTH
  • Cholestasis

Rheumatology (20 decks)

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