Download Nephrotic syndrome in patients with diabetes mellitus is not always

Nephrol Dial Transplant (2001) 16 wSuppl 6x: 86–87
Diabetes Mellitus and the Kidney
Nephrotic syndrome in patients with diabetes mellitus
is not always associated with diabetic nephropathy
R. Kveder1, M. Kajtna-Koselj1, T. Rott2 and A. F. Bren1
University Medical Center, 1Department of Nephrology, Medical Faculty and 2Institute of Pathology,
Ljubljana, Slovenia
Introduction
While in type 1 diabetes mellitus of long duration
(P10 years) severe proteinuria is almost always
related to a well-defined pattern of diabetic nephropathy, type 2 diabetic nephropathy may be the consequence of some non-diabetic form of renal disease
w1,2x. The diagnosis of diabetic nephropathy is more or
less always based on clinical grounds. A long history of
diabetes, evidence of target organ damage (retinopathy), and proteinuria preceding the decline in renal
function are the necessary clues to the diagnosis in
type 1 diabetes. In type 2 diabetes, proteinuria is less
specific than in type 1. A short interval between onset
of diabetes (-5 years), and a lack of retinopathy or
autonomic neuropathy raise the suspicion of the
existence of a non-diabetic renal disease, and warrant
the consideration for renal biopsy w3,4x. Glomerulonephritis in type 2 diabetes was found in about 10 w1x to
25% w2x of cases. The main reasons for the described
differences in the incidence of non-diabetic glomerulopathy in the reported series are the diverse patterns
of patient selection.
Non-diabetic renal disease in patients
with type 2 diabetes mellitus
Recently, very interesting studies in type 2 diabetes,
based on unbiased indications for kidney biopsy in
microalbuminuric and macroalbuminuric patients, with
and without retinopathy have been published w5–7x. In
a cohort study of 53 microalbuminuric patients with
type 2 diabetes, Brocco et al. described normal or
near normal findings in 41% of biopsies (59% of these
Correspondence and offprint requests to: Radoslav Kveder, University
Medical Center, Department of Nephrology, Zaloška 7, 1000
Ljubljana, Slovenia.
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patients had no retinopathy). In 33% of the biopsies
only interstitial changes were present. A typical
diabetic nephropathy was present in 26%; all these
patients had retinopathy w5x. In 36 hypertensive
albuminuric patients with renal insufficiency (serum
creatinine between 133 and 256 mmolul) Schwartz
et al. described non-diabetic glomerular changes in
only 6% w6x. Cordonnier et al. found non-specific
vascular and glomerular changes in 15% of 26 patients
with albuminuria from 70 to 4210 mgu24 h w7x. In
a recent report, on a cohort of 93 persistent macroalbuminuric patients with type 2 diabetes without
retinopathy Christensen et al. w8x, evaluated the cause
of renal disease and collected potential demographic,
clinical, and laboratory data that may help to separate
diabetic from non-diabetic nephropathy. Biopsies
revealed diabetic nephropathy in 69%. In the other
31%, non-diabetic glomerulopathy such as glomerulonephritis (13%) or normal glomerular structure
(18%) was found. Differentiation between diabetic and
non-diabetic glomerulopathy was not possible on
demographic, clinical, or laboratory data w8x.
Recently we launched a study of our diabetic
patients with type 2 disease without retinopathy who
presented with macroalbuminuria or clinical nephrotic
syndrome. Up until now, 76 patients in whom a kidney
biopsy was performed between 1987 and March 2001
because of suspicion of non-diabetic renal disease were
included in this study. Preliminary analysis has shown
that 17 patients (22%) had typical diabetic nephropathy, 21 patients (28%) had combined diabetic and
non-diabetic glomerulopathy, and 37 patients (49%)
had only non-diabetic glomerulopathy. Eighteen
patients had full-blown nephrotic syndrome at the
time of investigation. In the latter group, five patients
(28%) had isolated diabetic nephropathy (serum
creatinine 148–526 mmolul). Combined nephropathies
were found in nine patients (50%): in four patients
diabetic nephropathy was combined with IgA nephropathy, in another two patients pathological features
of Henoch–Schoenlein’s purpura were present, and
2001 European Renal Association–European Dialysis and Transplant Association
Nephrotic syndrome is not always associated with diabetic nephropathy
a different glomerulopathy was described in the
remaining three patients. Interestingly, male sex prevailed in this subgroup (8u9). Eight patients presented
also with renal dysfunction (average serum creatinine
in this group 239 mmolul, range 92–526 mmolul). Pure
non-diabetic glomerulopathy was found in four nephrotic patients (22%) with type 2 diabetes: two presented
with membranous nephropathy, and two with minimal
change nephropathy (unpublished data).
It is useful to compare these preliminary findings
with the results of other studies. But some similarities
as well as discrepancies with already mentioned studies
as well as with some other reports w9–14x make these
observations interesting enough to continue.
Conclusions
There is no doubt that non-diabetic renal disease in
patients with type 2 diabetes is highly prevalent. What
is not clear at this time is the statement of some
authors that kidney biopsy should be performed in all
patients with suspected non-diabetic renal involvement, especially with macroalbuminuria. In favour
of this approach is the fact that knowledge of the
underlying cause of proteinuria may play an important
role in planning the correct treatment of these patients.
Another important fact in favour of performing a
biopsy is the scarcity of other means, besides kidney
biopsy, to differentiate diabetic from non-diabetic
glomerulopathy. On the other hand, specific treatment
of non-diabetic renal disease in known diabetic patients
is seldom applied. But when a patient with type 2
diabetes without retinopathy or autonomic neuropathy
has a nephrotic syndrome then there is no doubt that
kidney biopsy should be performed.
87
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