PABA Test

The PABA test is used to detect pancreatic exocrine insufficiency, ie failure of the pancreas to produce sufficient enzymes for complete digestion.

The principle behind the test is simple. After fasting overnight, the patient is given a fixed dose of a peptide comprising N-benzoyl-L-tyrosyl-pa-aminobenzoic acid (NBT-PABA). In a patient with normal pancreatic exocrine function, pancreatic enzymes break down NBT-PABA into the smaller compound PABA, which is then absorbed and excreted in the urine. Normally more than 70% of the dose administered appears in the urine. Less than 70% excretion implies that the exocrine activity of the pancreas is impaired.

DON’T FORGET

Normally >70% of the oral PABA dose is detected in the urine.