Biochemical studies for the diagnosis of porphyrias

Abstract

Porphyrias are a group of metabolic disorders, either acquired or hereditary, caused by enzymatic deficiencies in the heme biosynthesis pathway, which originates from the precursors glycine and succinyl-CoA. Acquired forms may result from triggering factors such as iron overload, liver diseases, cytochrome P450-inducing drugs, smoking, or alcohol consumption. Depending on the specific enzymatic defect within the metabolic pathway, there is an accumulation of various heme precursors, such as delta-aminolevulinic acid, porphobilinogen and different types of porphyrins (uroporphyrins, coproporphyrins, and protoporphyrins). Porphyrias are classified according to the tissue in which the metabolic defect predominates into hepatic or erythropoietic forms, and based on clinical presentation into acute, cutaneous, or mixed types. Diagnosis relies on the assessment of clinical symptoms and the performance of biochemical and genetic studies, with biochemical studies being essential for confirming and accurately classifying the type of porphyria.