Kidney failure

Kidney failure is a serious medical condition where the kidneys can no longer filter waste products from the blood effectively. This occurs when the organs function at less than 15% of their normal capacity. This state is sometimes called end-stage renal disease (ESRD). Because the kidneys are responsible for cleaning the blood and maintaining balance, failure affects many parts of the body. It can be classified into two main types: acute and chronic. Acute failure develops rapidly and may be reversible. Chronic failure develops slowly and is often irreversible.

Acute kidney injury (AKI) happens when the blood supply to the kidneys is suddenly interrupted. It can also occur when the kidneys are overloaded with toxins. One cause is a sudden loss of blood flow during surgeries, such as heart-bypass surgery. Other causes include drug overdoses or even bee stings. In some cases, a condition called crush syndrome causes AKI. This happens when toxins from damaged muscles are suddenly released into the blood. This release includes substances like myoglobin, potassium, and phosphorus. These products can clog and destroy the kidneys during a process called reperfusion injury.

Chronic kidney disease (CKD) is a slower process that can lead to permanent damage. The most common causes are diabetes mellitus and long-term, uncontrolled hypertension, which is high blood pressure. Other causes include polycystic kidney disease, where large fluid-filled cysts grow on the kidneys. Some people may also develop CKD from long-term lithium treatment. For example, about 0.53% of people on lithium develop end-stage renal failure. Genetic factors also play a role. The APOL1 gene is a major risk factor for certain types of kidney failure in people of African origin.

When the kidneys fail, waste products build up in the blood. This condition is called azotemia. If the buildup is severe enough to cause noticeable symptoms, it is called uremia. Symptoms can vary widely between different people. Some may experience vomiting, nausea, or a loss of appetite. Others might notice swelling in their hands, legs, or face. High levels of potassium in the blood, known as hyperkalemia, can cause abnormal heart rhythms or muscle paralysis. A buildup of phosphates can lead to itching or even bone damage.

Kidney failure also affects the blood through a condition called anemia. Healthy kidneys produce a hormone called erythropoietin. This hormone tells the bone marrow to make red blood cells. When kidneys fail, they produce less erythropoietin. This results in fewer red blood cells to carry oxygen. People with anemia often feel very tired, weak, or dizzy. They may also have trouble concentrating or experience low blood pressure. Additionally, damaged kidneys may allow large proteins to leak into the urine, causing it to look foamy or bubbly.

Doctors diagnose kidney failure by measuring the glomerular filtration rate (GFR). The GFR measures how well the kidneys filter blood. Chronic kidney disease is divided into five distinct stages based on this rate. Stage 1 shows mildly diminished function with few symptoms. Stages 2 and 3 require increasing medical support to slow the decline. Stages 4 and 5 are the most severe. Stage 5 is equivalent to end-stage renal disease, where the GFR is less than 15 ml/min. Doctors also look at serum creatinine levels to track kidney health.

Treatment depends on whether the failure is acute or chronic. For acute failure, doctors treat the underlying cause to help the kidneys recover. For chronic failure, patients often need renal replacement therapy. One method is hemodialysis, which uses a machine to filter blood outside the body. Another method is peritoneal dialysis. This involves placing a specific fluid into the abdominal cavity to clean the blood. Some patients may undergo a kidney transplant. This surgery places a kidney from another person into the patient's body. Patients receiving a transplant must take immunosuppressant medication to prevent rejection.

Kidney failure affects many people globally. In the United States, acute failure affects about 3 per 1,000 people every year. Chronic failure affects about 1 in 1,000 people. In Canada, the lifetime risk of end-stage renal disease is estimated at 2.66% for men and 1.76% for women. While the condition is serious, many people with chronic disease can continue working with appropriate treatment. Managing the condition often includes staying active and making specific dietary changes. It is also important to monitor mental health, as depression is common among these patients.