Nephron hypertrophy and glomerulosclerosis and their association with kidney function and risk factors among living kidney donors

Abstract

Background and objectives The relationship of kidney function and CKD risk factors to structural changes in the renal parenchyma of normal adults is unclear. This study assessed whether nephron hypertrophy and nephron sclerosis had similar or different associations with kidney function and risk factors. Design, setting, participants, & measurements From 1999 to 2009, 1395 living kidney donors had a core needle biopsy of their donated kidney during transplant surgery. The mean non sclerotic glomerular volume and glomerular density (globally sclerotic and non sclerotic) were estimated using the Weibel and Gomez stereologic methods. All tubules were counted in 1 cm2 of cortex to determine a mean profile tubular area. Nephron hypertrophy was identified by larger glomerular volume, larger profile tubular area, and lower non sclerotic glomerular density. Nephro sclerosis was identified by higher globally sclerotic glomerular density. Results The mean (6SD) age was 44612 years, 24-hour urine albumin excretion was 567mg, measured GFR was 103617 ml/min per 1.73 m2, uric acid was 5.261.4 mg/dl, and body mass index was 2865 kg/m2. Of the study participants, 43% were men, 11% had hypertension, and 52% had a family history of ESRD. Larger glomerular volume, larger profile tubular area, and lower non sclerotic glomerular density were correlated. Male sex, higher 24-hour urine albumin excretion, family history of ESRD, and higher body mass index were independently associated with each of these measures of nephron hypertrophy. Higher uric acid, higher GFR, and older age were also independently associated with some of these measures of nephron hypertrophy. Hypertension was not independently associated with measures of nephron hypertrophy. However, hypertension and older age were independently associated with higher globally sclerotic glomerular density. Conclusions Nephron hypertrophy and nephron sclerosis are structural characteristics in normal adults that relate differently to clinical characteristics and may reflect kidney function and risk factors via separate but inter-related pathways.