Chronic kidney disease is an “invisible” killer that seriously affects the lives of kidney patients. Although early or mild declines in kidney function are often unnoticeable to kidney patients, they can significantly predict the progression of the disease (to the uremic stage) and the associated prognosis. A recent study from Hopkins University showed that the risk of progression to uremia in patients with a 30% decline in kidney function over 2 years was more than 5-fold higher in the moderately severely impaired group and more than 6-fold higher in the mildly impaired group. Similarly, the prognostic risk was predicted to be about 2-fold higher. Obviously, the faster the decline, the faster the progression of the disease, but considering the fact that the population of kidney patients with mild renal function decline is more extensive, mild renal function decline is more valuable and meaningful for the prediction of the condition of the majority of kidney patients. After all this, how to assess kidney function? The simplest way is to take blood for kidney function test, but because of the volatility of blood creatinine and many influencing factors, it is better to have the relevant formula converted to standard glomerular filtration rate by professionals to help clarify. In addition to this, a more accurate assessment of glomerular filtration rate can be done by applying nuclear tracing. Knowing how to assess is only the beginning, performing continuous periodic checkups for assessment and documentation is the means that can ultimately lead to monitoring changes in kidney function. Usually, a general outpatient visit is only for a single visit, which does not allow for continuous documentation and assessment of the prognosis of the condition.