LoginClassification system for leading cause of kidney failure
An international group of medical experts has crafted a much-needed classification system for diabetic nephropathy, the leading cause of total kidney failure, according to a study appearing in an upcoming issue of the Journal of the American Society Nephrology (JASN). The effort should improve communication among health professionals, help researchers design better clinical studies, and guide patient care.
Current estimates suggest that 285 million people worldwide will live with diabetes in 2010 and that the incidence of diabetes will continue to rise. As a result, the incidence of diabetic nephropathy, or kidney damage that arises as a complication of diabetes, will likely increase as well. Diabetic nephropathy is a complex condition with varying degrees of severity and varying effects on the kidneys.
While researchers do not fully understand the mechanisms involved in the development and progression of diabetic nephropathy, they know that too much blood sugar in diabetic patients can damage the clusters of tiny blood vessels in the kidneys that help remove waste from the body. Eventually, the kidney structures begin to leak and kidney failure ensues. Unlike other kidney conditions, diabetic nephropathy has no standard classification system.
Recently, however, a unique cooperative effort among groups of experts from 16 universities spread over seven countries in three continents developed a uniform international classification system that reflects the current understanding of the various forms of diabetic nephropathy. Jan Anthonie Bruijn, MD, PhD (Leiden University Medical Center, the Netherlands), who led the effort, hopes that the classification system will standardize definitions of different classes of diabetic nephropathy and encourage uniform and reproducible reporting of cases among different medical centers.
The new classification system categorises diabetic nephropathy by varying degrees of severity that will be easy to discern in the clinic. The experts divided the condition into four progressive classes, with the first class being the mildest and the fourth class being the most severe. The system may help guide clinicians as they treat affected patients. In addition, it could aid researchers as they continue to search for the mechanisms involved in the development and progression of diabetic nephropathy.
Table 1: Glomerular classification of DN1
| Class | Description | Inclusion criteria |
|---|---|---|
| I | Mild or nonspecific LM changes and EM-proven GBM thickening. | Biopsy does not meet any of the criteria mentioned below for class II, III, or IV. GBM > 395 nm in female and > 430 nm in male individuals 9 years of age and older.a |
| IIa | Mild mesangial expansion. | Biopsy does not meet criteria for class III or IV. Mild mesangial expansion in > 25% of the observed mesangium. |
| IIb | Severe mesangial expansion. | Biopsy does not meet criteria for class III or IV. Severe mesangial expansion in > 25% of the observed mesangium. |
| III | Nodular sclerosis (Kimmelstiel-Wilson lesion). | Biopsy does not meet criteria for class IV. At least one convincing Kimmelstiel-Wilson lesion. |
| IV | Advanced diabetic glomerulosclerosis. | Global glomerular sclerosis in > 50% of glomeruli. Lesions from classes I through III. |
LM, light microscopy
aOn the basis of direct mesurement of GBM width by EM, these individual cutoff levels may be considered indicative when other GBM measurements are used.
1Table reproduced from Tervaert TW, Mooyaart AL, Amann K, Cohen AH, Cook HT, Drachenberg CB. Pathologic classification of diabetic nephropathy. J Am Soc Nephrol. 2010 Feb 18. [Epub ahead of print].
(Source: American Society of Nephrology: Journal of the American Society Nephrology: March 2010)
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