Clinical Outcome of Immunoglobulin Light Chain Amyloidosis Affecting the Kidney

Abstract

Introduction: The kidney is affected by immunoglobulin light chain amyloidosis (AL) in more than 50% of patients who present with the disease, but long-term predictors for and outcomes after renal replacement therapy have not been well described in this patient groupPatients: 145 patients with AL who participated in Mayo Clinic treatment trials and were monitored for at least 11 years. No patient was lost to follow-upResults: Among patients presenting with renal AL, 42% ultimately received renal replacement therapy compared with 5% of patients who did not have an initial presentation involving the kidney.Table 1. Monoclonal Protein Studies in 145 Patients With Immunoglobulin Light Chain AmyloidosisaPatients, No. (%)Monoclonal ProteinRenal Amyloid at Presentation (n=84)Nonrenal Amyloid at Presentation (n=61)None7 (8)2 (3)k6 (7)12 (20)l71 (85)47 (77)aP=.02 l more likely to cause renal presentationTable 2. Characteristics of All 145 Patients With Immunoglobulin Light Chain AmyloidosisAmyloidRenal (n=84)Nonrenal (n=61)P ValueAge, median (IQR), y61 (52–67)62 (55–68).47Sex, male/female52/3240/21.7224-hr urine protein loss, median (IQR), g/d7.0 (4.4–11.7)0.3 (0.1–6.4)NAaCreatinine, median (IQR), mg/dL1.1 (0.9–2.2)1.1 (0.9–1.3).22Cardiac involvement (yes/no)35/4848/16.0001Abbreviations: IQR, interquartile range; NA, not applicable.a included in the definition of renal amyloidosisPatients with l immunoglobulin light chain amyloid were significantly more likely to have renal involvement and had significantly greater urinary protein loss than patients with κ or no monoclonal light chain amyloidTable 3 Distribution of Urinary Protein and Creatinine Based on Monoclonal ProteinMonoclonal ProteinTestk (n=18)l (n=118)None (n=9)P ValueAll patients (N=145)24-hr urine protein loss, median (IQR), g/d0.73 (0.16–2.37)3.61 (0.35–7.8)5.68 (0.3–12.2).001Creatinine, median (IQR), mg/dL1.1 (0.9–1.3)1.1 (0.9–1.3)1.5 (1.2–1.6)NSPatients with renal amyloid at presentation (n=84)24-hr urine protein loss, median (IQR), g/d2.93 (1.1–5.0)7.2 (4.8–11.8)7.8 (3.8–12.6).04Creatinine, median (IQR), mg/dL1.0 (0.8–2.6)1.1 (0.9–2.2)1.5 (1.1–1.6)NSAbbreviation: IQR, interquartile range.Patients with renal amyloid who ultimately received dialysis support had significantly higher serum creatinine and 24-hour urine protein levels at presentation. Absence of cardiac involvement at diagnosis predicted an increased likelihood of dialysisTable 4 Characteristics of 84 Patients Presenting With Renal AmyloidosisDialysisSubsequentlyNot RequiredCharacteristicRequired (n=35)(n=49)P ValueAge, median (IQR), y60 (52–67)62 (52–67).90Sex, male/female21/1431/18.7624-hr urine protein loss, median (IQR), g/d7.4 (5.0–14.8)5.9 (3.7–9.1).03Creatinine, median (IQR), mg/dL1.4 (0.9–2.8)1.1 (0.9–1.5).01Cardiac involvement (yes/no)9/2626/23.01Abbreviation: IQR, interquartile range.The median time from diagnosis to dialysis was 29.5 months for those that went into renal failure.). However, the actuarial risk reached 50% at 12 yearsKaplan-Meier failure curve demonstrating the actuarial time from diagnosis to the start of dialysis therapy N=145For 38 patients who received dialysis, median survival from day 1 of dialysis was 10.4 monthsKaplan-Meier survival of 38 patients from the start of dialysis therapyConclusion: In our study, 26% of all patients with AL ultimately received renal replacement therapy compared with 42% of patients who presented with renal AL specifically. The presenting 24-hour urine protein loss and creatinine values predict which patients will require dialysis. Median survival for patients starting dialysis is less than 1 year. Presence of l light chain amyloid predicts an increased likelihood of renal involvement and, when the kidney is affected, increased proteinuria.