The kidneys are bean-shaped organs that serve several essential regulatory roles in vertebrate animals. They remove excess organic molecules (e.g., glucose) from the blood, and it is by this action that their best-known function is performed: the removal of waste products of metabolism (e.g., urea, though 90% of this is reabsorbed along the nephron.) They are essential in the urinary system and also serve homeostatic functions such as the regulation of electrolytes, maintenance of acid-base balance, and regulation of blood pressure (via maintaining salt and water balance). They serve the body as a natural filter of the blood, and remove water soluble wastes, which are diverted to the urinary bladder. In producing urine, the kidneys excrete wastes such as urea and ammonium, and they are also responsible for the reabsorption of water, glucose, and amino acids. The kidneys also produce hormones including calcitriol, erythropoietin, and the enzyme renin, the latter of which indirectly acts on the kidney in negative feedback..
Located at the rear of the abdominal cavity in the retroperitoneum, the kidneys receive blood from the paired renal arteries, and drain into the paired renal veins. Each kidney excretes urine into a ureter, itself a paired structure that empties into the urinary bladder.
Renal physiology is the study of kidney function, while nephrology is the medical specialty concerned with kidney diseases. Diseases of the kidney are diverse, but individuals with kidney disease frequently display characteristic clinical features. Common clinical conditions involving the kidney include the nephritic and nephrotic syndromes, renal cysts, acute kidney injury, chronic kidney disease, urinary tract infection, nephrolithiasis, and urinary tract obstruction. Various cancers of the kidney exist; the most common adult renal cancer is renal cell carcinoma. Cancers, cysts, and some other renal conditions can be managed with removal of the kidney, or nephrectomy. When renal function, measured by glomerular filtration rate, is persistently poor, dialysis and kidney transplantation may be treatment options. Although they are not normally harmful, kidney stones can be painful, and repeated, chronic formation of stones can scar the kidneys. The removal of kidney stones involves ultrasound treatment to break up the stones into smaller pieces, which are then passed through the urinary tract. One common symptom of kidney stones is a sharp to disabling pain in the medial/lateral segments of the lower back or groin.
Kidney disease usually affects both kidneys. If the kidneys' ability to remove and regulate water and chemicals is seriously damaged by disease, waste products and excess fluid buildup occur, causing severe swelling and symptoms of uremia (kidney failure).
There are many different types and causes of kidney disease. These can be characterized as hereditary, congenital or acquired.
• Hereditary Disorders
These can be transmitted to both males and females, and generally produce clinical symptoms from teenage years to adulthood. The most prevalent hereditary kidney condition is polycystic kidney disease. Other hereditary conditions include Alport's syndrome, hereditary nephritis, primary hyperoxaluria and cystinuria.
• Congenital Disease
This usually involves some malformation of the genitourinary tract, usually leading to some type of obstruction which subsequently produces infection and/or destruction of kidney tissue. The destruction can eventually progress to chronic kidney failure.
• Acquired Kidney Disease
These diseases are numerous, the general term being nephritis (meaning inflammation of the kidney). The most common type of nephritis is glomerulonephritis, and again, this has many causes.
• Kidney Stones
These are very common, and when they pass, the pain can be extremely severe in the side and back. Stone formation can be an inherited disorder, secondary to a malformation and/or infection in the kidney, or can occur without any prior problem. The pain can appear suddenly and in waves, and then disappear rapidly when the stone is passed.
• Nephrotic Syndrome
This refers to a large protein loss in the urine [frequently in association with low blood protein (albumin) levels, an elevated blood cholesterol and severe retention of body fluid, causing swelling (edema)]. This disease can be a primary disorder of the kidney or secondary to an illness, affecting many parts of the body (for example diabetes mellitus).
• Long-standing High Blood Pressure (hypertension)
This can cause kidney disease itself or can be a result of a kidney disorder. Uncontrolled high blood pressure can accelerate the natural course of any underlying kidney disease.
• Diabetes
Long standing diabetes can lead to kidney failure. However, tight control of blood glucose levels over the years may reduce those complications.
• Drugs and Toxins
Certain medications, toxins, pesticides and "street" drugs (i.e., heroin) can also produce kidney damage.
• Causes
Unfortunately, the cause of many kidney diseases is still unknown, but controlling high blood pressure and diabetes can reduce the risk of many kidney diseases.
• Symptoms
Although many forms of kidney disease do not produce symptoms until late in the course of the disease, there are at least six warning signs that may indicate kidney disease: 1. Burning or difficulty during urination 2. An increase in the frequency of urination 3. Passage of blood in the urine 4. Puffiness around the eyes, swelling of the hands and feet 5. Pain in the small of the back just below the ribs 6. High blood pressure
• Diagnosis
Your doctor will obtain a complete medical history and perform a physical exam. He or she may recommend blood tests and certain urine tests, which can provide much information about your kidney function.
• Treatment
Some kidney diseases can be successfully treated and others progress to advanced kidney failure, requiring dialysis and/or transplantation. For example, kidney infections and kidney stones can often be successfully treated. Chronic inflammation of the glomerulus (glomerulonephritis) is the most common kidney disease, which slowly progresses to kidney failure. Your doctor may recommend certain medications or suggest a specific diet for you.
The key to prevention or delay of severe kidney disease is early detection and aggressive intervention -- while there's still time to slow down the progression to kidney failure. Medical care with early intervention can change the course of chronic kidney disease and help prevent the need for dialysis or a kidney transplant.
Diabetes and high blood pressure account for two thirds of all cases of chronic kidney disease. By aggressively managing diabetes and high blood pressure with diet, exercise, and medications, you may be able to prevent kidney failure and help keep as much kidney function as possible.
