Porphyrias

Question 1

Describe the heme biosynthesis pathway

Answer 1

Glycine + succinyl Co A
( ala synthase) // SIDEROBLASTIC ANAEMIA
→ ALA Aminolevulinic acid
(Pbg synthase/ALA dehydratase) // PLUMBOPORPHYRIA/DELTA ALA DEHYDRATASE PORPHYRIA
→ PBG porphobilinogen
( PBG deaminase) // * ACUTE INTERMITTENT PORPHYRIA
→ hydroxymethylbilane →uroporphyrinogen 1→ coproporphyrinogen 1
( uro’gen co-synthase) ↳ ( uro’gen decarboxylase) → coproporphyrinogen 3
//CONGENITAL ERYTROPOIETIC PORPHYRIA
→ uroporphyrinogen 3
( uroporphyrinogen decarboxylase) // PORPHYRIA CUTANEA TARDA
→ coproporphyrinogen 3
(Copro’gen oxidase ) // HEREDITARY COPROPORPHYRIA
→ protoporphyrinogen
(Proto’gen oxidase ) // VARIEGATE PORPHYRIA
→ protoporphyrin
(Ferrochelatase) // ERYTHROPOIETIC PROTOPORPHYRIA
→ heme

Get Some Additional Points Having Understood the Correct Pathway for Heme
Porphyria’s Are Crazy Cunts. Health’s Very Exhausting
SSDCDOOF (enzymes)

Question 2

Name the symptoms of acute intermittent porphyria

Answer 2

Mostly asymptomatic, no skin lesions
Neurovisceral features in acute phase: stomach ache, can have psych symptoms
5 Ps: Pain abdo, polyneuropathy, port wine coloured urine?, psychological symptoms, P450 inducers cause (phenytoin, barbs, sulfonamides)

Question 3

Name 6 causes of secondary porphyrias

Answer 3

• Lead toxicity (inhibit Ala dehydratase, coproporphyrinogen oxidase and ferrochelatase → decrease haem synth (anemia), increase urinary Ala and coproporphyrin with normal PBG, increase RBC zn protoporphyrin )
• liver disease (raise urine coproporphyrin)
• chronic kidney failure
• malignancy
. Toxin exposure: heavy metals, solvents
• bleeding stomach or duodenal ulcers (raise fecal porphyrins due to breakdown of hb in gut)

Question 4

Name the 3 acute porphyria’s

Answer 4

• Acute intermittent porphyria
• hereditary coproporphyria
• variegate porphyria

Question 5

Symptoms variegate porphyria?

Answer 5

Acute phase: neurovisceral features (excessive Ala and PBG production)
Latent phase: asymptomatic or skin lesions (enzyme defect)

Question 6

Treatment acute phase porphyria? (5)

Answer 6

Supportive
• maintain fluid and electrolytes
• adequate carb intake
• iv heme arginate
• pain relief
• anti emetics

Question 7

Name symptoms and 3 triggers porphyria cutanea tarda

Answer 7

Skin lesions only: hypertrichosis, hyperpigment

Triggers: alcohol abuse, iron overload, estrogens

Question 8

Name 4 clinical features congenital erythropoietiC porphyria

Answer 8

• Severe photosensitivity with scarring from infancy
• hypertrichosis, alopecia
• brownish pink teeth that fluoresce red in uv light

• haemolytic anaemia