A clinical evaluation of renal amyloidosis in the Japan renal biopsy registry: a cross-sectional study

Background and aim

The available clinical data are limited in a rare glomerular disease, renal amyloidosis. We aimed to clarify the clinical features of renal amyloidosis from database of the Japan Renal Biopsy Registry (J-RBR).

Methods

We performed a cross-sectional study with database of the J-RBR of the Japanese Society of Nephrology. We identified 281 cases of renal amyloidosis from 20,997 cases enrolled into the J-RBR from 2007 to 2014. Systolic blood pressure (SBP) and diastolic blood pressure (DBP) were compared among the levels of ages, amount of urine protein excretion (AUPE) or CKD G stages.

Results

The prevalence of renal amyloidosis was 1.3 % (281/20,997). DBP significantly decreased in higher age quartiles (P = 0.034). SBP and DBP did not increase in the progression of AUPE levels and CKD G stages. In multiple regression analysis, eGFR was a significant independent factor for SBP in all cases and a subgroup without hypertensive agents. There was a reverse significant relationship between SBP and eGFR.

Conclusion

Blood pressure did not significantly increase in elderly and much proteinuric condition in renal amyloidosis. The progression of CKD and decrease of eGFR did not produce the higher SBP. The mechanism underlying these results remains unclear; however, they are unique features of renal amyloidosis. The couple of hypotensive and hypertensive conditions might produce no relationship between blood pressure and CKD stages.