Clinical Analysis Of Patients With Non-malignant Monoclonal Gammopathy And Chronic Kidney Disease

Background and AimPatients with monoclonal gammopathy complicated with chronic kidney disease can be diagnosed as malignant hematological disease such as multiple myeloma or lymphoma,or be diagnosed as benign hematological disease such as monoclonal gammopathy of renal significance(MGRS)or monoclonal gammopathy of undetermined significance(MGUS).MGRS refers to nonmalignant small B cell clones which produce nephrotoxic monoclonal protein.Different from MGUS,MGRS is associated with increased morbidity and mortality.MGRS-associated nephropathies are progressive and recur quickly even after kidney transplantation.The patients with systematic AL amyloidosis often die from cardiac complications before the loss of renal function.A series of studies have shown that if patients with MGRS are diagnosed early and treated to eradicate the serum monoclonal protein,the loss of renal function become slower and patients survive longer.Patients who present with higher creatinine and do not response to therapies progress to ESRD quickly.As a result,differentiating MGRS from MGUS is crucial among patients with nonmalignant monoclonal gammopathy complicated with chronic kidney disease.Renal biopsy is the only means for the differential diagnosis.Our study aims to explore the prevalence and characteristics of MGRS among patients with monoclonal gammopathy complicated with chronic kidney disease,providing guidance in clinical practice so as to reduce the possibilities of misdiagnosis.MethodsPatients diagnosed as nonmalignant monoclonal gammopathy complicated with chronic kidney disease from January 1st,2002 to December 1st,2020 in Nanfang Hospital were included.The clinical data such as age、serum creatinine、urine protein excretion、the type of paraprotein、the results of bone biopsy were recorded.For patients who underwent renal biopsy,we recorded the renal pathology.For patients who did not,we recorded the reasons of deferring a kidney biopsy.ResultIn total,we selected 180 patients with non-malignant monoclonal gammopathy complicated with renal insufficiency,among which 100 patients had renal biopsy.Of the 100 patients,59.0%were diagnosed as MGRS.AL amyloidosis is the most common renal pathology,accounting for 72.9%of all lesions,followed by proliferative glomerulonephritis with monoclonal protein deposit.Among 180 patients,14 patients with diabetes mellitus underwent renal biopsy,only 14.2%of whom were diagnosed as MGRS.And diabetic nephropathy was the most frequent lesion.We did not find differences between patients diagnosed as MGRS and patients diagnosed as non-MGRS in the concentration of serum creatinine as well as the urine protein excretion.The possibility of identifying MGRS is increased when the serum/urine light chain ratio is abnormal.Among patients who did not undergo renal biopsy,26.3%of the patients could not be diagnosed due to shrinkage of kidney.ConclusionAmong patients with non-malignant monoclonal gammopathy complicated with renal insufficiency,59.0%were diagnosed as MGRS.AL amyloidosis is the most common renal pathology,followed by proliferative glomerulonephritis with monoclonal protein deposit.The possibility of identifying MGRS is increased when the serum/urine light chain ratio is abnormal.