Chronic kidney disease

Chronic kidney disease (CKD) is long-term damage that reduces the kidneys' ability to filter the blood. Doctors define it as a lowered filtering rate, or signs of kidney damage such as protein in the urine, that last more than three months. Healthy kidneys clear wastes and extra water as urine, balance salts such as potassium and phosphate, help regulate blood pressure and produce hormones such as erythropoietin, which drives red blood cell production.

Diabetes and high blood pressure cause most cases by slowly injuring the glomeruli, the tiny filters inside each nephron. Glomerular inflammation, inherited polycystic kidney disease, blockages and some medicines are other causes. Because the surviving nephrons work harder to compensate, early CKD usually causes no symptoms, and most people who have it do not know. As function falls, patients may develop swollen ankles, tiredness, itching, poor appetite, anemia, weak bones and high potassium, and the disease sharply raises the risk of heart attack and stroke.

A blood test for creatinine is used to estimate the glomerular filtration rate (eGFR), and a urine test measures albumin; together they place the disease in one of five stages. Controlling blood pressure and blood sugar, with drugs such as ACE inhibitors and SGLT2 inhibitors, slows its progress. When the kidneys fail, survival depends on dialysis or a kidney transplant.