Common Causes of Abnormality in Kidney Size

Under normal circumstances the kidneys are not easy to be touched by us; therefore the significance of kidney size is often neglected. If more than 1/2 of the renal lower parts can be touched, it is nephroptosis in clinic. B ultrasound shows that the general normal size of kidney is 10-12cm in length, 5-7cm in width and 3-5cm in thickness and those that are beyond the range are enlarged kidneys. Abnormalities in kidney size include:
Kidney enlargement:
1. Polycystic Kidney Disease (PKD). Usually patients have illness history and some patients can have the complication of polycystic liver. B ultrasound can find multiple cystic masses in the kidneys.
2. Renal tumors. Malignant renal tumors can cause obvious enlargement of the kidneys. Benign tumors are usually small and can cause hematuria, pains in renal area. B ultrasound or CT scan can find cystic masses whose density is inconsistent with the renal parenchyma.
3. Large retention of fluids in the kidneys. Such as hydronephrosis, pyonephrosis. The diagnosis is not difficult depending on the patients’ clinical manifestations and imaging tests.
4. Acute renal failure. In the early stage of acute renal failure, the kidneys can be enlarged and other symptoms include anuria, oliguria, and hypertension, increase of serum creatinine and urea nitrogen.
5. Acute glomerulonephritis. The kidneys can be slightly enlarged and diagnosis can be confirmed according to the incubation period of upper respiratory tract infections and related checks.
Kidney shrinkage:
1. Chronic renal failure. Usually the shrinkage is bilateral kidneys and the diagnosis can be made according to illness history of chronic kidney diseases, anemia and renal function examination.
2. Congenital renal dysplasia. In most cases only one kidney shrinks and the other one can be normal or enlarged. In clinic patients can only have abnormal urine test or hypertension.
3. Renal tuberculosis. Usually the diseased kidney is shrunk and the other one suffers from severe hydronephrosis or compensatory enlargement. Clinical manifestations include hematuria or puuria. The Mycobacterium in the urine is the most reliable basis for the diagnosis of renal tuberculosis.
4. Renal artery stenosis. The diseased kidney is shrunk obviously and it is often accompanied by severe hypertension and vascular murmur in the abdomen can be heard and selective angiography can confirm the diagnosis.
5. Chronic pyelonephritis. It can be bilateral shrinkage or only the diseased kidney is shrunk. Patients usually have recurrent urinary tract infections, pyuria or bacteriuria. Intravenous pyelogam shows deformation of the renal pelvis and renal lamp and the appearance is not smooth. B ultrasound shows that the surface of the kidneys is uneven.
6. Renal cystic medulla syndrome. Usually patients have family history of the disease and the cysts are usually small and not easy to be detected. Bilateral kidneys are shrunk and wrinkled. Clinical manifestations include polyuria, thirst, loss of salt in urine and interstitial nephritis. In case of unexplained renal failure in children and young people, this disease should be considered.