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Kidney diseases and kidney failure About kidneys The kidneys are a pair of bean-shaped organs located at the back of the body at about the level of the waist. Each kidney measures 10-15 cm in length and weighs approximately 160 grams. The kidney is made up of approximately one million functioning units called nephrons. Each nephron consists of the glomerulus and tubule. The tubule is a tube-like structure. The closed end of the tubule forms a cup-shaped structure called a glomerular capsule which surrouns a network of tiny blood vessels called the glomerulus. The glomerulus serves as a filter. The filtrate then drains into the tubule. The concentration of the filtrate is altered along the length of the tubule by various processes to form urine. The remaining nephron leads into the collecting duct. The collecting ducts drain into a common funnel-shaped sac called the kidney pelvis located on the hollow side of the kidney. The ureter connects the kidney pelvis with the bladder. Urine formed by the kidneys flow through the ureters to the bladder where it is passed out through the urethra.
Functions of the kidney The vital functions of the kidney are to remove toxic and waste products and excess water from the body. Other functions are to maintain the body’s balance of various salts, such as sodium, potassium, calcium, phosphates as well as acid. The kidney is also a producer of hormones. Erythropoietin is responsible for stimulating production of red blood cells in the bone marrow, while active Vitamin D is necessary for strong and healthy bones. Kidney diseases There are many kidney diseases, such as glomerulonephritis, pylonephritis, polycystic kidney and lupus nephritis. The treatment and potential for recovery depends on the type of disease. If the excretory function of the kidneys decreases below 5-10%, the phase of “End-Stage Renal Disease” (ESRD) has been reached. Renal replacement therapy is necessary to survive from this condition.
Kidney failure Kidney (renal) failure is a condition in which the kidneys are incapable of performing their normal functions. Certain toxic substances, which should have been excreted, such as urea and creatinine, accumulate in the body. These levels, if high, may cause symtoms such as tiredness, weakness, loss of appetite and vomiting. Besides, in kidney failure the volume of water in the body increases, resulting in swelling of tissue. Excess salt and water retention may cause high blood pressure, swelling of the legs, face, abdomen and breathlessness. Acid, generated during the body’s metabolic processes, builds up and causes metabolic acidosis. The kidneys fail to excrete phosphate, causing the blood phosphate to increase and calcium level to fall. When calcium level is low, bones will become brittle. The kidney looses its ability to produce erythropoietin, resulting in anemia. Creatinine is the breakdown product of muscle. The blood creatinine is often used as a measure of the degree of kidney failure. Generally, when the creatinine level in the blood reaches a level of 900 mol/l, the patient should start on dialysis. Causes of kidney failure The most common causes of kidney failure are glomerulonephritis (inflammation of the kidney) and diabetes mellitus. Other causes are kidney stones, polycystic kidneys, systemic lupus erythematosus (SLE), uncontrolled hypertension and drugs.
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