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Derm 2020 > Porphyrias > Flashcards

Porphyrias Flashcards

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1
Q

Porphyria cutanea tarda usually presents during the first and second decades of life

A

False third to fourth , usually not before puberty

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2
Q

Acquired type 1 PCT represents 75% of cases, presenting in middle age

A

True

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3
Q

Type II is familial UROD gene mutation accounting for 25%

A

True

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4
Q

Risk factors for PCT

A 
Alcohol
UROD deficiency
Hepatocellular ca
Dialysis in renal failure 
Iron overload H63D/C282Y
Hep B, Hep C
Male
Age >50
Hereditary haemochromatosis
OCP and exogenous oestrogens in females
Exogenous agents such as halogenated hydrocarbons
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5
Q

Biochemical findings of PCT

A

Urine - uroporphyrin III
Faeces- Isocoporphyrin
Peak plasma fluorimetry 615-620nm

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6
Q

Natural course of PCT

A

Blisters first remit 2-3 mo
Fragility takes 6-9 mo
Porphyrins take 12 mo to normalise
Hypertrichosis, sclerodermoid changes take years

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7
Q

Aims of PCT treatment and targets

A

Induce mild Fe deficiency to reduce triggering haem synthesis
Aim of Hb 110-120
Fe <25
These can take 13 mo to achieve

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8
Q

Features of congenital ERYTHROPOETIC porphyria

A

Presents with hydrops details, through to severe disease starting in infancy, but mild forms can present later in life

  • first sign might be noting brown discolouration of amniotic fluid at onset of labour or pink/brown/violet porphyrins staining (red orange under Wood lamp)
  • severe photosensitivity begins in infancy
  • = blisters develop on minimal sun exposure
  • exposed skin is fragile
  • erythrodontia may be evident
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9
Q

CEP biochemical findings

A

Urine - uroporphyrin I
Faeces - coproporphyrin I
Red cell - zinc and free protoporphyrin , uroporphyrin I, coproporphyrin I

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10
Q

Extracutaneous features of CEP

A

Eyes- keratoconjunctivitis, cataracts, scarring alopecia eyelashes and eyebrows, corneal ulcers
Bones and teeth - teeth almost always stained brain , decr bone density are seen with pathological fractures
Haemolytic anaemia - due to marrow hyperplasia

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11
Q

Erythropoetic porphyria inheritance

A

Newly classified AR - previously AD with incomplete penetrance

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12
Q

EPP develop significant blisters in the first few years of life

A

False - oedema and pain

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13
Q

Late onset of EPP is common

A

False - rare

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14
Q

EPP 5% liver failure

A

True

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15
Q

Hereditary coprophyria develop acute attacks without blisters

A

False, do get blisters

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16
Q

HC Is autosomal dominant

A

True

17
Q

Deficiency in HC is ferrochelotase

A

False, coproporphyrinogen oxidase . Ferrochelotase is deficient in EPP

18
Q

HC has incr uro and coproporphyrin concentrations in urine and incr coproporphyrin in faces

A

True

19
Q

Variegate porphyria is autosomal recessive

A

False, dominant

20
Q

Risk of offspring developing VP is 50%

A

True as it is autosomal dominant

21
Q

Protophyrinogen oxidase is the deficiency in VP

A

True

22
Q

VP usually presents in infancy or childhood

A

False - adolescence or young adulthood

23
Q

VP indistinguishable from PCT

A

True

24
Q

VP biochemical findings

A

Urine coprophyrinoge, faecal coprophyrinogen , plasma fluorimetry is diagnostic with peak at 626nm

25
Q

Symptoms of an acute porphyria attack

A

GI - colicky abdo pain, nausea , vomiting, hyponatraemia
Neurologic - seizures, psychosis, coma, paraesthesias, motor neuropathy, anxiety, muscle and back pain
Cardiopulmonary - tachycardia, HTN, respiratory paralysis

26
Q

Management of acute attack

A

Key is early diagnosis
Avoid attack inducing drugs
Supportive Tx —> analgesia, usual tx safe ie. aspirin, morphine, ondansetron, 300mg CHO, B blockers for tachycardia and HTN, fluid balance and rehydration, correct hyponatraemia

27
Q

What can trigger an acute porphyria attack

A 
P450 drugs (SHOEBAGS)
Hormones
Stress
Fasting - need to advise carry sweets
Surgery
Infection
DRUGS:
Sulfur
Hormones
OCP
Epileptics
Barbiturates
Antimalarials and amphetamines 
Griseofulvin
Sedatives
28
Q

Pseudoporphyria drugs

A 
NAT CL 
NSAIDs
Tetracyclines
Lasix
Amiodarone
Ciprofloxacin

Derm 2020 (59 decks)

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