Lundh meal: a single non-invasive challenge test for evaluation of exocrine and endocrine pancreatic function in cystic fibrosis patients

Abstract

The determination of endocrine and exocrine pancreatic function in cystic fibrosis patients is clinically important. Recently, a new non-invasive test, in which pancreatic stimulation by a Lundh meal is followed by sequential serum lipase measurements, was found to be a good indicator of exocrine pancreatic status. Since the Lundh meal also contains glucose, the present study assessed whether it also might be suitable for evaluation of the pancreatic endocrine axis. After an overnight fast, 10 healthy non-diabetic subjects and 14 cystic fibrosis patients ingested a Lundh meal. Glucose, insulin, and C peptide levels were measured at various time intervals following the meal. For purposes of comparison, the oral glucose tolerance test was also performed on the cystic fibrosis patients. All healthy subjects demonstrated an increase in glucose levels post Lundh meal, peaking at 45 min (mean 140±21 mg/dl) and then gradually declining and reaching the normal range at 120 min. Concordant peaks of insulin (46.3±20 IU/ml) and C peptide (5.8±1.5 ng/ml) levels were noted at 60 min. All 14 cystic fibrosis patients had normal basal glucose levels: in 8, the pattern of glucose, insulin, and C peptide post Lundh meal was similar to that of the healthy controls. These 8 patients also had a normal basal glucose levels: in 8, the pattern of glucose, insulin, and C peptide post Lundh meal was similar to that of the healthy controls. These 8 patients also had a normal oral glucose tolerance test, and their hemoglobin A_1C levels were within the normal range. The other 6 cystic fibrosis patients demonstrated glucose levels above 200 mg/dl 30–60 min post Lundh meal, and all also had an impaired oral glucose tolerance test. Of these 6, 4 had high levels of hemoglobin A_1C. This study demonstrates that the Lundh meal challenges the endocrine pancreas as well as the oral glucose tolerance test. Thus, determination of both exocrine and endocrine pancreatic status can be achieved by a single non-invasive test.