erythrocyte cast (RBC cast)

Introduction

See urinary cast

Etiology

• glomerular bleeding
  • pathognomonic for glomerulonephritis

Clinical manifestations

• may be asymptomatic microscopic hematuria

Laboratory

• urine microscopy
  • erythrocytes may be distinct or incorporated into a homogeneous mass.
    • may occur as a cylindrical mass (~ 6 RBC wide, 16 RBC long)
  • orange-red appearance characteristic
    • may look brown rather than orange-red (MKSAP20 presented image)

Differential diagnosis

• muddy brown cast of acute tubular necrosis

More general terms

• urinary cast