Metabolic Bone Disorders Flashcards

1
Q

What is renal osteodystrophy?

A

Bone mineralization defect secondary to electrolyte and endocrine dysfunction

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2
Q

What is the mechanism behind renal osteodystrophy?

A

Glomerular damage = phosphate retention = hyperparathyroidism
Tubular damage = reduction in 1,25 (OH)2 D3 synthesis

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3
Q

What are Looser’s zones?

A

Pseudofractures/milkmans fractures

Lucencies with sclerotic borders transversing partway across bone

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4
Q

Definitions of Rickets?

A

Defect in mineralization of osteoid matrix secondary to inadequate calcium and phosphate with failure of calcification in zone of provisional calcification

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5
Q

What are the 3 types of Rickets

A
  1. Vit D deficient
  2. Vit D dependant
  3. Vit D resistant (Familial/ Hypophosphatemic)
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6
Q

What is the pathogenesis of Familial/hypophosphatemic/ vit d resistant rickets?

A

Renal phosphate wasting - inability to resorb

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7
Q

What are the inheritance patterns of FR?

A
  1. X linked dominant - MAIN
  2. Autsomal dominant
  3. Autosomal recessive
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8
Q

What gene is mutated and effect in x linked dominant FR?

A

PHEX

Increases FGF 23

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9
Q

What are the two types of Vit D dependant rickets?

RARE AND SEVERE

A

Type 1 - defect of 1 alpha hydroxylase (ENZYME)
Type 2 - end organ resistance to 1,25 vit d (RECEPTORS)
Like type 1/ type 2 diabetes

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10
Q

What is the pathogenesis of vit D def?

A

Decreased intake - Nutritional/ No sunlight

Decreased absorption - Malabsorption

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11
Q

Characteristic lab finding in vit D resistant rickets?

A

Normal Vit D levels

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12
Q

Characteristic lab finding in Vit D def

A

Low Vit D levels

Low ca/po4

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13
Q

Characteristic lab finding in type 1 vit D dependant?

A
  1. V Low Calcitriol levels
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14
Q

Characteristic lab finding in type 2 vit D dependant?

A
  1. V High Calcitriol levels
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15
Q

What is the inheritance pattern of hypophosphotasia?

A

Autosomal recessive

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16
Q

What is the main path behind hypophosphotasia?

A

Mutation in TNSALP

ALP impairment

17
Q

What are the bloods required for investigation of rickets/ metabolic bone disease?

A
Ca
Po4
ALP
25 vit D
Calcitriol
PTH
\+- Alb
18
Q

Treatement of Vit D resistant

A

HIGH vit D/ Calcitriol

Phosphate replacement

19
Q

What are the genetic inheritance patterns for metabolic bone disease?

A

X linked Dom in Familial

ALL the rest = AR

20
Q

Rickets with a closed physis =

A

Osteomalacia