Reduced kidney volume indicates that there is chronic kidney disease, which is some kind of cause destroying and damaging the kidney, leading to destruction of kidney tissues, and ultimately resulting in reduced kidney volume. Generally speaking, the causes that can cause kidney volume reduction exist chronically for a long time, and the common causes include primary chronic glomerulonephritis, diabetes mellitus, hypertension, systemic lupus erythematosus, kidney stones, renal tuberculosis, chronic pyelonephritis, or congenital dysplasia, and so on. No matter what the cause is, the persistence of these factors will eventually cause glomerulosclerosis and tubular fibrosis, which will result in the loss of renal function, which is manifested as a reduction in kidney size on ultrasound or CT.