Prevalence and clinical significance of cryofibrinogenaemia in patients with renal disorders.

Background: Cryofibrinogenaemia (CryoFg) is an under-recognized cryoprotein that can be life-threatening when untreated. Symptoms are mainly thrombotic cutaneous manifestations, but other thrombotic localizations may occur. In patients with end-stage renal disease, thromboses are common. However, the implication of CryoFg was never assessed. The aim of this study is to describe the prevalence and the significance of CryoFg in patients with renal disorders.

Methods: One hundred and one consecutive patients admitted in a nephrology department for the management of renal disorders were tested for the presence of serum cryoprotein, i.e. cryoglobulinaemia and CryoFg. We analysed clinical and biological factors associated with the presence of CryoFg.

Results: Among the 101 patients, 11 patients had positive CryoFg without detectable cryoglobulin (11%). Median CryoFg level was 0.07 g/L (0.05-1.16). Main epidemiological features and causes of nephropathy, in particular vascular nephropathies, were similar between CryoFg- and CryoFg+ patients. No biological difference (haematuria, proteinuria, creatinine level and glomerular filtration rate using Modification of Diet in Renal Disease) was found between CryoFg- and CryoFg+ patients. In contrast, CryoFg+ compared to CryoFg- patients had more frequent severe thrombotic events (36 versus 0%, P < 0.0001). Severe thrombotic events included renal artery thrombosis in two patients, recurrent arteriovenous fistula thrombosis in one and recurrent dialysis catheter thrombosis with superior vena cava obstruction in one. The presence of CryoFg was not associated with other manifestations, in particular cutaneous manifestations.

Conclusion: Cryofibrinogenaemia is detected in up to 11% of patients with renal disorders. In such patients, the presence of CryoFg is associated with thrombotic events.