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Open Access Research article

Significant association between renal function and amyloid-positive area in renal biopsy specimens in AL amyloidosis

Takeshi Kuroda1*, Naohito Tanabe2, Daisuke Kobayashi1, Yoko Wada1, Shuichi Murakami1, Masaaki Nakano3 and Ichiei Narita1

Author Affiliations

1 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

2 Department of Health and Nutrition, Faculty of Human Life Studies, University of Niigata Prefecture, 471 Ebigase, Higashi-ku, Niigata, 950-8680, Japan

3 Department of Medical Technology, School of Health Sciences, Faculty of Medicine, Niigata University, 2-746 Asahimachi-Dori, Chuo-ku, Niigata City, 951-8518, Japan

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BMC Nephrology 2012, 13:118  doi:10.1186/1471-2369-13-118

Published: 24 September 2012

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.

Conclusion

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.

Keywords:
AL amyloidosis; Amyloid-positive area; Creatinine clearance; Estimated GFR; Renal function