Monoclonal gammopathy after liver transplantation: a risk factor for long-term medical complications other than malignancies.

The aims of the study were to evaluate (i) the prevalence of MGUS in patients after liver transplantation (LT), (ii) the role of MGUS as a risk factor for malignancy and other medical complications after LT. One hundred and fifty consecutive patients were included in the study and followed prospectively after LT for more than 18 months. Eighteen patients had MGUS before LT, whereas 49 patients developed MGUS after LT ('de novo' MGUS). Thirty-six of these patients showed a MGUS along all the follow up after LT ('permanent' MGUS). In 31 patients, MGUS disappeared after LT ('transient' MGUS). No patient with MGUS developed B-malignant lymphoproliferative disorder and only one patient developed a myeloma after LT. Comparing patients with 'permanent' MGUS to patients with 'transient' MGUS or without MGUS after LT, the former group showed a higher rate of serious infections (30% versus 13%, P = 0.01), chronic kidney disease (CKD) (75% versus 44%, P = 0.001) and mortality (33% versus 17%, P = 0.04). Permanent MGUS was confirmed as an independent risk factor for serious infections and CKD by multivariate analysis. Permanent MGUS after LT does not entail a significant risk of malignancy, but it is associated with a higher risk of serious infections and CKD.