(I) Mogensen diabetic nephropathy staging
Mogensen divided type 1 diabetic nephropathy into five stages.
1, Stage I glomerular hyperfiltration and renal hypertrophy stage
In the glomerular hyperfiltration or renal hypertrophy stage, the glomerular filtration rate GFR increases and can reach 140% of normal, and the glomerular and renal volume increases along with increased renal blood flow and glomerular capillary perfusion pressure. The above changes are closely related to blood glucose level and can be partially relieved by insulin treatment.
2.Stage II normal albuminuria stage
In the phase of normoalbuminuria, the urinary albumin excretion rate of UAE is still normal, and the glomerular tissue structure is changed, which shows the thickening of glomerular basement membrane GBM and the increase of thylakoid matrix. GFR can be maintained at a high level in this stage, and post-exercise albuminuria is one of the indicators for clinical diagnosis of this stage.
3.Stage III early diabetic nephropathy
In early diabetic nephropathy, the urinary albumin excretion rate is consistently higher than 20-200μg/min, or 30-300mg/24h. The blood pressure of patients in this stage starts to rise, and antihypertensive treatment can reduce urinary albumin excretion. Renal histological changes are further aggravated by GBM thickening and thylakoid matrix increase more obvious, and glomerular nodule-like lesions and glassy degeneration of small renal vessels can appear.
4.Stage IV clinical diabetic nephropathy
Clinical diabetic nephropathy with massive albuminuria and persistent elevated urine protein, clinically manifested as hypertension and nephrotic syndrome. Some patients are accompanied by mild microscopic hematuria, with typical K-W and its GFR significantly decreased by histological changes in the kidney, and progressive development of renal function damage.
5.Stage V end-stage renal failure
In end-stage renal failure, once the patient enters stage IV, the disease tends to develop progressively, if not actively controlled. The renal GFR will decline at an average rate of 1 ml/min per month until it enters renal failure and the corresponding symptoms of uremia and its comorbidities appear clinically.
The Mogensen diabetic nephropathy staging described above is, to some extent, also applicable to type 2 diabetic nephropathy. However, type 2 diabetic nephropathy has reached at least stage III by the time the clinical diagnosis is established.
(ii) Greek internal medicine diabetic nephropathy staging
Greek internal medicine classifies diabetic nephropathy into three stages.
1. Early diabetic nephropathy
Increased glomerular filtration rate (GFR), hypertrophy of renal units, increased kidney volume, and the presence of microalbuminuria are characteristic changes of early diabetic nephropathy. Patients lack clinical signs and symptoms of glomerular lesions.
Definition of microalbuminuria, urinary albumin excretion rate (UAE) in the range of 20-200 μg/min, or 30-300 mg/24h is called microalbuminuria. Effective intervention at this stage can hopefully stop the progression to massive albuminuria and slow down its progression. If a patient develops microalbuminuria, the urinary albuminuria excretion rate should be repeatedly checked twice over a period of 6 months. If both show microalbuminuria, the diagnosis of early diabetic nephropathy is established and active treatment should be given. If the patient has only microalbuminuria once, the urinary albumin excretion rate should be tested regularly.
2.Clinical stage diabetic nephropathy
Clinical stage diabetic nephropathy is diagnosed when the urinary albumin excretion continuously exceeds 200μg/min or the routine urinary protein quantification exceeds 0.5g/24h. The patient has a progressive decline in renal function and develops hypertension. In patients with large amounts of proteinuria, the clinical diagnosis of diabetic nephropathy must carefully exclude other possible causes of proteinuria, in addition to the fact that diabetic nephropathy usually does not have severe hematuria. According to foreign reports, the incidence of type 2 diabetic nephropathy combined with other primary kidney diseases is about 23%.
3.Advanced diabetic nephropathy
Patients develop azotemia, hematoma and hypertension aggravation. If blood pressure and blood glucose levels cannot be effectively controlled, GFR will decrease at an average rate of 1 ml/min per month. Patients entering this stage have decreasing GFR levels, while proteinuria often persists, making hypoproteinemia worse.
In patients with renal failure, a more pronounced hyperkalemia will generally occur when GFR drops to 15-20 ml/min. In some patients with diabetic nephropathy, pronounced hyperkalemia will occur when GFR is at the level of 20-40 ml/min, and hyperkalemic hyperchloremic acidosis, which is a manifestation of type IV renal tubular acidosis, will occur. Most patients with these changes are accompanied by hyporenin and hypo aldosteronism.