Your kidneys are two bean-shaped organs, each about the size of your fists. They are located near the middle of your back, just below the rib cage. Inside each kidney about a million tiny structures called nephrons filter blood. They remove waste products and extra water, which become urine. The urine flows through tubes called ureters to your bladder, which stores the urine until you go to the ba
throom. This damage may leave kidneys unable to remove wastes. Causes can include genetic problems, injuries, or medicines. You are at greater risk for kidney disease if you have diabetes, high blood pressure, or a close family member with kidney disease. Chronic kidney disease damages the nephrons slowly over several years. Other kidney problems include:
- Cancer
- Cysts
- Stones
- Infections
Your doctor can run tests to find out if you have kidney disease. If your kidneys fail completely, a kidney transplant or dialysis can replace the work your kidneys normally do. The kidneys are connected to the urinary bladder by tubes called ureters. Urine is stored in the urinary bladder until the bladder is emptied by urinating. The bladder is connected to the outside of the body by another tube like structure called the urethra. The main function of the kidneys is to remove waste products and excess water from the blood. The kidneys process about 200 liters of blood every day and produce about 2 liters of urine. The waste products are generated from normal metabolic processes including the breakdown of active tissues, ingested foods, and other substances. The kidneys allow consumption of a variety of foods, drugs, vitamins and supplements, additives, and excess fluids without worry that toxic by-products will build up to harmful levels. The kidney also plays a major role in regulating levels of various minerals such as calcium, sodium, and potassium in the blood. As the first step in filtration, blood is delivered into the glomeruli by microscopic leaky blood vessels called capillaries. Here, blood is filtered of waste products and fluid while red blood cells, proteins, and large molecules are retained in the capillaries. In addition to wastes, some useful substances are also filtered out. The filtrate collects in a sac called Bowman's capsule. The tubules are the next step in the filtration process. The tubules are lined with highly functional cells which process the filtrate, reabsorbing water and chemicals useful to the body while secreting some additional waste products into the tubule. The kidneys also produce certain hormones that have important functions in the body, including the following:
Active form of vitamin D (calcitriol or 1,25 dihydroxy-vitamin D), which regulates absorption of calcium and phosphorus from foods, promoting formation of strong bone. Erythropoietin (EPO), which stimulates the bone marrow to produce red blood cells. Renin, which regulates blood volume and blood pressure. Chronic kidney disease:
Chronic kidney disease occurs when one suffers from gradual and usually permanent loss of kidney function over time. This happens gradually, usually over months to years. Chronic kidney disease is divided into five stages of increasing severity (see Table 1 below). The term "renal" refers to the kidney, so another name for kidney failure is "renal failure." Mild kidney disease is often called renal insufficiency. With loss of kidney function, there is an accumulation of water, waste, and toxic substances in the body that are normally excreted by the kidney. Loss of kidney function also causes other problems such as anemia, high blood pressure, acidosis (excessive acidity of body fluids), disorders of cholesterol and fatty acids, and bone disease. Stage 5 chronic kidney disease is also referred to as kidney failure, end-stage kidney disease, or end-stage renal disease, wherein there is total or near-total loss of kidney function. There is dangerous accumulation of water, waste, and toxic substances, and most individuals in this stage of kidney disease need dialysis or transplantation to stay alive. Unlike chronic kidney disease, acute kidney failure develops rapidly, over days or weeks. Acute kidney failure usually develops in response to a disorder that directly affects the kidney, its blood supply, or urine flow from it. Acute kidney failure is often reversible, with complete recovery of kidney function. Some patients are left with residual damage and can have a progressive decline in kidney function in the future. Others may develop irreversible kidney failure after an acute injury and remain dialysis-dependent. Chronic Kidney Disease Causes:
Although chronic kidney disease sometimes results from primary diseases of the kidneys themselves, the major causes are diabetes and high blood pressure. Type 1 and type 2 diabetes mellitus cause a condition called diabetic nephropathy, which is the leading cause of kidney disease in the United States. High blood pressure (hypertension), if not controlled, can damage the kidneys over time. Glomerulonephritis is the inflammation and damage of the filtration system of the kidneys, which can cause kidney failure. Postinfectious conditions and lupus are among the many causes of glomerulonephritis. Polycystic kidney disease is a hereditary cause of chronic kidney disease wherein both kidneys have multiple cysts. Use of analgesics such as acetaminophen (Tylenol) and ibuprofen (Motrin, Advil) regularly over long durations of time can cause analgesic nephropathy, another cause of kidney disease. Certain other medications can also damage the kidneys. Clogging and hardening of the arteries (atherosclerosis) leading to the kidneys causes a condition called ischemic nephropathy, which is another cause of progressive kidney damage. Obstruction of the flow of urine by stones, an enlarged prostate, strictures (narrowings), or cancers may also cause kidney disease. Other causes of chronic kidney disease include HIV infection, sickle cell disease, heroin abuse, amyloidosis, kidney stones, chronic kidney infections, and certain cancers. If one has any of the following conditions, they are at higher-than-normal risk of developing chronic kidney disease. One's kidney function may need to be monitored regularly.
