Delta-aminolevulinic acid dehydratase (ALAD) deficiency porphyria is an extremely rare autosomal recessive acute porphyria. Which pattern of urine metabolite elevation is characteristic?

• A Elevated ALA with normal PBG ✓
• B Elevated PBG with normal ALA
• C Elevated uroporphyrin only
• D Elevated coproporphyrin only

Explanation

ALAD deficiency porphyria (plumboporphyria-like) blocks the second step of heme synthesis, so ALA accumulates but PBG is not formed in excess. This distinguishes it from AIP, where PBGD deficiency causes both ALA and PBG to rise. The pattern mimics lead poisoning biochemically, though ALAD deficiency is genetic rather than toxic.

Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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