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
