Wallach's Interpretation of Diagnostic Tests: Pathways to Arriving at a Clinical Diagnosis (129 page)

Serum pancreolauryl test
: Fluorescein dilaurate with breakfast is acted on by a pancreas-specific cholesterol ester hydrolase–releasing fluorescein, which is absorbed from gut and measured in serum; preceded by administration of secretin and followed by metoclopramide. Reported S/S = 82%/91%.

Glucose tolerance test (GTT)
: In 65% of patients with chronic pancreatitis and frank diabetes in >10% of patients with chronic relapsing pancreatitis. When GTT is normal in the presence of steatorrhea, the cause should be sought elsewhere than in the pancreas.

Laboratory findings due to malabsorption
: Occurs when >90% of exocrine function is lost.

   Bentiromide test is usually abnormal with moderate to severe pancreatic insufficiency but often normal in early cases.

   Schilling test may show mild malabsorption of vitamin B
₁₂
(no longer performed).

   Xylose tolerance test and small bowel biopsy are not usually done but are normal.

   Chemical determination of fecal fat demonstrates steatorrhea. It is more sensitive than tests using triolein-
¹³¹
I.

   Triolein-
¹³¹
I is abnormal in one third of patients with chronic pancreatitis.

   Starch tolerance test is abnormal in 25% of patients with chronic pancreatitis.

Laboratory findings due to chronic pancreatitis and pancreatic exocrine insufficiency
:

   Alcohol in 60–70%

   Idiopathic in 30–40%

   Obstruction of pancreatic duct (e.g., trauma, pseudocyst, pancreas divisum, cancer, or obstruction of duct or ampulla)

   Others occasionally (e.g., CF, primary hyperparathyroidism, heredity, malnutrition, miscellaneous [Z-E syndrome, Shwachman syndrome, alpha
₁
-antitrypsin deficiency, trypsinogen deficiency, enterokinase deficiency, hemochromatosis, parenteral hyperalimentation])

PSEUDOCYST OF THE PANCREAS

   Laboratory Findings

Imaging studies
: Detected by ultrasound or CT scan.

Core laboratory
: Serum conjugated bilirubin is increased (>2 mg/dL) in 10% of patients. Serum ALP is increased in 10% of patients. Fasting blood sugar is increased in <10% of patients.

Secretin–pancreozymin stimulation
: Duodenal contents usually show decreased bicarbonate content (<70 mEq/L) but normal volume and normal content of amylase, lipase, and trypsin.

Pancreatic cyst fluid findings
: High fluid viscosity and CEA indicate mucinous differentiation and exclude pseudocyst, serous cystadenoma, other nonmucinous cysts, or cystic tumors. Pancreatic enzymes, leukocyte esterase, and NB/70K are increased in pseudocyst fluid. Increased CA 72-4, CA 15-3, and tissue polypeptide antigen are markers of malignancy; if all are low, pseudocyst or serous cystadenoma is most likely. CA 125 is increased in serous cystadenoma.