In case of chronic kidney disease both of the kidneys are generally small in size. If there is an old USG report, it will help your doctor to compare the change of kidney sizes.
Kidney size detection by USG helps to differentiate chronic versus acute renal failure. It’s important to differentiate between these two type of kidney failures since the acute type of renal failure is may be reversible if prompt treatment can be given at time, whereas the chronic renal failure is an irreversible procedure.
However, there is an exception to the rule, not always kidney sizes will be reduced in chronic kidney disease.. Certain conditions like in diabetes (diabetic nephropathy), amyloidosis, HIV (HIV nephropathy) and polycystic kidney disease – the kidney sizes might not be small, instead normal or enlarged in size.
In certain scenarios, a chronic kidney disease patient can develop acute renal failure due to some cause (e.g. loose motion leading to loss of hypovolamia). In this type of clinical situations where acute on chronic kidney failure occues clinical correlation along with other investigation reports are required to make the diagnosis.
Although, USG examination of the kidneys is a vital examination in the process of diagnosis chronic kidney disease, USG examination is not the sole test for the diagnosis of chronic kidney disease, it’s done in addition to tests like serum urea and creatinine level, urine electrolytes, glomerular fitation rate estimation, renal biopsy etc.