Korbet SM, Rosangela MG, Borok RZ, Schwartz MM
The racial prevalence of glomerular lesions in nephrotic
Am J Kidney Dis
(May) 27:647-651 1996
A retrospective review of the renal biopsies of adult patients with
nephrotic range proteinuria from 1975 to 1994 at Rush-Presbyterian-St.
Luke's Medical Center was performed. Of the 1369 biopsies performed during
this time, there were 340 biopsies in which there was > 3.0 gm of
proteinuria per 24 hours with no evidence of a secondary cause of nephrotic
syndrome. The racial distribution of this group of patients was 50% white,
36% black, 7% other and 7% unknown. Membranous glomerulonephritis was
present in 33% of biopsies, significantly more in white patients than
blacks. Focal segmental glomerular sclerosis was present in 34% of biopsies
and was four times as likely to occur in blacks than in whites. Though
FSGS was a major cause of nephrotic syndrome in black patients > 45 years,
its prevalence was significantly less than in the younger patients.
Overall minimal change disease accounted for 16% of the total biopsies;
however, the incidence decreased from 25% to 11% when comparing the first
nine and the last nine years of this study. During this period of time the
incidence of FSGS increased from 29% to 38%. After 1985 this was
accounted for primarily by black patients. The incidence of other
glomerular lesions in the study was: membranoproliferative
glomerulonephritis - 6%, IgA nephropathy - 7% and immunotactoid
glomerulopathy - 4% of biopsies.
Comment: The authors pointed out that their study supports previous
demonstrating that FSGS is the most common cause of nephrotic syndrome in
black patients. Speculation as to the cause of this increased incidence of
FSGS included a genetic predisposition, the possibility of reduced nephron
mass in comparison to white patients with a higher prevalence of
hypertension, or an increase in the collapsing variant of FSGS. Treatment
of FSGS frequently requires long courses of steroid therapy in contrast to
patients with membranous glomerulonephritis which often undergoes
spontaneous remission. This underscores the importance of renal biopsy in
prognosis and treatment of all patients with idiopathic nephrotic syndrome.
This article up-dates information regarding the incidence of types of
primary glomerular lesions in idiopathic nephrotic syndrome in adults and
points out important changes in the patterns of incidences among races.
(N. Kevin Krane, M.D., Tulane University)