Laboratory Practices for the Detection and Characterization of Cryoglobulins and Cryofibrinogen.

Background: Cryoglobulins (CGs) and Cryofibrinogen (CF) are proteins that precipitate at low temperatures. Complex laboratory procedures are necessary to identify them.

Methods: Between December 2022 and December 2023, 1171 patient samples for analysis of CGs and CF were received in the laboratory from different clinical departments with suggestive clinical symptoms and signs of cryoproteinemia and were analyzed using pre-analytical, analytical, and post-analytical procedures.

Results: Cryoproteins were detected in 281 samples (47%); CGs⁺ were found in association with CF⁺ in 74 samples (12.52%); CF⁺ was detected with CGs^- in 119 patients (20.13%); and CGs⁺ were found with CF^- in 88 patients (14.9%).

Conclusions: CGs testing has long been common in laboratories, and the analytical and pre-analytical procedures are well known, in contrast to CF testing, which has only emerged in recent years. Therefore, appropriate procedures are needed for testing both cryoproteins to optimize economic and human resources and reduce laboratory diagnostic times. At last, confirming a clinical suspicion of cryoproteinemia in a short time could improve patient outcomes, allowing suitable therapies to be implemented for vasculitis and related thromboembolic phenomena.