- Diabetes mellitus type 1 or type 2
- High blood pressure
- High cholesterol
- Heart disease
- Liver disease
- Amyloidosis
- Sickle cell disease
- Systemic lupus erythematosus
- Vascular diseases such as arteritis, vasculitis, or fibromuscular dysplasia
- Vesicoureteral reflux (a urinary tract problem in which urine travels from the bladder the wrong way back toward the kidney)
- Require regular use of anti-inflammatory medications
- A family history of kidney disease
Chronic Kidney Disease Symptoms and When to Seek Medical Care:
The kidneys are remarkable in their ability to compensate for problems in their function. That is why chronic kidney disease may progress without symptoms for a long time until only very minimal kidney function is left. Because the kidneys perform so many functions for the body, kidney disease can affect the body in a large number of different ways. Symptoms vary greatly. Several different body systems may be affected. Notably, most patients have no decrease in urine output even with very advanced chronic kidney disease. Effects and symptoms of chronic kidney disease include:
- need to urinate frequently, especially at night (nocturia);
- swelling of the legs and puffiness around the eyes (fluid retention);
- high blood pressure;
- fatigue and weakness (from anemia or accumulation of waste products in the body);
- loss of appetite, nausea and vomiting;
- itching, easy bruising, and pale skin (from anemia);
- shortness of breath from fluid accumulation in the lungs;
- headaches, numbness in the feet or hands (peripheral neuropathy), disturbed sleep, altered mental status (encephalopathy from the accumulation of waste - -
- products or uremic poisons), and restless legs syndrome;
- chest pain due to pericarditis (inflammation around the heart);
- bleeding (due to poor blood clotting);
- bone pain and fractures; and
- decreased sexual interest and erectile dysfunction. When to Seek Medical Care:
Several signs and symptoms may suggest complications of chronic kidney disease. One should call a health care professional if they notice any of the following symptoms:
- change in energy level or strength;
- increased water retention (puffiness or swelling) in the legs, around the eyes, or - in other parts of the body;
- shortness of breath or change from normal breathing;
- nausea or vomiting;
- lightheadedness;
- bone or joint pain;
- easy bruising; or
- itching. If a woman has known kidney problems, she should see a health care professional right away if she knows or suspects that she is pregnant. See a health care practitioner as recommended for monitoring and treatment of chronic conditions such as diabetes, high blood pressure, and high cholesterol. The following signs and symptoms represent the possibility of a severe complication of chronic kidney disease and warrant a visit to the nearest hospital emergency department.
- Change in level of consciousness -- extreme sleepiness or difficult to awaken
- Severe fatigue
- Chest pain
- Difficulty breathing
- Severe nausea and vomiting
- Severe bleeding (from any source)
- Muscle weakness
Chronic Kidney Disease Diagnosis:
Chronic kidney disease usually causes no symptoms in its early stages. Only lab tests can detect any developing problems. Anyone at increased risk for chronic kidney disease should be routinely tested for development of this disease.
