23 Porphyrias

Porphyrins Metabolism

• anything increases activity of P450 can exacerbate condition

• anemia can result with severe inhibition of enzymes

Porphyria

• two common ones are hepatic porphyria: heme synthesis affected in liver

PCT

• some carboxyl groups have 3 carbons, others 2

• A for acetic, P for propionic

• Uroporphyrinogen III must be oxidized, lose H2, to be converted to uroporphyrin III

• skin major symptoms (cutanea)

• heptatitis from uroporphyrins accumulation in liver

• in kidney: tea colored urine

• iron overload like hemochromatosis

• determine high porphyrin, then fractionate to determine high uroporphyrin

• vampire hypothesis

• consume heme/blood, inhibit heme synthesis

Acute Intermittent

• late in pathway: skin symptoms

• early in pathway: neurologic symptoms

• low glucose, increased ALA synthase, rising heme

• confusion, delirium, dementia

• inhibited porphobilinogen deaminase and increased D ala synthase leads to increased D ala and porphobilinogen

• urine darkens over time

• avoid triggers