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Doctor Boris ZINGERMAN
Nephrolog

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Diffuse changes in the parenchyma and sinuses of the kidneys: what is it?

 
, medical expert
Last reviewed: 22.11.2021
 
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Explaining to patients what diffuse changes in the kidneys, detected during their ultrasound scan (US), mean, nephrologists and urologists talk about echographically visualized pathological abnormalities in the tissues and individual structures of this organ. Such pathomorphological signs are found in many renal diseases, as well as diseases that give nephrological complications.

Therefore, the information obtained is very important for correct diagnosis and adequate treatment. [1]

Causes of the diffuse kidney changes

The key causes of diffuse changes in the parenchyma of the kidneys, interstitial tissue of their stroma, cortical and medullary (medullary) substance, sinuses, Malpighian pyramids or tubular (tubular) structures of nephrons in the majority of cases are associated with nephrological diseases:

Similar changes are observed in renal tuberculosis, in arterial hypertension (leading to renovascular hypertension and nephrosclerosis), in  diabetic nephropathy .

Diffuse kidney changes in children revealed by ultrasound are also the result of pathological processes caused by nephrological, metabolic or autoimmune diseases. Read more in publications:

In cases of congenital  anomalies of the structure of the renal parenchyma , such as hereditary polycystic disease (multicystic dysplasia of the kidneys) and spongy kidney, with neonatal and infant hydronephrosis, with diffuse nephroblastomatosis, as well as with  hereditary tubulopathies  (lesions of the renal tubules), ultrasonography of the kidney may show the existing diffuse renal changes child. [2]

Risk factors

Factors that can increase your risk of diffusely altered chronic kidney disease include:

  • hereditary predisposition (the presence of nephrological diseases in a family history);
  • diabetes;
  • high blood pressure;
  • rheumatoid arthritis;
  • gout and impaired nitrogen metabolism;
  • systemic lupus erythematosus (SLE);
  • systemic scleroderma;
  • multiple myeloma;
  • hepatitis of autoimmune etiology;
  • protein metabolism disorders - amyloidosis (types AA and AL);
  • hemorrhagic vasculitis;
  • hyperparathyroidism;
  • tuberculosis;
  • kidney injury with violation of their structure;
  • invasion by echinococcus larvae;
  • long-term use of certain medications (pain relievers, antibacterial, non-steroidal anti-inflammatory, diuretic);
  • immune deficiency;
  • smoking, alcoholism, drug addiction.

Pathogenesis

Such a pathomorphological sign as diffuse changes in the kidneys is recorded by sonography as a fact indicating disorders that cause the pathogenesis of specific diseases.

For example, in many types of nephritis or pyelonephritis, the mechanism for the appearance of diffuse changes consists in the infiltration of parenchymal cells and interstitial tissue of the kidneys by leukocyte monocytes and tissue macrophages (most active during inflammation) and subsequent alteration in the form of focal or continuous transformation of functional cells into fibrous tissue. Also see -  Pathogenesis of interstitial nephritis

In patients with lupus, nephritis develops with damage to functional structures and segmental fibrosis of kidney tissues due to the effect on the cell membranes and basement membranes of the walls of the renal capillaries of human antiphospholipid immunoglobulins (autoantibodies). [3]

Dysfunction of  kidney nephrons  in glomerulosclerosis is the result of aggravating hypertrophy of filtering glomeruli (glomeruli).

In the complex biochemical mechanism of diabetes-induced kidney damage, which clinical statistics claim occurs in a third of patients, elevated blood sugar (hyperglycemia) plays a major role. Under the influence of excess glucose, the post-translational modification of membrane proteins of kidney cells is activated, which undergo glycosization with a violation of their structure. And the simultaneous hyperactivity of protein kinase enzymes, affecting cellular metabolism, increases the toxicity of free radicals.

Diffuse changes in the liver, pancreas and kidneys in amyloidosis are explained by extracellular fibrous deposits of insoluble amyloid protein in the tissues of these organs. In the kidneys, this protein accumulates in the filtering structures of the nephrons, which is why nephrotic syndrome develops.

See also -  Pathogenesis of chronic renal failure

Symptoms of the diffuse kidney changes

Can patients feel the symptoms of diffuse kidney changes - as characteristic manifestations of the disease or its first signs?

As noted above, these pathological changes are detected during instrumental diagnostics - with  ultrasound of the kidneys and ureters , representing diagnostic indicators of a wide range of nephrological diseases or renal complications of other diseases. Of course, diffuse changes in the structure of both kidneys, changes in the left or right kidney - depending on the stage of the pathological process and the degree of its severity - significantly reduce the efficiency of the organ. But this is manifested by the symptomatology of a specific disease. Read more:

Forms

According to the severity of the ultrasound image, chronic diffuse changes in the kidneys, affecting the entire organ or its part, can be weak or indistinct, moderate and pronounced diffuse changes in the parenchyma and other structures are also determined.

