Nephritic syndrome

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

Signs and symptoms

Nephritic syndrome is characterized by proteinuria (protein in the urine), hematuria (blood in the urine), azotemia (elevated blood nitrogen), red blood cell (RBC) casts, oliguria (low urine output <400 mL/day) and hypertension (high blood pressure). The main features are hypertension and RBC casts. The proteinuria in nephritic syndrome is not severe, if it is severe the patient likely has a mix of nephritic syndrome and 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).