Extremely high levels of ALA and PBG in the urine with normal porphyrin levels in the feces and blood most likely indicate which porphyria?

• A. Acute intermittent porphyria (AIP)
• B. Erythropoietic porphyria (EP)
• C. Hereditary coproporphyria (HCP)
• D. Porphyria cutanea tarda (PCT)

Answer: (A)

High urinary ALA and PBG with normal fecal and blood porphyrins point to an acute hepatic porphyria, specifically acute intermittent porphyria. This pattern arises because the deficiency is in the enzyme that converts PBG to the next step (PBG deaminase), causing a buildup of the precursors ALA and PBG that are excreted in urine. Porphyrins in feces and blood remain normal because the downstream products aren’t being produced in excess. Clinically, this aligns with neurovisceral symptoms rather than skin photosensitivity, which helps distinguish it from other porphyrias that elevate different porphyrins in urine, feces, or tissues.