An Overview of Kidney Disease
Kidney disease refers to injury to the kidneys caused by various factors. It leads to changes in the physiological structure of the kidneys and impairment of renal function. Generally, kidney diseases can be classified by the cause of injury into primary and secondary kidney diseases, and by the course of injury into acute kidney injury (AKI) and chronic kidney disease (CKD). Acute kidney injury refers to a sharp decline in renal function within 7 days or less; chronic kidney disease refers to structural or functional abnormalities of the kidneys lasting more than 90 days. Some patients with acute kidney injury who do not improve after treatment progress to chronic kidney disease.
The kidneys are the body's core metabolic organs. Metabolic waste and toxins such as urea nitrogen, creatinine, and uric acid must pass through glomerular filtration and tubular secretion, and are then excreted from the body in the form of urine. The kidneys also adjust urine volume according to the body's needs, controlling water intake and output to prevent dehydration or edema, so people with impaired renal function may develop water metabolism disorders.
The body's electrolyte and acid-base balance also requires renal regulation. Renin can also activate the renin-angiotensin system, dilating blood vessels to lower blood pressure and maintain the dynamic balance of blood pressure. The erythropoietin (EPO) secreted by the kidneys stimulates bone marrow hematopoiesis; insufficient EPO secretion leads to renal anemia. The toxic portions of the drugs and foods we ingest also depend on the kidneys for metabolism.
So renal insufficiency causes a series of problems and adversely affects health. Whether renal function is intact can be determined through blood tests and urine tests. Mild kidney disease has no obvious symptoms, but progressive kidney disease causes difficulties in the body's water metabolism, excessive urine protein in the urine, and elevated blood creatinine, urea nitrogen, and uric acid. Nephritis patients also show elevated infection-related indicators, and severe cases lead to renal failure.
China has a large number of kidney disease patients. The overall prevalence of chronic kidney disease among Chinese adults is 10.8%, meaning about 120 million Chinese adults have chronic kidney disease. In 2017, an epidemiological survey of chronic kidney disease among 6,795 community residents aged 60 and above in Jiading District, Shanghai, found that 9.7% of the subjects had proteinuria, 6.1% of the elderly had hematuria, and 6.9% had reduced renal function.
Chronic kidney disease is associated with hypertension, diabetes, smoking, obstructive uropathy, hyperuricemia, and hyperhomocysteinemia. Moreover, chronic kidney disease has a certain familial hereditary component; the prevalence of chronic kidney disease among first-degree relatives of Chinese CKD patients is 29.7%, which is related to both genes and lifestyle.
Generally, patients admitted to hospital in various departments basically all have their liver and kidney function checked. People with renal insufficiency cannot undergo many examinations and treatments normally. Because renal function is insufficient and normal metabolism is impossible, some harmful agents that cannot be excreted in time can easily cause medical accidents. For example, if contrast agents (such as iodine or barium sulfate) cannot be metabolized normally and remain in the body too long, they may cause new diseases in the patient. Therefore, people with renal insufficiency should not undergo contrast-enhanced CT examinations requiring contrast agents in hospitals. Many drugs are also nephrotoxic (such as certain antibiotics or anti-tumor drugs), and taking them is dangerous for renal insufficiency patients; even healthy people may develop abnormal renal function after long-term use. Many Chinese herbs are nephrotoxic and require caution in use; kidney damage caused by the abuse of herbal tonics has been frequently reported, which is related to the public's lack of knowledge about kidney disease.
In clinical practice, many patients with renal insufficiency have been caused by medication; these are secondary kidney disease patients. For example, using antibiotics for too long or intolerance to chemotherapy or targeted drugs can all cause kidney damage. Once the kidneys are damaged, corresponding measures must be taken to restore renal function, and treatments harmful to the kidneys should be stopped when necessary. If renal function cannot be restored for a long time, many subsequent troubles will arise. So for people on long-term medication, regular re-examination of liver and kidney function is very necessary.