5-Aminolevulinic acid-13C-1 (5-ALA-13C-1) hydrochloride is the 13C labeled 5-Aminolevulinic acid hydrochloride[1]. 5-Aminolevulinic acid hydrochloride (5-ALA hydrochloride) is an intermediate in heme biosynthesis in the body and the universal precursor of tetrapyrroles[2][3].