Intraductal Secretin Stimulation Test: What Is the Proper Collection Time?

Abstract

Pancreatic function tests are helpful methods to establish or exclude a diagnosis of chronic pancreatitis (CP). Many studies confirm the clinical utility of the intraductal secretin test (IDST), and that the most discriminatory parameters used are secretory flow rate (SFR) and bicarbonate concentration (BC)∗. Forty-five minutes (min) IDST collection time was recommended by some investigators. A shorter collection time has been proposed to increase the practicality of the IDST, but the precise time has been not well defined. The aim of our study is to establish the IDST proper collection time. Method: The results of 68 IDSTs done in our center were evaluated. Pure pancreatic juice (PPJ) was collected after an IV injection of 16 μg of synthetic secretin (SecreFlo, ChiRhoClin, Inc, Burtonsville). The first 5-min collection was discarded and the PPJ was then collected at 5 minutes intervals up to 45 min. A triple lumen manometry catheter was used to collect the PPJ. The parameters evaluated were the peak SFR, time of peak SFR, max BC (measured by back titration), and time of max BC. Normal SFR was defined as ≥3 ml/min and normal BC was defined as ≥105 mEq/L∗. Results: Max BC was reached by the collection time of 6-10 min in 11 patients (pts) (16%), by 11-15 min in 43 pts (63%), by 16-20 min in 60 pts (88%), by 21-25 min in 65 pts (95%) and by 26-30 min in all pts (100%). Peak SFR was reached by the collection time 6-10 min in 24 pts (36%), by 11-15 min in 37 pts (55%), by 16-20 min in 52 pts (77%), by 21-25 min in 57 pts (84%) and by 26-30 min in all pts (100%). However, all pts reached their final diagnostic classification (normal versus CP) for both the SFR and BC by 20 min collection period [i.e. either the SFR was low (<3 ml/min) from the beginning and remained low throughout the collection time, or normal (≥3 ml/min) within the first 20 min collection time; the same was seen for BC]. Further collection time did not change their final diagnosis. Based on BC criteria, 15 pts had CP (22%). Based on SFR criteria, 31 pts had CP (45%), by either criteria 45% had CP. Summary: The final clinical diagnosis of CP was established or excluded by the first 20 min collection period (for both SFR and BC) in all pts. Conclusions: The first 20-minute collection period during IDST was sufficient time for diagnosing or excluding CP in all pts in this series. This data confirms prior studies showing adequacy of 15-20 min IDST collection time.∗∗Sivak M. Gastroenterologic Endoscopy. 2nd W.B. Saunders Company, 2000:1116-1118.