Chronic kidney disease

[Dorothey Allen]

Chronic kidney disease is a slowly progressive (months to years) decline in the kidneys’ ability to filter metabolic waste products from the blood.

Major causes are diabetes and high blood pressure.
Blood becomes more acidic, anemia develops, nerves are damaged, bone tissue deteriorates, and risk of atherosclerosis increases.
Symptoms can include urinating at night, fatigue, nausea, itching, muscle twitching and cramps, loss of appetite, confusion, difficulty breathing, and body swelling (most commonly the legs).
Diagnosis is by blood and urine tests.
Treatment aims to restrict fluids, sodium, and potassium in the diet, use drugs to correct other conditions (such as diabetes, high blood pressure, anemia, and electrolyte imbalances), and, when necessary, use dialysis or kidney transplantation.

(See also Overview of Kidney Failure.)
Many diseases can irreversibly damage or injure the kidneys. Acute kidney injury becomes chronic kidney disease if kidney function does not recover after treatment and lasts more than three months. Therefore, anything that can cause acute kidney injury can cause chronic kidney disease. However, in Western countries, the most common causes of chronic kidney disease are

Diabetes mellitus
High blood pressure (hypertension)

Both of these conditions directly damage the kidneys’ small blood vessels.
Other causes of chronic kidney disease include urinary tract blockage (obstruction), certain kidney abnormalities (such as polycystic kidney disease and glomerulonephritis), and autoimmune disorders (such as systemic lupus erythematosus [lupus]) in which antibodies damage the tiny blood vessels (glomeruli) and the tiny tubes (tubules) of the kidneys.
Chronic kidney disease causes many problems throughout the body:

When loss of kidney function is mild or moderately severe, the kidneys cannot absorb water from the urine to reduce the volume of urine and concentrate it.
Later, the kidneys have less ability to excrete the acids normally produced by the body and the blood becomes more acidic, a condition called acidosis.
Production of red blood cells decreases, leading to anemia.
High levels of metabolic waste products in the blood can damage nerve cells in the brain, trunk, arms, and legs. Uric acid levels may increase, sometimes causing gout.
Diseased kidneys produce hormones that increase blood pressure. In addition, diseased kidneys cannot excrete excess salt and water. Salt and water retention can contribute to high blood pressure and heart failure.
The sac that surrounds the heart (pericardium) may become inflamed (pericarditis).
The level of triglycerides in the blood is often elevated, which, along with high blood pressure, increases the risk of atherosclerosis.
The formation and maintenance of bone tissue may be impaired (renal osteodystrophy) if certain conditions that accompany chronic kidney disease are present for a long time. These conditions include a high level of parathyroid hormone, a low concentration of calcitriol (the active form of vitamin D ) in the blood, impaired absorption of calcium, and a high concentration of phosphate in the blood. Renal osteodystrophy may lead to bone pain and an increased risk of fractures.