The nephritic syndrome is the name given to a cluster of symptoms and signs. It can be caused by a number underlying pathologies affecting the kidneys, but in itself is not a diagnosis. These diseases lead to inflammation in the glomeruli (glomerulonephritis), the kidneys filtering units. Patients tend to present acutely, and can be very unwell requiring rapid intervention.
It is a separate entity from nephrotic syndrome, in which dysfunction of the basement leads to the leakage of protein into the urine resulting in proteinuria, hypoalbuminaemia, and oedema.
Damage to the glomerulus occurs by an immune-mediated injury. This inflammatory reaction is started either by an antibody targeted at a component of the glomerulus, such as in anti-GBM disease when the target is the basement membrane. Or because immune complexes generated elsewhere in the body are trapped by glomerular filtration, as occurs in post-streptococcal glomerulonephritis (PSGN). These antibodies/immune complexes in turn lead to the activation of the complement cascade and infiltration of inflammatory cells. The exact mechanism of injury depends on the underlying disease process but the following histologic features are common:
These changes can affect some (segmental) or all (global) of the glomerulus, and can affect some (focal) or all (diffuse) of the glomeruli within the kidneys.
As a result the filtration capabilities of the glomerulus are affected. The glomerular basement membrane is damaged and it thus allows protein and red blood cells to leak through. As these transit through the nephron casts can be formed. Light microscopy of the patients urine may be used to detect these, and they are pathognomic of glomerular disease. Glomerular filtration rate is reduced stimulating the retention of salt and water culminating in hypertension and oedema. As there is decreased filtering of the blood, levels of waste products rise resulting in azotemia, and the production of urine falls (oliguria).
In this disease, not all glomeruli are affected (focal), and of those that are affected not all of the glomerulus is involved (segmental). There has been a proliferation of cells within Bowman's space taking the form of a crescent, this is the reason for the alternative name of crescenteric glomerulonephritis.
(adapted from J.Charles Jennette, www.unckidneycenter.org)
As stated a number of diseases can cause the nephritic syndrome:
Post-Streptococcal Glomerulonephritis (PSGN):
Non-Streptococcal post-infectious GN:
Rapidly Progressive Glomerulonephritis (RPGN):
In itself caused by different underlying pathologies;
Haemolytic Uraemic Syndrome:
For more information of the various glomerulonephritidies, please consult the article on glomerulonephritis.
The goal of treatment is two-fold.
Treatment targeted at addressing glomerular inflammation will vary depending on the underlying disease etiology, and is not within the scope of this article.
Acute phase management will depend on the patient's parameters, but is likely to include:
Once the patient is stable, it is reasonable to undertake investigations in order to identify the underlying cause and manage it appropriately. This is likely to include:
This is related to the underlying pathology of the nephritic syndrome, and varies widely. As stated, nephritc syndrome is not a diagnosis.
Kumar, P. & Clark, M. Clinical medicine. 8th ed; Edinburgh: Elsevier Saunders.
Fastbleep © 2019.