title: Significant association between renal function and amyloid-positive area in renal biopsy specimens in AL amyloidosis.
abstract: BACKGROUND
  The kidney is a major target organ for systemic amyloidosis that often affects the kidney including proteinura, and elevated serum creatinine (Cr). The correlation between amount of amyloid deposits and clinical parameters is not known. The aim of this study was to clarify correlation the amyloid area in all renal biopsy specimen and clinical parameters.
  
  
  METHODS
  Fifty-eight patients with an established diagnosis of AL amyloidosis participated in the study. All patients showed amyloid deposits in renal biopsies. We retrospectively investigated the correlation between clinical data and amyloid occupied area in whole renal biopsy specimens.
  
  
  RESULTS
  The area occupied by amyloid was less than 10% in 57 of the 58 patients, and was under 2% in 40. For statistical analyses, %amyloid-positive areas were transformed to common logarithmic values (Log10%amyloid). Cr showed significant correlation with Log10%amyloid and estimated glomerular filtration rate (eGFR) showed the significant negative correlation. Patient age, cleatinine clearance (Ccr), blood urea nitorogen, and urinary protein was not significantly correlated with Log10%amyloid. The correlation with other clinical factors such as sex, and serum concentrations of total protein, albumin, immunoglobulins, compliments was evaluated. None of these factors significantly correlated with Log10%amyloid. According to sex- and age- adjusted multiple linear regression analysis, Log10%amyloid had significant positive association with Cr and significant negative association with eGFR.
  
  
  CONCLUSIONS
  There is significant association between amyloid-positive area in renal tissue and renal function, especially Cr and eGFR. The level of Cr and eGFR may be a marker of amount of amyloid in renal tissue.
authors.affiliation: Division of Clinical Nephrology and Rheumatology, Niigata University Graduate School of Medical and Dental Sciences, 1-757 Asahimachi-Dori, Chuo-ku, Niigata City, 951-8510, Japan. kurodat@med.niigata-u.ac.jp
authors.forename: Takeshi
authors.initials: T
authors.lastname: Kuroda
authors.forename: Naohito
authors.initials: N
authors.lastname: Tanabe
authors.forename: Daisuke
authors.initials: D
authors.lastname: Kobayashi
authors.forename: Yoko
authors.initials: Y
authors.lastname: Wada
authors.forename: Shuichi
authors.initials: S
authors.lastname: Murakami
authors.forename: Masaaki
authors.initials: M
authors.lastname: Nakano
authors.forename: Ichiei
authors.initials: I
authors.lastname: Narita
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000682:Amyloid / Q000032:analysis / Q000096:biosynthesis*; D000686:Amyloidosis / Q000175:diagnosis* / Q000503:physiopathology*; D001706:Biopsy; D005260:Female; D006801:Humans; D007668:Kidney / Q000473:pathology* / Q000502:physiology*; D007677:Kidney Function Tests; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D055815:Young Adult
chemical_list: D000682:Amyloid