Cryoglobulinemia-associated kidney disease: long-term insights into pathology, outcomes, and prognostic factors

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Abstract Background Cryoglobulinemia is an immune complex–mediated disorder defined by the presence of circulating immunoglobulins that precipitate at temperatures below 37 °C and redissolve upon warming. It may lead to systemic small-vessel vasculitis, with the kidney being one of the most frequently and severely affected organs. This study aimed to characterize the clinical, biological, and histopathological features of cryoglobulinemia-associated renal disease, to identify underlying etiologies, and to assess renal outcomes. Methods We performed a retrospective observational study including 50 patients with cryoglobulinemia-associated renal involvement, followed in the Department of Nephrology at Charles Nicolle Hospital, Tunis, between 1981 and 2022. Renal involvement was defined on the basis of clinical manifestations, laboratory and immunological abnormalities, and kidney biopsy findings. Results The mean age was 55 ± 13.3 years, with a male-to-female ratio of 0.51. The most frequent renal presentations were acute or chronic renal failure (30%) and nephrotic syndrome (24%). Extra-renal manifestations included articular involvement (42%), cutaneous lesions (38%), and neurological involvement (32%). Renal impairment was observed in 36 patients (72%), with a mean serum creatinine level of 266 ± 245 µmol/L and a median 24-hour proteinuria of 1.5 g (range 0.07–16.09). Kidney biopsy was performed in 32 patients (64%) and predominantly showed membranoproliferative glomerulonephritis (62%). Cryoglobulinemia was secondary in 29 patients (58%), predominantly associated with hepatitis C infection, and essential in 21 patients (42%). Therapeutic management included oral corticosteroids in 46% of patients, combined with monthly cyclophosphamide pulses in six cases and rituximab in two cases. After a median follow-up of 24 months (range 3–324), 19 patients (38%) progressed to chronic kidney disease, while 18 patients (36%) achieved renal remission at six months. Overall clinical remission was observed in 34 patients (68%). Infectious complications occurred in 16% of patients, and five deaths (9.8%) were recorded during follow-up. Conclusion Cryoglobulinemia-associated renal disease was marked by severe initial presentation and limited renal recovery, with half of patients failing to achieve remission at six months. Baseline renal dysfunction and intracapillary thrombi were associated with progression to end-stage kidney disease (ESKD), highlighting the importance of early renal assessment and kidney biopsy for risk stratification.

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