The kidneys are solid organs located on either side of the retroperitoneal spine in the lumbar region, one on each side, with a shape like a broad bean, with a bulging outer edge and a concave inner edge in the middle. About the size of two fists, each kidney is about 9-12 cm long, 5-6 cm wide, 3-4 cm thick, and 120-150 g in weight. Both kidneys are roughly similar in shape, size and weight, with the left kidney being slightly larger than the right kidney. The main structures of the kidney include: (1) glomerulus: completes the filtration function of the kidney, removes metabolites and toxic substances from the body; (2) renal tubules: reabsorbs useful substances (sugar, amino acids, small molecules of protein and minerals, etc.) filtered out by the glomerulus, locally secretes certain regulatory factors, excretes certain metabolites and drugs for their removal, and regulates the acid-base and water balance of the body; (3) collecting duct and renal pelvis: urine (3) the collecting ducts and renal pelvis: urine discharge lines, involved in the regulation of the body’s water balance. The kidneys excrete metabolic wastes, excess water and electrolytes such as potassium, sodium, chloride and hydrogen ions through the production of urine, which plays the role of excreting metabolic wastes and toxins, regulating water, electrolyte and acid-base balance, and maintaining the stability of the body’s internal environment; the kidneys filter and clean about 200 liters of blood per day – a quantity equivalent to 1 0 buckets of of drinking water! The kidneys also have important endocrine functions, producing vasoactive substances such as renin, prostaglandins, kinins and bradykinin, which regulate blood pressure to keep it relatively stable; they produce erythropoietin and active vitamin D3 to promote bone marrow hematopoiesis and regulate calcium and phosphorus metabolism. If the kidney is damaged, metabolic wastes and toxic substances cannot be excreted from the body and are retained in the body, uremia will occur, damaging various organs and systems in the body and endangering life; when the kidney is diseased, the filtration function of the kidney is impaired and cannot excrete excess water, toxic substances and electrolytes from the body, which easily leads to water and sodium retention and disturbance of electrolyte and acid-base balance, resulting in a series of clinical symptoms, such as swelling, low urine In serious cases, if not rescued in time, it may lead to death; renal lesions lead to a decrease in erythropoietin, which cannot effectively stimulate bone marrow hematopoiesis, resulting in anemia, which is called “renal anemia” by doctors. This is the main cause of severe anemia, and recombinant human erythropoietin is injected to correct the anemia; if the kidneys cannot produce active vitamin D3, the intestinal tract will absorb less calcium from the ingested food, lower blood calcium, higher blood phosphorus, secondary hyperparathyroidism, leading to osteoporosis, bone softening and ectopic calcification, bone pain, fractures, and generalized skin itching and neuropathy.