Pathway intermediate* | Chemically altered forms¶ | Primary routes of excretion | Samples for measurementΔ |
Delta-aminolevulinic acid (ALA) | None | Kidney | Urine, plasma |
Porphobilinogen (PBG) | Porphobilin; uroporphyrin | Kidney | Urine, plasma |
Uroporphyrinogen (octacarboxyl porphyrin) I & III | Uroporphyrin I & III | Kidney | Urine, plasma |
Heptacarboxyl porphyrinogen I & III | Heptacarboxyl porphyrin I & III | Kidney | Urine, plasma |
Hexacarboxyl porphyrinogen I & III | Heptacarboxyl porphyrin I & III | Kidney | Urine, plasma |
Pentacarboxyl porphyrinogen I & III | Pentacarboxyl porphyrin I & III | Kidney | Urine, plasma |
Coproporphyrinogen (tetracarboxyl-porphyrinogen) I & III | Coproporphyrin I & III | Kidney and liver | Urine, feces, plasma |
Harderoporphyrinogen (tricarboxyl-porphyrinogen) | Harderoporphyrin | Liver | Feces, erythrocytes |
Protoporphyrinogen IX | Protoporphyrin IX | Liver | Feces, plasma |
Protoporphyrin IX | None | Liver | Feces, erythrocytes |
* All intermediates are colorless and nonfluorescent, with the exception of protoporphyrin, which is reddish and fluorescent.
¶ The auto-oxidized porphyrins are reddish and fluorescent; porphobilin is brownish.
Δ Urine and fecal porphyrins are fractionated if the total is increased; plasma porphyrins may be fractionated, but for differential diagnosis it is preferred to determine the fluorescence peak at neutral pH.Do you want to add Medilib to your home screen?