The endoscopic pancreatic function test-time to take a step back

Comparison of autoanalyzer and back titration for measurement of bicarbonate concentration in endoscopically collected pancreatic fluid

OBJECTIVES

In secretin-stimulated pancreatic function testing, the standard technique for bicarbonate measurement is back titration (BT). Chemistry autoanalyzers (AAs) automate bicarbonate measurement and are universally available; however, this method has not been validated in pancreatic fluid. The aims of the study were (1) to compare the AA and BT for measurement of bicarbonate in pancreatic fluid and (2) to determine the effects of variable conditions on bicarbonate concentration.

METHODS

Pancreatic fluid samples were analyzed for bicarbonate concentration using both BT and AA. Additional experiments were conducted to determine the effect of different sample conditions.

RESULTS

The results obtained by BT and AA were highly concordant (Lin concordance coefficient, 0.96). An AA cutpoint of 84 mM optimized sensitivity (91.1%) and specificity (94.1%) compared with the BT reference standard. Blood contamination spuriously increased the bicarbonate, an effect that was eliminated by centrifugation. The bicarbonate levels were not significantly affected by delayed analysis, storage condition, nitrogen gas treatment, or the addition of mineral oil or protease inhibitors.

CONCLUSIONS

The bicarbonate concentrations obtained by AA are highly concordant with those obtained by BT. Secretin pancreatic function testing fluid analysis may now be performed in any hospital.

Evaluation of duct-cell and acinar-cell function and endosonographic abnormalities in patients with suspected chronic pancreatitis

BACKGROUND & AIMS

Endoscopic ultrasound (EUS) detects mild and severe structural abnormalities of the pancreas that correlate with fibrosis. Direct pancreatic function tests (PFTs) detect mild exocrine insufficiency associated with early fibrosis. The primary aim of this study was to compare EUS structural criteria with duct-cell and acinar-cell function.

METHODS

Fifty patients evaluated for chronic pancreatitis underwent combined EUS and secretin endoscopic PFTs (ePFT) on day 1 and CCK ePFT on day 2. EUS images were videotaped and interpreted by consensus of 3 blinded expert reviewers.

RESULTS

There were inverse correlations of EUS consensus score with both duct-cell bicarbonate secretion (R = -0.71, P < .001) and acinar-cell lipase secretion (R = -0.52, P < .001). With secretin ePFT as reference standard, EUS (>or=4 criteria) showed a sensitivity of 71% (95% confidence interval [CI], 53%-89%) and specificity of 92% (95% CI, 75%-99%). With CCK ePFT as reference standard, EUS had a sensitivity of 63% (95% CI, 43%-82%) and specificity of 85% (95% CI, 71%-98%). Main duct dilation, irregularity, calcifications, and visible side-branches were most predictive of exocrine insufficiency (positive predictive value >80% for both acinar- and duct-cell insufficiency).

CONCLUSIONS

Acinar- and duct-cell function decreases as EUS structural abnormalities increase. EUS has fair sensitivity and very good specificity compared with secretin and CCK functional reference standards.