Clinical analysis of renal function in primary systemic amyloidosis

Objective There is little knowledge about whether or not tubular injury occurs in primary systemic amyloidosis(AL) that involves kidney.This study analyzed the laboratory data on renal function in AL,to explore their clinical significances.Methods From January 2004 to May 2010,49 patients with AL were histologically diagnosed by renal and/or intestinal biopsy in our department.Multiple myelomas were excluded and all were considered multiple organs involved.These patients were divided into two groups,normal renal function and renal dysfunction groups.Clinical and laboratory data were compared between them.The correlations of urinary retinol binding protein(RBP) with serum creatinine(Scr),clearance of creatinine(Ccr),serum albumin,blood urea nitrogen(BUN),urine protein and urine light chains were further analyzed.Results There was no significant difference in clinical features such as sex and age between the two groups.The laboratory data except glomerular filtration rate(GFR) and urinary RBP in the two groups were similar.Compared with patients in normal renal function group,patients in renal dysfunction group had lower GFR but higher RBP.Urinary RBP correlated with Scr,Ccr,Serum albumin and BUN,but not with urine protein and urine light chains.Urinary RBP related positively to the level of Scr(r=0.6342,P0.0001) and related negatively to the level of Ccr(r=-0.6766,P0.0001).Conclusion Tubular injury accompanies glomerular damage in AL amyloidosis.Urinary RBP might be a good marker of renal dysfunction in AL patients.