Heme synthesis, Porphyrias & Lead poisoning Flashcards
What are porphyrias?
Hereditary or acquired cond of defective heme synthesis that l/t the accumulation of heme precursors
What does lead inhibit?
Specific enzymes needed in heme synthesis l/t cond similar to porphyria
Which enzyme is affected in Lead poisoning?
Ferrochelatase (mitochondria) & ALA dehydratase (cytoplasm)
Which substances are accumulated in Lead poisoning?
- Protoporphyrin
- Delta-ALA (blood)
What are the overall presenting sx in Lead poisoning?
- Microcytic anemia
- GI & kidney dz
What are the presenting sx in children w/ lead poisoning?
Exposure to lead paint→ mental deterioration
What are the presenting sx in Adults w/ lead poisoning?
Environmental exposure (battery, ammunition, radiator factor)→ HA, memory loss, demyelination
What enzyme is affected in Acute intermittent porphyria?
Porphobilinogen deaminase
(cytoplasm)
What substances are accumulated in Acute intermittent porphyria?
- Porphobilinogen
- Delta-ALA
- Uroporphyrin (urine)
What are the presenting sx Acute intermittent porphyria?
- Painful abd
- Port wine-colored urine
- Polyneuropathy
- Psychological disturbances
- Precipitated by drugs
What is the tx for Acute intermittent porphyria?
Glucose & heme which inhibit ALA synthase
Which enzyme is affected in Porphyria cutanea tarda?
Uroporphyrinogen decarboxylase
(cytoplasm)
What is the accumulated substrate in Porphyria cutanea tarda?
Uroporphyrin (tea-colored urine)
What is the presenting sx in Porphyria cutanea tarda?
Blistering cutaneous photosensitivity
What is the MC porphyria?
Porphyria cutanea tarda
What Heme synthesis enzyme is affected in Sideroblastic anemia (X-linked)?
Delta-aminolevulinic acid synthase
Mitochondria
(rate-limiting step)
Decreased heme increases ___ ____.
ALA synthase activity
