Porphyrins and Jaundice

Question 1

Where does Heme synthesis take place?

Answer 1

First 1. Last 3 in Mito

Middle 4 in Cyto

Question 2

Steps of Heme Synthesis

Answer 2

1. Succinyl CoA -> ALA (ALA Syn)
2. ALA -> PBG (PBG Syn)
3. PBG -> Urogen III (Urogen Synthetase)
4. UroGen III -> Coprogen III (Urogen Decarb)
5. Coprogen -> Protogen III (Coprogen Oxidase)
6. Protogen -> PPP (Protogen Oxidase)
7. PPP + Fe -> Fe PPP (Ferrochelatase)

Question 3

Control of Heme Synthesis in Liver

Answer 3

Heme:
(-) ALA Syn
(-) Synthesis of ALA Syn
(-) trasnport of ALA syn into mt
Steroids: (+) Heme synthesis
Glucose (-)

Question 4

Control of Heme in Bone Marrow

Answer 4

• Heme (-) Fe uptake + ALA synth activity

- *Erythropoeitin induces ALL enzymes of pathway coordinately

Question 5

Acute Intermittent Porphyria (AIP)

• Path
• S/S
• Precipitation

Answer 5

• Path: Patients excrete ALA & porphobilinogen
• S/S: Abdominal pain, constipation, back/leg pain, hyponatremia, CNS, ***No photosensitivity
• Precipiration: Meds, Mensies, malnutrition, maladies

Question 6

What causes the Neural S/S in AIP?

Answer 6

Conversion of tryptophan into N-formylkynirinine

Question 7

Porphyria Cutanea Tarda

• Path
• S/S
• LabDx

Answer 7

• Path: UROD Deficiency (5th step)
• S/S: **Photosensitivity, Hirsutism, impaired liver function, Hepatic Fe excess; Finger-like protrusion on hand
• Lab Dx: UV Fluorescent Urine;

Question 8

Plumbism

• Path
• S/S

Answer 8

• Path: Pb Poison which inhibits ALA Dehydratase + Ferrochelatase
• S/S: Mimics PCT

Question 9

What important 2nd function does Bilirubin have?

Answer 9

Antioxidant

Question 10

What is Jaundice? What are it’s causes?

Answer 10

• High plasma Bilirubin (>2.0 - 2.5 mg/dl)

- Caused by hemolysis, liver disease, or bile duct obstruction