- Urine, blood, and imaging tests (X-rays) are used to detect kidney disease, as well as to follow its progress.
- All of these tests have limitations. They are often used together to develop a picture of the nature and extent of the kidney disease.
- In general, this testing can be performed on an outpatient basis. Urine tests:
Urinalysis: Analysis of the urine affords enormous insight into the function of the kidneys. The first step in urinalysis is doing a dipstick test. The dipstick has reagents that check the urine for the presence of various normal and abnormal constituents including protein. Then, the urine is examined under a microscope to look for red and white blood cells, and the presence of casts and crystals (solids). Only minimal quantities of albumin (protein) are present in urine normally. A positive result on a dipstick test for protein is abnormal. More sensitive than a dipstick test for protein is a laboratory estimation of the urine albumin (protein) and creatinine in the urine. The ratio of albumin (protein) and creatinine in the urine provides a good estimate of albumin (protein) excretion per day. Twenty-four hour urine tests: This test requires the patient to collect all of their urine for 24 consecutive hours. The urine may be analyzed for protein and waste products (urea nitrogen, and creatinine). The presence of protein in the urine indicates kidney damage. The amount of creatinine and urea excreted in the urine can be used to calculate the level of kidney function and the glomerular filtration rate (GFR). Glomerular filtration rate (GFR): The GFR is a standard means of expressing overall kidney function. As kidney disease progresses, GFR falls. The normal GFR is about 100 to 140 mL/min in men and 85 to 115 mL/min in women. It decreases in most people with age. The GFR may be calculated from the amount of waste products in the 24-hour urine or by using special markers administered intravenously. An estimation of the GFR (eGFR) can be calculated from the patient's routine blood tests. Patients are divided into five stages of chronic kidney disease based on their GFR (see Table 1 above). Blood tests:
Creatinine and urea (BUN) in the blood: Blood urea nitrogen and serum creatinine are the most commonly used blood tests to screen for and monitor renal disease. Creatinine is a product of normal muscle breakdown. Urea is the waste product of breakdown of protein. The level of these substances rises in the blood as kidney function worsens. Estimated GFR (eGFR): The laboratory or physician may calculate an estimated GFR using the information from a patient's blood work. It is important to be aware of one's estimated GFR and stage of chronic kidney disease. The physician uses the patient's stage of kidney disease to recommend additional testing and provide suggestions on management. Electrolyte levels and acid-base balance: Kidney dysfunction causes imbalances in electrolytes, especially potassium, phosphorus, and calcium. High potassium (hyperkalemia) is a particular concern. The acid-base balance of the blood is usually disrupted as well. Decreased production of the active form of vitamin D can cause low levels of calcium in the blood. Inability of failing kidneys to excrete phosphorus causes its levels in the blood to rise. Testicular or ovarian hormone levels may also be abnormal. Blood cell counts: Because kidney disease disrupts blood cell production and shortens the survival of red cells, the red blood cell count and hemoglobin may be low (anemia). Some patients may also have iron deficiency due to blood loss in their gastrointestinal system. Other nutritional deficiencies may also impair the production of red cells. Other tests:
Ultrasound: Ultrasound is often used in the diagnosis of kidney disease. An ultrasound is a noninvasive type of imaging test. In general, kidneys are shrunken in size in chronic kidney disease, although they may be normal or even large in size in cases caused by adult polycystic kidney disease, diabetic nephropathy, and amyloidosis. Ultrasound may also be used to diagnose the presence of urinary obstruction, kidney stones and also to assess the blood flow into the kidneys. Biopsy: A sample of the kidney tissue (biopsy) is sometimes required in cases in which the cause of the kidney disease is unclear. Usually, a biopsy can be collected with local anesthesia by introducing a needle through the skin into the kidney. This is usually done as an outpatient procedure, though some institutions may require an overnight hospital stay. Its a lot to take in but trust me its worth it...
