Types of chronic renal failure

Classification of chronic renal failure

There are many different classifications of renal dysfunction, developed by domestic and foreign authors and based on different principles. As the latter are: the value of glomerular filtration, the concentration of serum creatinine, a violation of tubular function and the staging of clinical symptoms. In our country there is no single generally accepted classification of renal dysfunction in children.

In terms of the degree of involvement in the pathological process of various departments of the nephron, there are:

• partial chronic renal failure - isolated or combined renal dysfunction;
• total chronic renal failure - a complete symptomatic complex of homeostatic disorders associated with the inclusion in the pathological process of all elements of the nephron;
• terminal chronic renal failure is the final stage of the disease, in which most of the nephrons do not function and the compensatory possibilities of the kidneys are exhausted. GFR at this stage is less than 15 ml / min.

It is important to take into account that the clinical signs of chronic renal failure largely depend on the underlying disease that led to its development. The progression of the disease with the defeat of the glomerular apparatus and the primary involvement in the process of tubulointerstitutions takes place in different ways. From these positions of great interest is the classification of violations of kidney functions in children, proposed by MS. Ignatova et al. (1986), which takes into account the dominant substrate of injury.

Classification of renal dysfunction

Degree of violations	Glomerular apparatus	Tubing apparatus
PNO	No function changes	No function changes
Mon I	Violation of the circadian rhythm of filtration	Disorder of circadian rhythm of tubular functions
Mon. IIa	Compensated and subcompensated filtering faults	Compensated and subcompensated disorders of tubular functions
PN IIb-CRF I	Decompensated violations of filtration and tubular functions	Decompensated violations of tubular functions and filtration
Mon II-CRN III	Total with disruption of homeostasis	More often partial with disturbance of a homeostasis
CRP III-terminal PN	Terminal total	Terminal, more often total

• PN - renal insufficiency;
• CRF - chronic renal failure.

In addition, we can distinguish the classification stages of chronic renal failure, proposed by VI. Naumova (1991).

In the compensated (first) stage, only a decrease in the reserve capacity of the kidneys is noted without disturbing the homeostatic constants.

The subcompensated (second) stage is characterized by unstable hyperazotemia, increased creatinine concentration, and impaired partial renal function.

In the decompensated (third) stage, signs of chronic renal failure are expressed. Terminal (fourth) stage - the final stage of chronic renal failure (uremia). In accordance with the clinical classification, there are 3 stages of chronic renal failure:

• initial (GFR = 40-60 ml / min);
• conservative (GFR = 15-40 ml / min);
• terminal (GFR <1-015 ml / min).

In 2002, the European Association of Nephrologists developed a unified classification of chronic kidney disease, which includes chronic renal failure.

Chronic kidney disease occurs as a result of prolonged (> 3 months) course of any kidney disease. The basis of its classification is the value of GFR, calculated by formulas and not dependent on the collection of daily urine. There are 5 stages of chronic kidney disease.

Classification of chronic kidney disease (NKF / KD0QI, 2002)

Stage	Symptoms	Glomerular filtration rate, ml / min
I	Symptoms of nephropathy (kidney damage and / or microalbuminuria), normal or elevated GFR	290
II	Symptoms of nephropathy (kidney damage and / or microalbuminuria), moderate decline in GFR	60-89
III	Reduction of GFR of medium degree	30-59
IV	Reduction of GFR expressed degree	15-29
V	Terminal Renal Failure	<15

More accurate values of creatinine clearance for the definition of GFR in children are provided by the Schwartz formula (1976):

Creatinine clearance (ml / min) = K x growth (cm) / serum creatinine (mg / dL).

There is another formula:

Creatinine clearance = K x height (cm) x 80 / serum creatinine (μmol / L), where K = 0.55 for all children aged 2 to 12 years and for girls 13 to 18 years. For boys from 13 to 18 years, K = 0.77.

For children, a specific evaluation of kidney function is required, since the normal GFR varies with age, sex, and physical data and increases as the child matures, approaching average adult values by about 2 years of age.

Normal level of glomerular filtration in children and adolescents

Age	Glomerular filtration rate, ml / min
1st week	41115
2-8th week	66 + 25
Older than 8 weeks	96122
2-12 years old	133127
13-21 years (men)	140130
13-21 year (women)	126122