Diabetes: To Biopsy or not to Biopsy – Part 2

543 0
In my experience the
appetite to biopsy patients with clinical renal disease varies widely between
clinician, institution and country. This is most apparent when it comes to the
diabetic patient with renal disease. In my opinion there is a fear among nephrologists
of biopsying patients with potential diabetic nephropathy (DN). Of course there are clinical features
that increase the likelihood that a diabetic with renal disease has DN.
Retinopathy in a type 1 diabetic, longstanding DM and progressive proteinuria
over years preceding an elevated creatinine. However, the role of microalbuminuria
and proteinuria in predicting CKD progression and the traditional course of
rising albuminuria in DM1 has been challenged. In DM type 2 the picture is less
clear and these patients frequently have many comorbidities. Gearoid posted on
this subject about a year ago now. In CJASN (October) Sharma et al from
Columbia University reviewed the characteristics and renal diagnoses in 620
diabetics who had a renal biopsy. Over 90% had type 2 diabetes. In Columbia
in 2011 approximately ¼ of all biopsies were on patients with diabetes. The results of this
retrospecive review were that 37% of patients had DN alone, 36% had non-diabetic
renal disease (NDRD) alone, and 27% had DN plus NDRD.

In NDRD alone: FSGS (22%), hypertensive nephrosclerosis
(18%), acute tubular necrosis (ATN) (17%), IgA nephropathy (11%), membranous GN
(8%), and pauci-immune GN (7%) comprised 80% of diagnoses.
In DN plus NDRD: ATN (43%), hypertensive nephrosclerosis
(19%), FSGS (13%), and IgA nephropathy (7%).
In multivariate analysis longer duration of DM was
associated with a greater likelihood of DN and less likelihood of NDRD.
The table illustrates the features of patients at the time
of biopsy. Older age, having DM2 vs DM1, short duration of DM and less proteinuria
are more likely in those with NDRD alone vs DN alone in this cohort. 
I think this study highlights the importance of considering
biopsy in diabetics (especially type 2). I would be interested to hear about
the experience of others with respect to biopsy in diabetics.

Posted by Andrew Malone

Characteristics
DN
Alone
DN
Plus NDRD
NDRD
Alone
Participants
(n)
227
164
220
Age
(yr)
59
(49–65)
63
(55–72)
63
(54–70)
Male
sex
129
(56.8)
100
(61.0)
142
(64.6)
Race
Unknown 
108
(47.6)
57
(34.8)
104
(47.3)
White 
62
(27.3)
63
(38.4)
70
(31.8)
African
American 
39
(17.2)
33
(20.1)
29
(13.2)
Hispanic 
12
(5.3)
7
(4.3)
8
(3.6)
Asian 
4
(1.8)
4
(2.4)
7
(3.2)
Other 
2
(0.9)
0
(0.0)
2
(0.9)
DM
type 1
9
(4.0)
5
(3.1)
2
(0.9)
Duration
of DM (yr)
13
(8–17)
10
(7–18)
5
(3–10)
Serum
creatinine (mg/dl)
2.3
(1.6–3.8)
3.1
(1.7–5.2)
2.3
(1.5–4.4)
eGFR
(ml/min per 1.73 m2)
31.3
(17.5–55.2)
21.4
(12.5–46.6)
32.5
(14.3–60.0)
Proteinuria
(g/d)
5.0
(2.8–8.8)
5.0
(2.0–8.0)
2.9
(1.4–7.1)

Leave a Reply