In glomerulonephritis, the red blood cells extrude through the diseased glomerular basement membrane and enter the renal tubules. When passing through the various segments of the renal tubules and subject to different osmotic pressure and PH, the red blood cells become deformed, from the normal double-sided central depression and disc shape to a variety of deformed red blood cells, such as ring-shaped (fried doughnut-like), bud-shaped, spiny, etc. The red blood cells become smaller in size or even rupture. This is often accompanied by edema, hypertension, proteinuria, and an increased urinary albumin/total protein ratio. It is important to note that urinary red blood cell abnormalities are not always of glomerular origin.