Glomerulonephritis, chronic N03.9

Richard Bright was the first to describe chronic glomerulonephritis in 1831 (Singer 1999).

In 2002, M R Pollak summarized a group of congenital diseases with primary podocyte damage and nephrotic syndrome under the term "true podocytopathies". These include, for example, minimal change disease, focal segmental glomerulosclerosis, and membranous nephropathy (Chebotareva 2018).

Chronic glomerulonephritis (CGN) refers to a chronic course of various glomerulopathies (Lohr 2002).

Various grading systems exist to assess the chronicity of glomerulonephritis (Sethi 2019):

- Standardized grading of chronic changes in the kidney (Sethi 201).

- Global and segmental glomerulosclerosis (GS) are graded from 0 to 3

- Tubule shrinkage with thickening of tubular basement membrane and flattening of tubular epithelium (TA) scored 0 to 3

- Interstitial fibrosis (IF) with 0 to 3

- Arteriosclerosis with 0 to 1

Scores are summed (total renal chronicity score) to classify the overall severity of chronic lesions into minimal (0 - 1 total score), mild (2 - 4 total score), moderate (5 - 7 total score), and severe (≥ 8 total score)

(Sethi 2017)

- Oxford classification of IgA nephropathy (Sethi 2019):

Here, four variables are required for predicting renal outcome:

(1) the mesangial hypercellularity score

(2) segmental glomerulosclerosis

(3) endocapillary hypercellularity

(4) tubular atrophy/interstitial fibrosis (Roberts 2009).

- Modified International Society of Nephrology / Renal Pathology Society classification of lupus nephritis (Sethi 2019):

This classifies glomerular lesions into classes I - IV (Bajema 2018).

- Berden- Classification for ANCA associated glomerulonephritis (Sethi 2019):

This classification system divides biopsies into 4 different categories (Berden 2010).

The acute form of glomerulonephritis (GN) usually heals. Only about 1 % of affected children and about 10 % of affected adults develop a chronic course (O'Brien 2021).

In most cases, CGN is caused by the same pathogens that can cause acute GN (O'Brien 2021):

- infectious glomerulonephritis

- genetic abnormalities

- autoimmune diseases

- however, in the vast majority of affected individuals, the cause remains unknown (O'Brien 2021).

In CGN, inflammation develops in the tubules. Due to the limited regenerative capacity of the glomerular structures, the inflammation progresses. Damage to the postmitotic podocytes (Weltsch 2018) results in impaired barrier function of the glomerular filter, leading to proteinuria and erythrocyturia. The severity of proteinuria represents a clinical equivalent for the activity or progression of CGN. (Chebotareva 2018).

The onset of the disease is usually gradual. Symptoms are only subtly expressed (O'Brien 2021).

There may be:

- erythrocyturia

- proteinuria

- arterial hypertension

- possibly nephrotic syndrome

In advanced stages, symptoms of renal insufficiency may occur, such as

- reduced physical performance

- edema

- dyspnea (Herold 2022)

- itching

- nausea

- Vomiting (O'Brien 2021).

In addition to anamnesis and clinical examination, laboratory parameters and abdominal sonography are of particular importance in the diagnosis. A biopsy is not (or no longer) indicated in most cases due to the lack of therapeutic consequences (Herold 2022).

Abdominal sonography

In CGN, the kidneys may appear inconspicuous on sonography for a prolonged period of time. Only as the disease progresses does a typically symmetrical organ shrinkage and narrowing of the parenchymal rim occur. Initially, the echo-poor medullary pyramids are still easily recognizable, but then there is an increasing homogeneous compression of the parenchymal rim pattern. In an advanced stage, changes of the surface, a coarsening of the parenchymal rim and poor differentiability of the renal sinus can be recognized (Seitz 2008).

- Proteinuria

- erythrocyturia

- If necessary, determination of specific antibodies (O'Brien 2021)

- Increase in creatinine(Seitz 2008)

In chronic diseases of the kidney, pathological changes are found both in the renal cortex, where they may affect glomeruli, tubules, interstitium, arteries and arterioles,

as well as in the renal medulla (Sethi 2017).

Segmental or global glomerulosclerosis is found in the glomeruli, and tubular atrophy and interstitial fibrosis in the interstitium (Sethi 2019).

The treatment of chronic glomerulonephritis is only possible symptomatically, whereby the control of arterial hypertension is of particular importance (Herold 2022).

Recommended drug therapy includes an ACE inhibitor or an angiotensin II receptor blocker (ARB), plus a low-salt diet. This often slows the progression of CGN, improves blood pressure, and reduces urinary protein excretion (O'Brien 2021).

Cure of chronic glomerulonephritis is not possible. The disease progresses towards terminal renal failure (Herold 2022). The prognosis itself depends on the histologically confirmed underlying disease (Bichler 2004).

It is estimated that terminal renal failure develops in 25-50% of affected individuals (Halfon 2017).

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