What does "nephritis" mean and what are its types?

Nephritis means inflammation of the kidney, from nephr meaning kidney and itis meaning inflammation. Glomerulonephritis specifically affects the glomeruli, the tiny filtering units within the kidneys, and can be acute or chronic. Pyelonephritis is infection and inflammation of the renal pelvis and kidney tissue, usually from a urinary tract infection that ascends from the bladder. Interstitial nephritis involves inflammation of the spaces between the renal tubules, often caused by medications or autoimmune conditions.