Porphyrinuria

Porphyrinuria is the presence of porphyrins in the urine. It is a laboratory finding that can occur in disorders of heme biosynthesis called porphyrias, and it may be transient or persistent depending on the underlying condition. The pattern of urinary porphyrins and related metabolites helps diagnose and classify these conditions.

In acute hepatic porphyrias—including acute intermittent porphyria, variegate porphyria, and hereditary coproporphyria—attacks are neurovisceral and a porphyrin precursor profile changes during episodes. During symptomatic attacks, levels of delta-aminolevulinic acid and porphobilinogen may be elevated, and later urinary porphyrins such as coproporphyrin and uroporphyrin can be increased. In porphyria cutanea tarda, urinary porphyrin excretion is dominated by marked elevation of uroporphyrin, often with photosensitivity and tea-colored urine.

Diagnosis relies on quantitative urinary porphyrin analysis, typically using fluorometric screening followed by chromatographic methods to identify specific porphyrins. Measurement of porphobilinogen and delta-aminolevulinic acid in urine supports detection of acute attacks and helps distinguish porphyrias from other conditions. Additional evaluation may include liver function tests and genetic testing to confirm the specific subtype.

Management depends on the underlying porphyria. Acute attacks are treated with intravenous hemin, intravenous glucose, and supportive care; avoidance of triggers such as certain drugs, fasting, and alcohol is important. For porphyria cutanea tarda, management may involve phlebotomy to reduce iron stores, low-dose hydroxychloroquine in select cases, and sun protection. Prognosis varies by subtype and severity, but many porphyrias are manageable with timely diagnosis and appropriate therapy.