Nephritic syndrome

Not to be confused with nephrotic syndrome

Nephritic syndrome is a collection of signs (known as a syndrome) associated with disorders affecting the kidneys, more specifically glomerular disorders.

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Signs and symptoms

Nephritic syndrome is characterized by;

• proteinuria (protein in the urine)
• hematuria (blood in the urine), with red blood cell casts present in the urine
• hypertension (high blood pressure)

and variable renal insufficiency, with;

• azotemia (elevated blood nitrogen)
• oliguria (low urine output <400 mL/day)

The main features are hypertension and RBC casts. The proteinuria in nephritic syndrome is not usually severe, but may occasionally be heavy enough to be in the range usually found in nephrotic syndrome.

Mnemonic: PHAROH = Proteinuria, Hematuria, Azotemia, RBC casts, Oliguria, Hypertension

Diagnosis

Nephritic syndrome is not a specific diagnosis. It is a clinical syndrome and characterized by the above signs.

An anti-streptolysin O titre (or ASOT) is typically done to test for exposure to streptococci.

Pathophysiology

The exact pathophysiology is dependent on the specific diagnosis. However, the common features are an inflammation of the glomeruli, leading to salt and water retention and a reduction in the kidney function.

Differential diagnosis

The two classic diagnoses of nephritic syndrome are:

• post-infectious glomerulonephritis - also sometimes called post-streptococcal glomerulonephritis as the streptococcus is the most common cause and at one time was thought to be the only cause.
• crescentic glomerulonephritis

Nephritic syndrome causes are usually grouped into 'focal proliferative' and 'diffuse proliferative' on the basis of histology (obtained by a renal biopsy).

Focal proliferative

• IgA nephropathy
• chronic liver failure
• Celiac sprue
• dermatitis herpetiformis
• Henoch-Schoenlein purpura
• Alport syndrome
• SLE

Diffuse proliferative

• focal glomerulosclerosis
• membranoproliferative glomerulonephritis (malaria, hepatitis B, hepatitis C, chronic infection, sickle-cell disease, SLE, hemolytic uremic syndrome/thrombotic thrombocytopenic purpura)
• cryoglobulinemia
• SLE
• rapidly progressing glomerulonephritis (RPGNs) - several.

Treatment

Treatment is dependent on the underlying etiology (cause) and the degree of kidney dysfunction.

Prognosis

Prognosis depends on the underlying etiology.