Effect of octreotide on gastrostomy, duodenostomy, and cholecystostomy effluents: A physiologic study of fluid and electrolyte balance

Objectives: Octreotide, a somatostatin analog, reduces stool and fistula outputs by a mechanism that is not completely understood. Our aim was to study its effect on gastrostomy, duodenostomy, and cholecystostomy effluents in a patient with colorectal cancer. Methods: Effluents of gastrostomy, duodenostomy, and cholecystostomy were collected in three separate shifts over 24-h periods beginning 3 days before octreotide therapy and continuing for 15 treatment days. Fifty-four samples were tested for volume, pH, acid, and bicarbonate production, and biochemical profiles. Results: A positive fluid balance was achieved immediately with octreotide therapy. Significant decreases in gastrostomy and duodenostomy outputs and in gastric acid production were observed (1433.33 ± 33.33 ml/24 h to 535.71 ± 55.31 ml/24 h, p < 0.0001; 2066.67 ± 66.67 ml/24 h to 247.14 ± 36.04 ml/24 h, p < 0.0001; and 67.50 ± 3.20 mEq/h to 13.00 ± 1.50 mEq/h, p < 0.0001; respectively). Gastrostomy tachyphylaxis was observed after 6 days of treatment. Remarkable dose-dependent increases were found in cholesterol and bilirubin concentrations in the cholecystostomy effluent. Conclusions: Octreotide's primary effect is a decrease in gastric and pancreatic secretions. The increased concentrations of cholesterol and bilirubin may explain the occurrence of gallstones in patients treated with octreotide.