Nearly all forms of acute glomerulonephritis have a tendency to progress to chronic glomerulonephritis. The condition is characterized by irreversible and progressive glomerular and tubulointerstitial fibrosis, ultimately leading to a reduction in the glomerular filtration rate (GFR) and retention of uremic toxins. If disease progression is not halted with therapy, the net results are chronic kidney disease (CKD), end-stage renal disease (ESRD), and cardiovascular disease. Chronic glomerulonephritis is the third leading cause of CKD, and accounting for about 10% of all patients on dialysis.
The exact cause of CKD in patients with chronic glomerulonephritis may never be known in some patients. Therefore, it has generally been accepted that the diagnosis of CKD can be made without knowledge of the specific cause.
The National Kidney Foundation (NKF) defines CKD on the basis of either of the following:
- Evidence of kidney damage based on abnormal urinalysis results (eg, proteinuria or hematuria) or structural abnormalities observed on ultrasound images
- A GFR of less than 60 mL/min for 3 or more months
In accordance with this definition, the NKF developed guidelines that classify the progression of renal disease into five stages, from kidney disease with a preserved GFR to end-stage kidney failure. This classification includes treatment strategies for each progressive level, as follows:
Stage 1 – This stage is characterized by kidney damage with a normal GFR (≥ 90 mL/min); the action plan consists of diagnosis and treatment, treatment of comorbid conditions, slowing of the progressing of kidney disease, and reduction of cardiovascular disease risks.
Stage 2 – This stage is characterized by kidney damage with a mild decrease in the GFR (60-90 mL/min); the action plan is estimation of the progression of kidney disease.
Stage 3 – This stage is characterized by a moderately decreased GFR (to 30-59 mL/min); the action plan consists of evaluation and treatment of complications.
Stage 4 – This stage is characterized by a severe decrease in the GFR (to 15-29 mL/min); the action plan is preparation for renal replacement therapy.
Stage 5 – This stage is characterized by kidney failure; the action plan is kidney replacement if the patient is uremic.
At the later stages of glomerular injury, the kidney are small and contracted and biopsy results cannot help distinguish the primary disease. Histology and clues to the etiology are often derived from other systemic diseases (if present). Considerable cause-specific variability is observed in the rate at which acute glomerulonephritis progresses to chronic glomerulonephritis.
The prognosis depends on the type of chronic glomerulonephritis (see Etiology). ESRD and death are common outcomes unless renal replacement therapy is instituted.