Why does a kidney get bigger?

Kidneys can enlarge due to a variety of factors. Some common causes include:

1. Hydronephrosis: This is a condition where urine gets backed up in the kidney, causing it to swell. Hydronephrosis can be caused by a blockage in the ureter, which is the tube that carries urine from the kidney to the bladder. This blockage can be caused by kidney stones, tumors, or other conditions.

2. Polycystic kidney disease: This is a genetic condition in which cysts develop in the kidneys. These cysts can grow large and cause the kidneys to enlarge.

3. Kidney infection (pyelonephritis): A bacterial infection of the kidney can cause swelling and inflammation, leading to an enlarged kidney.

4. Kidney tumors: Both benign and malignant tumors can cause the kidney to become enlarged.

5. Diabetic nephropathy: Chronic high blood sugar levels in diabetes can damage the kidneys and cause them to enlarge.

6. Glomerulonephritis: This is a group of conditions that cause inflammation of the glomeruli, which are the filtering units in the kidneys. Glomerulonephritis can lead to kidney enlargement.

7. Medullary sponge kidney: This is a rare condition in which the collecting ducts in the kidney become dilated and form cysts. The cysts can enlarge the kidney and cause pain and other symptoms.

8. Renal vein thrombosis: If the renal vein that drains blood from the kidney becomes blocked by a blood clot, the kidney can enlarge due to the buildup of pressure.

If you have an enlarged kidney, it's important to see a doctor to determine the cause and receive appropriate treatment.