Test Database

Porphyrins are intermediates in the haem biosynthesis pathway. Semi-quantitation of total faecal porphyrins is recommended following a positive blood or urine porphyrin screen, to support the diagnosis and differentiation of porphyria. If total faecal porphyrins are elevated, the sample is subsequently analysed by high-performance liquid chromatography (HPLC) for porphyrin fractionation, which helps identify the characteristic porphyrin pattern and determine the specific type of porphyria. Increased faecal porphyrin concentrations are typically observed in: Hereditary Coproporphyria (HCP), Variegate Porphyria (VP), Porphyria Cutanea Tarda (PCT), and Congenital Erythropoietic Porphyria (CEP). Normal or mildly elevated levels may be seen in: Acute Intermittent Porphyria (AIP), Erythropoietic Protoporphyria (EPP) and X-linked Protoporphyria (XLP). It is important to note that marginal elevations in faecal porphyrins can occur due to non-porphyric causes, such as the bacterial degradation of dietary haem or gastrointestinal bleeding. Reported porphyrin fractions in faeces include: (bullet points) Coproporphyrin I, Coproporphyrin III, Total Coproporphyrin (I + III), Dicarboxylate Porphyrin.