Monoclonal gammopathy of undetermined significance coexisting in patients undergoing kidney transplantation does not adversely influence post-graft clinical outcome

Monoclonal Gammopathy of Undetermined Significance Diagnosed by Persistent Anemia Following Living Kidney Transplantation: A Case Report

The prevalence of monoclonal gammopathy of undetermined significance increases with age, and there may be undiagnosed patients among kidney transplant recipients. A 69-year-old woman underwent ABO-incompatible living-donor kidney transplantation. Her renal function improved immediately postoperatively. Her hemoglobin level gradually increased to 10.5 g/dL at 3 months postoperatively but gradually decreased to 7.3 g/dL at 9 months postoperatively. We administered an erythropoiesis-stimulating agent and consulted the Department of Hematology. Bone marrow aspiration revealed that the pathological monoclonal plasma cells constituted 4.6% of bone marrow cells. Immunoelectrophoresis identified serum monoclonal proteins as immunoglobulin G lambda. The patient was diagnosed with monoclonal gammopathy of undetermined significance, and free light-chain measurements were performed regularly. No disease progression was observed. The anemia improved with the administration of an erythropoiesis-stimulating agent. Monoclonal gammopathy of undetermined significance should be explored as a cause of persistent anemia after kidney transplantation.

Monoclonal gammopathy of unknown significance in kidney transplanted patients: novel insights into long-term outcomes

BACKGROUND

Because of increased access to kidney transplantation in elderly subjects, the prevalence of monoclonal gammopathies of unknown significance (MGUS) in kidney transplantation (KT) is growing. However, little is known about the consequences of MGUS on long-term outcomes.

METHODS

We identified 70 recipients with MGUS present at transplantation (KTMG) and 114 patients with MGUS occurring after KT (DNMG), among 3059 patients who underwent a KT in two French kidney transplantation centers. We compared outcomes of KTMG with those of matched controls.

RESULTS

Baseline characteristics were similar except for an older age in KTMG compared with the DNMG group (62 vs 57 years, P = .03). Transient MGUS occurred more frequently in DNMG patients (45% vs 24%, P = .007). When compared with matched controls without MGUS, KTMG patients showed higher frequency and earlier post-transplant solid cancers (15% vs 5%, P = .04) and a trend for more bacterial infections (63% vs 48%, P = .08), without difference regarding patient and graft survival, rejection episodes or hematological complications. KTMG patients with an abnormal kappa/lambda ratio and/or severe hypogammaglobulinemia at the time of KT experienced shorter overall survival.

CONCLUSIONS

MGUS detection at the time of KT is neither associated with a higher occurrence of graft rejection, nor adversely affects graft or overall survival. MGUS should not contraindicate KT. However, MGUS at the time of KT may be associated with higher risk of early neoplastic and infectious complications and warrants prolonged surveillance. Measurement of serum free light chain should be performed before transplant to refine the risk evaluation of KTMG patients and propose personalized follow-up and immunosuppression.