NDT Advance Access published online on March 18, 2009
Nephrology Dialysis Transplantation, doi:10.1093/ndt/gfp116
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Nephron number and individual glomerular volumes in male Caucasian and African American subjects
1 Department of Anatomy and Developmental Biology, School of Biomedical Sciences, Monash University, Victoria 2 Centre for Chronic Diseases, The University of Queensland, Brisbane, Australia 3 Department of Pathology, University of Mississippi Medical Center, Jackson, MS, USA
Correspondence and offprint requests to: Monika A. Zimanyi; E-mail: monika.zimanyi{at}med.monash.edu.au
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Abstract |
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Background. Glomerular hypertrophy has been described in several populations at high risk of chronic kidney disease. Total nephron (and thereby glomerular) number (Nglom) varies widely in normal adult human kidneys and is generally inversely correlated with mean glomerular volume (Vglom). However, little is known about the range of individual glomerular volumes (IVglom) within single human kidneys and the association with Nglom. The aim of the present study was to estimate IVglom in Caucasian and African Americans and identify any associations between heterogeneity in IVglom and nephron number.
Methods. Using unbiased stereological techniques, IVglom was determined for 30 glomeruli in each of 24 adult male kidneys from Jackson, MS, USA (12 Caucasian and 12 African American). Half of each group had ‘high’ Nglom (>1.2 million nephrons per kidney) and the other half had ‘low’ Nglom (<600 000).
Results. Caucasians with high Nglom had a relatively homogeneous distribution of IVglom as well as a relatively low mean value, while those with low Nglom had much greater heterogeneity of IVglom, as well as a larger IVglom (P < 0.0001) compared with those with high Nglom. This disparity was not apparent in African Americans, however, where subjects with both high and low Nglom showed substantial heterogeneity in IVglom and larger mean values (P = 0.95).
Conclusions. High Nglom appeared to protect against glomerular enlargement and volume heterogeneity in Caucasians. However, substantial variation in IVglom and net enlargement in glomerular size in African Americans with high nephron numbers suggest that additional forces, independent of low Nglom, are driving glomerular enlargement and heterogeneity.
Keywords: African American; Caucasian; glomerular volume; nephron number; stereology
Received for publication: 29. 7.08
Accepted in revised form: 25. 2.09