In medical clinical practice, the diagnosis and treatment of diseases are not only “accurate” (clear diagnosis), but also “early” (early detection). In terms of chronic kidney disease, the earlier the diagnosis, the earlier the treatment can delay the rhythm of most kidney disease patients into uremia. Although the histopathological examination of kidney biopsy, quantitative changes in blood creatinine and urine protein, which are widely used in clinical practice, can accurately reflect the changes in kidney function, they lack sensitivity. Because the ultimate goal of kidney disease treatment is to reduce the duration of kidney damage and delay the progressive decline of kidney function, the above-mentioned examinations all revolve around the nature and extent of kidney tissue destruction and the status of residual kidney function, etc. When these indicators show abnormalities, a significant proportion of patients often have progressed to a certain stage, especially those who have combined obvious clinical symptoms (swelling, anemia, severe This is especially true for patients with kidney disease who have a combination of significant clinical symptoms (edema, anemia, severe hypertension, etc). Therefore, finding more sensitive and accurate monitoring indicators for kidney disease is a hot spot for nephrologists to focus on. One of the core aspects in the development of kidney disease is that the intra-glomerular pressure (glomerular perfusion pressure) and the integrity of the glomerular membrane are damaged, and finding indicators that can determine these changes is the early detection of kidney disease. Albumin is one of the most important plasma proteins. Under normal circumstances, the molecular weight of albumin is too large to cross the glomerular basement membrane, therefore, only a very low concentration of albumin is present in the urine of healthy people, specifically not more than 20 mg per liter, so it is also called “urine microalbumin test”. In the early stages of some diseases, such as diabetic nephropathy stage 1-2, hypertensive kidney damage and the early stages of some obesity-related kidney damage, it is common to combine the phenomenon of increased intra-glomerular pressure, and most patients can find a large amount of microalbumin in their urine before they have any clinical disease. In the early stages of chronic kidney disease, a significant number of patients can reverse the progression of the disease with timely intervention. In the early stages of chronic kidney disease, when functional changes in the permeability of the glomerular membrane (changes in the negative charge of the membrane) occur, small molecules of albumin can leak through the membrane into the urine, and regular checkups can help detect kidney disease as early as possible. For some patients with clearly diagnosed kidney disease, although urinary albumin can leak into the urine along with other large molecules of protein, this test has lost its sensitivity, but its dynamic changes can help determine the effectiveness of its treatment and prevention. For some patients whose kidney disease is in remission, regular examination of microalbumin urine can also help to warn the recurrence of the disease. Therefore, microalbumin is a very important, practical and sensitive indicator that should be promoted and tested regularly, rather than wait until you are clinically unwell and then perform this test long before it loses its significance. The most ideal way to measure urine albumin is to take a 24-hour urine specimen. Since there is a large degree of variability in urine albumin excretion, an increase in albumin excretion in an untimed urine specimen (random urine) may not be meaningful, but 2 to 3 consecutive increases are of diagnostic value. Measurement methods include radioimmunoassay, enzyme-linked immunosorbent assay (ELASA), etc. For this reason, I asked my assistant Xiao Liu to write an article about the clinical significance of this test.