The serum concentration of insulin, C-peptide, and proinsulin in patients with acute pancreatitis

Summary In 14 patients with acute pancreatitis during 16 episodes of the disease the concentrations of blood glucose, serum insulin (IRI), C-peptide (CP), and proinsulin (Pro) were determined in the fasting state on d 1, 2, 3, 5, and 10 after the attack. The peptides were measured using RIAs, and for determination fo CP two antibodies: Byk-Mallinckrodt’s and more specific M-1221 Novo antibodies were used. Apart from sporadic rises in the initial period of the disease, the blood glucose level did not change significantly and had a decreasing trend. On d 1 the mean serum IRI level was 0.17±0.04 (SD) nM, and it decreased on d 5 to 0.06±0.04 nM, rising again to 0.11±0.15 nM on d 10. The serum Pro concentration was on the same days: 11.1±12.6, 4.2±2.4 and 7.5±10.8 pM, whereas the serum CP values determined with M-1221 antibodies were 0.48±0.50, 0.34±0.19, and 0.52±0.25 nM, respectively. However, when serum CP was determined using Byk-Mallinckrodt kits, the concentration on d 1 was 1.90±1.12 nM and over the following days it decreased to 1.08±0.98 nM on d 5 and on d 10 it was 1.11±0.46 nM. In one patient (not included in the calculation of the mean values), in whom the second attack of acute pancreatitis had a fatal outcome, the serum levels of all three peptides were very high, with a particularly evident difference of CP-values, dependent on the antibodies used: 2.47 nM with M-1221 antibodies and 9.90 mM with Byk-Mallinckrodt kits on d 5. We hypothesize that the transient decrease of the serum peptides released into the blood in the process of insulin biosynthesis observed in the early period of acute pancreatitis is owing to their breakdown by the activated pancreatic proteases. Our observation suggests also that in acute pancreatitis in blood appeared an unidentified protein reacting with less specific antibodies to C-peptide.