Overview

Nephritic syndrome is an inflammatory process that is defined as the presence of one or more of the following:

• Hematuria with acanthocytes

• RBC casts in urine

• Proteinuria (< 3.5 g/24 h)

• Hypertension

• Mild to moderate edema

• Sterile pyuria

• Oliguria

• Azotemia

NephrItic syndrome indicates glomerular Inflammation.

• General pathophysiology

  • Inflammation → cytokine release → glomerular capillary damage

    • Porous glomerular basement membrane → leakage of proteins and RBCs → nephritic sediment (all blood components are detectable on urinalysis)

      • Proteinuria (< 3.5 g/24h): leakage of proteins

      • Hematuria: leakage of RBCs, which stick together and form red blood cell casts in the renal tubules

    • Oliguria: inflammatory infiltrates reduce fluid movement across the membrane (↓ GFR)

    • Azotemia: inflammation prevents sufficient filtering and excretion of urea

    • Salt retention → intravascular volume expansion → hypertension and edema

• Membranoproliferative glomerulonephritis: characterized by deposition of antibodies between podocytes and the basal membrane

  • Type 1: subendothelial immune complex deposits

  • Type 2 (dense deposit disease): intramembranous deposition of complement C3 (C3 nephritic factor, an IgG autoantibody that stabilizes C3 convertase, continuously activates C3, leading to its depletion)

• Intermittent gross hematuria (red or brown urine, i.e., cola-colored urine)

• Hypertension

• Pitting edema

• In ↓ GFR: oliguria and uremic symptoms (see “Uremia”)

• For a comparison of nephrotic and nephritic syndrome see “Nephrotic vs. nephritic syndrome”