Yasemin Akgul Balaban, Mustafa Ilker Inan, Fikriye Kalkan, Ezgi Sonmez, Galip Buyukturan, Fevzi Demirel, Ali Selcuk, Sait Yesillik, Yusuf Serdar Sakin, Ozgur Kartal
Transient abnormalities in C1-inhibitor functional activity and C1q may occur during IAP attacks and resolve after recovery. These findings suggest that complement test results obtained during an acute-phase pancreatitis episode should be interpreted cautiously when evaluating patients for hereditary angioedema. When HAE is clinically suspected, abnormal complement results should be confirmed after clinical remission before establishing a diagnosis of C1-inhibitor deficiency.
PURPOSE: Hereditary angioedema (HAE) is an important but uncommon differential diagnosis in patients presenting with unexplained recurrent abdominal attacks, including idiopathic acute pancreatitis (IAP). However, whether acute IAP itself transiently affects complement test results and complicates the evaluation of HAE remains unclear. This prospective study investigated changes in C1-inhibitor (C1-INH) function and complement parameters during acute IAP and after clinical recovery.
METHODS: In this prospective observational study, 54 adult patients diagnosed with IAP according to the revised Atlanta criteria were initially enrolled. Three patients with incomplete baseline complement measurements were excluded from the longitudinal analysis, resulting in a final analytic cohort of 51 patients. Serum C4, C1-inhibitor antigenic level, C1-inhibitor functional activity, and C1q levels were measured during the acute-phase episode. Patients with abnormal complement parameters underwent repeat testing 8 weeks after clinical recovery.
RESULTS: Four patients (7.8%) demonstrated reduced C1-inhibitor functional activity, and one patient (2.0%) had a reduced C1q level during the acute episode. All abnormal complement parameters in patients who underwent follow-up testing normalized at 8 weeks. No persistent C1-inhibitor deficiency or persistently reduced C1q levels were identified after recovery. Patients with transient complement abnormalities showed no distinctive biochemical features compared with the remaining cohort.
CONCLUSION: Transient abnormalities in C1-inhibitor functional activity and C1q may occur during IAP attacks and resolve after recovery. These findings suggest that complement test results obtained during an acute-phase pancreatitis episode should be interpreted cautiously when evaluating patients for hereditary angioedema. When HAE is clinically suspected, abnormal complement results should be confirmed after clinical remission before establishing a diagnosis of C1-inhibitor deficiency.