Glomerular Density in Biopsy-Proven Hypertensive Nephrosclerosis

Abstract

Background: Previous autopsy studies suggested that a reduced nephron number is associated with increased risk of hypertension and chronic kidney disease. However, the significance of the nephron number estimated from a renal biopsy in patients with hypertensive nephrosclerosis (HNS) has not yet been elucidated. Methods: In this cross-sectional study, we examined the clinicopathological findings of biopsy-proven HNS patients with preserved renal function (estimated glomerular filtration rate ≥ 60ml/min/1.73 m2). The glomerular density (GD; the number of glomeruli per total renal cortical area) in biopsy specimens was evaluated as a surrogate of the nephron number. Renal biopsies from kidney transplant donors were used as healthy controls. Results: A total of 58 HNS patients were enrolled. The GD value in the HNS patients was low compared with those in the kidney transplant donors (2.0 vs. 3.2/mm2). These differences remained significant when globally sclerotic glomeruli were included in the calculation of the GD. Of note, the GD in HNS patients with overt proteinuria (≥1g/day) was significantly lower than that of HNS patients with mild proteinuria (<1g/day; 1.8 vs. 2.2/mm2, P = 0.014). In contrast, other histopathological parameters, including the severity of global glomerulosclerosis, interstitial fibrosis/tubular atrophy and arterial and arteriole lesions were comparable between the 2 HNS subgroups. In addition, the GD was identified as a factor that was associated with the amount of urinary protein excretion at biopsy, independent of other clinicopathological factors. Conclusions: These results suggest that a low GD is a renal histological characteristic of HNS patients, especially those with overt proteinuria.