Utilization of Des-Gamma-Carboxy-Prothrombin in Estimating Vitamin K Status in People With Cystic Fibrosis: A Single Center Retrospective Review.

BACKGROUND: People with cystic fibrosis (CF) are at increased risk of fat-soluble vitamin (A, D, E, and K) deficiencies secondary to exocrine pancreatic insufficiency (EPI). Estimation of vitamin K deficiency in routine clinical practice is challenging, and no uniform consensus exists due to lack of an accurate clinical test for the evaluation of its status. We aimed to estimate vitamin K status in people with CF using des-gamma-carboxy-prothrombin (DCP). METHODOLOGY: A single-center retrospective chart review was done between 2022 and 2024. Ninety-four (39 pediatric and 55 adult) people with CF were included for final review. RESULTS: The median DCP value was 0.35 ng/mL (IQR 0.2-0.60; range was 0.1-11 ng/mL). Post hoc, we classified patients into low-DCP (0-90th percentile values in DCP or ≤ 2 ng/mL) and high-DCP (91-100th percentile in DCP or >2 ng/mL) groups. Eleven out of 94 (11.7%) patients had DCP > 2 ng/mL; three out of 11 (27%) had advanced CF liver disease (aCFLD), p = 0.011, and another three had other fat-soluble vitamin deficiencies, and low adherence to pancreatic enzymes and/or vitamin supplementation was suspected, p = 0.011. There were no significant differences in demographics (age, gender) or other comorbidities between the groups. CONCLUSION: DCP can be used for estimating vitamin K status, and the prevalence of suboptimal vitamin K status was 11.7%. DCP levels were higher in aCFLD, as well as those with suspected low adherence to pancreatic enzymes and/or vitamin supplementation. Prospective, multicenter clinical trials are needed to evaluate this further.