PBG/Creatinine Ratio

An elevated PBG/Creatinine Ratio on the Porphobilinogen, Quantitative, Random Urine (Porphobilinogen, Qn, Random Ur) panel by Labcorp can indicate abnormal porphyrin metabolism, which is most often associated with acute porphyrias, particularly:

Acute Intermittent Porphyria (AIP)

This is the most common type of acute hepatic porphyria, a rare genetic disorder where the body has trouble converting porphyrins into heme—a vital component of hemoglobin.

What does the PBG/Creatinine Ratio measure?

• Porphobilinogen (PBG) is a precursor in the heme synthesis pathway.

• Since urine concentration can vary, PBG is standardized against creatinine to produce a more reliable PBG/Creatinine Ratio.

• Elevated ratios mean there’s more PBG than expected relative to creatinine, which is abnormal.

What does an elevated result suggest?

A high PBG/Creatinine ratio may indicate:

• Acute Intermittent Porphyria (AIP)

• Hereditary Coproporphyria (HCP)

• Variegate Porphyria (VP)
  These conditions may present with acute neurovisceral attacks, including:

• Severe abdominal pain

• Muscle weakness

• Anxiety, confusion, or hallucinations

• Hypertension or tachycardia

• Dark or reddish urine (especially during attacks)

Note: Elevated PBG is often intermittent and peaks during an acute attack. Between attacks, levels may normalize—so testing during symptoms is critical for diagnosis.

What should you do next?

If your PBG/Creatinine Ratio is elevated:

• Your doctor may order confirmatory tests, such as:

  • Total urine porphyrins

  • Delta-aminolevulinic acid (ALA)

  • Genetic testing for porphyria types

• Avoid triggers of acute attacks like:

  • Certain medications

  • Fasting or crash diets

  • Alcohol

  • Hormonal fluctuations (e.g., during menstruation)

Bottom Line

An elevated PBG/Creatinine Ratio on a random urine test may signal an acute porphyria, especially if symptoms match. Early diagnosis and avoidance of triggers can help prevent life-threatening attacks and improve long-term outcomes.

The "PBG/Creatinine Ratio" marker found on a Porphobilinogen, Quantitative, Random Urine panel by LabCorp is a crucial test for evaluating the presence and concentration of porphobilinogen (PBG) in urine in relation to creatinine levels. This test is significant for diagnosing and monitoring conditions related to abnormal porphyrin metabolism, such as acute intermittent porphyria, among others. Porphyria refers to a group of disorders that result from a buildup of natural chemicals that produce porphyrin in your body.

Porphobilinogen is a precursor in the biosynthesis of heme, the iron-containing prosthetic group found in hemoglobin. Normally, the body regulates the production of porphobilinogen and other intermediates in the heme production pathway. However, genetic conditions can disrupt this balance, leading to the accumulation of toxic precursors like PBG.