Low albumin is a decrease in the concentration of albumin in the plasma, which may be caused by a variety of reasons, such as malnutrition and liver disease; when the body has low albumin, it may lead to the appearance of symptoms such as edema. Plasma albumin, also known as clear protein, is a more functional and abundant plasma protein. In general, the plasma albumin level in healthy adults ranges from 35 to 50 g/L. A significant decrease in albumin level may indicate the presence of related diseases. Albumin is important for maintaining plasma colloid osmotic pressure, transporting substances, scavenging free radicals, detoxifying, and providing energy. The causes of low plasma albumin may include malnutrition, such as chronic loss of appetite, prolonged diarrhea, malabsorption syndrome, etc. Liver diseases, such as hepatitis, acute hepatic necrosis, cirrhosis, etc., which can lead to impaired albumin synthesis. Kidney diseases, such as diabetic nephropathy, nephrotic syndrome, hypertensive nephropathy, etc., will lead to excessive loss of albumin; infections, inflammation, cancer, etc., will accelerate its catabolism. When the body’s albumin is low, normal physiological functions will be affected, usually with symptoms such as limb edema and ascites. It is recommended that the corresponding groups of people should consult the doctor in time and be treated actively after the cause of the disease has been clarified.