A PRELIMINARY-REPORT ON URINARY BT-PABA PAS EXCRETION INDEX, SERUM PANCREATIC ISOAMYLASE AND FECAL CHYMOTRYPSIN TESTS OF PANCREATIC DYSFUNCTION IN SOWETAN AFRICANS/

The steady increase in chronic pancreatitis among black Africans at So weto, RSA, in the past 40 years necessitates an objective and non-inva sive test to detect the disease at an early stage. Given the biphasic nature of the disease - secretory hyperfunction with periodic active i nflammatory episodes followed by steady exocrine impairment - we asses sed three potential aids. Urinary BT-PABA/PAS excretion index (PEI), s erum pancreatic isoamylase (PIA) and faecal chymotrypsin activity (FCA ) were measured in the following groups: 16 outwardly healthy hospital workers, 16 consecutive patients with calcifying chronic pancreatitis and 19 with abdominal pain ascribed to other conditions (disease cont rols). (1) Healthy controls had lower PEI than those at Manchester, UK , or Madras, India, from subclinical acinar loss as shown by lower PAP A recovery whereas intestinal absorptive capacity was maintained, as s hown by recovery of PAS, (2) Using the popular cut-off for PEI (0.75) only 9 of 14 patients with chronic pancreatitis were identified (sensi tivity 64%, 2 tests unsatisfactory), while a value of less than 0.54, the mean -2 S.D, in local controls, yielded sensitivity of 50%. (3) If PEI of less than 0.75 or PIA outside the reference range was taken to indicate the disease, 5 of 9 disease controls would have been classed as chronic pancreatitis (among those with both tests satisfactory): r etrospective ultrasound scans did not identify these. (4) Although FCA was less than the preselected cut-off, 5 units/g, in every patient wi th chronic pancreatitis (100% sensitivity) its poor predictive value w as indicated by low specificity: subnormal levels in 4 of 14 and 6 of 16 healthy controls or disease controls, respectively, most of whom ha d near-normal values of PEI, PIA or both. (5) Collectively, these resu lts suggest a high frequency of subclinical chronic pancreatitis at So weto, but also that the combination of tests required to identify it m ay prove impractical - whether in field surveys or hospital practice.