According to nephrologists, often diagnostic ultrasound - due to the lack of specificity of hyperechoic images - does not give a specific result, therefore clinical correlation is necessary for its interpretation. What types of diffuse changes can be visualized in specific kidney diseases?

Diffuse changes in the parenchyma of both kidneys - with an increase or decrease in its thickness - can be with inflammation and the development of urolithiasis; with nephrosclerosis and problems with intrarenal vessels; with congenital anomalies, systemic, metabolic and immune-mediated diseases.

In cases of xanthogranulomatous pyelonephritis, renal parenchymal malakoplakia or lymphoma, there may be a one-sided diffuse change in the left kidney or only the right one.

Diffuse changes in the sinuses of the kidneys (renal sinuses with the system of cups and pelvis located in them) may indicate pyelitis and pyelonephritis (when sinus tissues become denser due to inflammation), as well as hydronephrosis (with dilatation of the urine-filled pyelocaliceal structures). With fibrolipomatosis in the sinus area, in the presence of cysts, calculi or tumors, diffuse changes affect both the calyx-pelvic system and the parenchyma of the kidney. [4]

Diffuse changes in the renal stroma (formed by connective tissue) are most often found in cases of its lymphoid and macrophage infiltration in acute and chronic inflammatory diseases (interstitial and tubulointerstitial nephritis, pyelonephritis), in patients with metabolic disorders or due to exposure to the body of viral or exogenous chemical toxins. [5]

Diffuse-focal kidney changes are characteristic of nephrosclerosis, which develops as a result of impaired urine outflow, as well as for chronic pyelonephritis with scar tissue alteration and multiple foci of atrophy.

Diffusely inhomogeneous changes in the kidneys with an increase in their size may be related to polycystic and amyloidosis, and the localization of such changes in the parenchyma is possible in renal tumors of a malignant nature.

Diffuse nonspecific renal changes often accompany their infiltrative lesions (cell infiltration) of inflammatory or tumor etiology. Such changes (with epithelial neoplasms of the renal parenchyma, renal cell or medullary cancer, sarcoma, lymphoproliferative diseases) can enlarge the kidney, but do not have a clear border between the lesion and normal parenchyma. [6]

Complications and consequences

The internal capacity of the kidneys is limited, since the formation of new nephrons is impossible. Potential complications and consequences of diseases in which diffuse changes in the structures and tissues of the kidneys occur can manifest themselves:

  • fluid retention in the body and tissue edema;
  • hyperkalemia (an increase in the level of potassium in the blood), which affects the work of the cardiovascular system;
  • violation of tubular reabsorption of electrolytes;
  • the development of  acute and chronic nephrotic syndrome ;
  • progressive decrease in glomerular filtration rate and deterioration of renal function;
  • uremia and  chronic renal failure requiring peritoneal dialysis;
  • uremic coma ;
  • irreversible kidney damage - up to the terminal stage. [7]

Diagnostics of the diffuse kidney changes

Ultrasound examination is the most important and rather informative part  of kidney examination . Changes in their tissues and structures of a diffuse nature are visualized on the monitor of the ultrasound device in different ways: in the form of anechoic, echo-positive, hypo or hyperechoic formations, areas and areas. [8]

Echoes of diffuse kidney changes evaluated by specialists in ultrasound diagnostics are described using medical terminology and are designed for doctors, not patients. More information in the articles:

However, according to the results of ultrasound of the kidneys, it is impossible to determine the cause of their diffuse changes. Therefore, a complete diagnosis is carried out - taking into account the patient's history and his complaints, using all the methods available today. [9]

First of all, laboratory tests are needed: blood tests for the level of creatinine and urea nitrogen, for antibodies to the anti-phospholipase A2 receptor (PLA2R);

General and biochemical analyzes of urine, daily urine analysis, for protein in urine, for the presence of bacteria in it,  samples for urine concentration  , etc. [10]

If oncology is suspected and in idiopathic nephrological diseases, a histological examination of a tissue sample is required, for which a puncture biopsy of the kidney is performed.

In addition to ultrasound, instrumental diagnostics includes:

Differential diagnosis

Many kidney diseases have nonspecific (similar) symptoms, and only differential diagnosis - based on a complete examination of the patient and consultations with other specialists - makes it possible to make a correct diagnosis.

Who to contact?

Nephrologist

Treatment of the diffuse kidney changes

After identifying diffuse changes, clarifying their cause and determining the exact diagnosis, a complex treatment of the diagnosed diseases is prescribed:

Prevention

Prevention of kidney diseases recommended by experts is the treatment of urinary tract infections, especially chronic ones, as well as ultrasound monitoring of patients with chronic nephrological pathologies.

Forecast

When diffuse changes in the kidneys are detected, the prognosis of their further state may depend only on the course of the diseases that caused them, many of which rapidly progress to functional renal failure, and some, with successful therapy, are capable of partial remission with relapses.

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