Porphobilinogen (qualitative), in Visit Clinic

Porphobilinogen (PBG) quantitative urine is a lab test that measures porphobilinogen, a heme precursor, excreted in urine. It is used to diagnose and monitor acute porphyrias, especially during neurovisceral or abdominal attacks. Elevated urinary PBG strongly suggests an acute porphyria and typically prompts urgent specialist assessment. Samples are best collected during symptoms and may need acidification or refrigeration.

A urine porphobilinogen (PBG) test commonly ranges from about $30–$250 depending on country, laboratory, and whether it’s done privately or covered by public healthcare or insurance. In some regions public health services provide it at no direct cost, while private labs or specialized confirmatory assays can be pricier. Contact your local lab or clinician for exact pricing and coverage.

Porphobilinogen (PBG) appears in urine when a block in heme synthesis leads to PBG buildup—most commonly from acute hepatic porphyrias (for example, acute intermittent porphyria) due to inherited enzyme defects. Attacks are often triggered by certain drugs, alcohol, hormonal changes, fasting/low‑carbohydrate diets, infections, stress or surgery, which increase PBG production and urinary excretion.

Postprandial blood glucose (PBG)—measured about 2 hours after eating—is normally below 140 mg/dL (7.8 mmol/L) in people without diabetes. Values of 140–199 mg/dL suggest impaired glucose tolerance. For people with diabetes, individual targets vary, commonly aiming for under 180 mg/dL (10.0 mmol/L) two hours after meals; consult your clinician for personalized goals.

Confirmatory testing for porphyria is molecular genetic testing demonstrating a pathogenic variant in the relevant heme‑biosynthesis gene. When genetics aren’t available, subtype confirmation uses biochemical methods: enzyme assays (e.g., reduced erythrocyte PBG deaminase in acute intermittent porphyria) and detailed urine, plasma and fecal porphyrin profiling to define the specific disorder.

Porphyria commonly causes dark, red, brown or tea/cola‑colored urine that often darkens further on standing or exposure to light. During acute attacks urine contains elevated porphyrin precursors (porphobilinogen, ALA) and porphyrins, producing a reddish or “port‑wine” discoloration. Routine testing shows increased urinary porphyrins/porphobilinogen; urinary pain or frequency are not typical primary features.