• Recommended Related to
Creatinine and Creatinine Clearance Blood Tests Creatinine is a waste product from the normal breakdown of muscle tissue. As creatinine is produced, it's filtered through the kidneys and excreted in urine. Doctors measure the blood creatinine level as a test of kidney function. The kidneys' ability to handle creatinine is called the creatinine clearance rate, which helps to estimate the glomerular filtration rate (GFR) -- the rate of blood flow through the kidneys.
• Know Your Risks for Kidney Disease
Since diabetes and high blood pressure put you at risk of kidney disease, know where you stand with these risks. Do you have diabetes or high blood pressure? If so, are they under control? If you can, find out if diabetes, hypertension, or kidney disease runs in your family. Certain ethnic groups, such as African-Americans, Hispanics, Pacific Islanders, and Native Americans are at higher risk of chronic kidney disease, as are senior citizens.
• Get Tested Regularly
At your next checkup, and at least within the next year if you haven't had these tests done:
• Ask for a urine test to see if you have excess protein, glucose, or blood in the urine.
• Ask for a blood pressure reading, to see if your blood pressure is elevated.
• Ask for a fasting blood glucose test, to see if you have too much glucose (sugar) in your blood. Another blood test that can be used to determine diabetes is a hemoglobin A1C which will indicate your average blood glucose level over the past two to three months.
• Ask for a creatinine test. This blood test measures the amount of waste from muscle activity. When the kidneys are not working properly, the creatinine rises.
If any of these tests are abnormal, your health care provider will need to do other tests to more clearly define the problem.
• Control Diabetes
If you have diabetes, work with your health care provider to keep your blood sugar levels under the best possible control. A program of diet, regular exercise, glucose monitoring, and medications to control blood sugars and protect kidney function can help.
• Control High Blood Pressure
If you have high blood pressure, work with your health care provider to get your blood pressure within target ranges. A program of diet, regular exercise, and medications can help.
• Consider Seeing a Nephrologist
If you've already lost some kidney function, or your health care provider tells you that you're likely to have more kidney damage in the future, ask for a referral to a nephrologist (a kidney disease specialist). A nephrologist can provide specialized testing, evaluate your condition, and talk with you about possible ways to slow down the progress of kidney disease.
Most people are not aware of the fact that kidney diseases can be silent killers. They may not show any symptoms for a long time till the situation becomes critical. (Why is it silent?) Even young people are now prone to it. It is important to recognize the symptoms of kidney diseases to catch them early. There are many reasons why kidney disease is caused. The most common causes are diabetes and hypertension. Even an unhealthy lifestyle with a high calorie diet, certain medicines. lots of soft drinks and sugar consumption can also cause kidney damage. Here is a list of twelve symptoms which could indicate something is wrong with your kidney:.
• Changes in your urinary function: The first symptom of kidney disease is changes in the amount and frequency of your urination. There may be an increase or decrease in amount and/or its frequency, especially at night. It may also look more dark coloured. You may feel the urge to urinate but are unable to do so when you get to the restroom.
• Difficulty or pain during voiding: Sometimes you have difficulty or feel pressure or pain while voiding. Urinary tract infections may cause symptoms such as pain or burning during urination. When these infections spread to the kidneys they may cause fever and pain in your back. Blood in the urine: This is a symptom of kidney disease which is a definite cause for concern. There may be other reasons, but it is advisable to visit your doctor in case you notice it. Swelling: Kidneys remove wastes and extra fluid from the body. When they are unable to do so, this extra fluid will build up causing swelling in your hands, feet, ankles and/or your face. Read more about swelling in the feet.
• Extreme fatigue and generalised weakness: Your kidneys produce a hormone called erythropoietin which helps make red blood cells that carry oxygen. In kidney disease lower levels of erythropoietin causes decreased red blood cells in your body resulting in anaemia. There is decreased oxygen delivery to cells causing generalised weakness and extreme fatigue. Read more about the reasons for fatigue. Dizziness & Inability to concentrate: Anaemia associated with kidney disease also depletes your brain of oxygen which may cause dizziness, trouble with concentration, etc.
• Feeling cold all the time: If you have kidney disease you may feel cold even when in a warm surrounding due to anaemia. Pyelonephritis (kidney infection) may cause fever with chills. Skin rashes and itching: Kidney failure causes waste build-up in your blood. This can causes severe itching and skin rashes.
• Ammonia breath and metallic taste: Kidney failure increases level of urea in the blood (uraemia). This urea is broken down to ammonia in the saliva causing urine-like bad breath called ammonia breath. It is also usually associated with an unpleasant metallic taste (dysgeusia) in the mouth.
• Nausea and vomiting: The build-up of waste products in your blood in kidney disease can also cause nausea and vomiting. Read 13 causes for nausea.
• Shortness of breath: Kidney disease causes fluid to build up in the lungs. And also, anaemia, a common side-effect of kidney disease, starves your body of oxygen. You may have trouble catching your breath due to these factors.
• Pain in the back or sides: Some cases of kidney disease may cause pain. You may feel a severe cramping pain that spreads from the lower back into the groin if there is a kidney stone in the ureter. Pain may also be related to polycystic kidney disease, an inherited kidney disorder, which causes many fluid- filled cysts in the kidneys. Interstitial cystitis, a chronic inflammation of the bladder wall, causes chronic pain and discomfort.
Read more about causes, symptoms, diagnosis and treatment of kidney disease.
It is important to identify kidney disease early because in most cases the damage in the kidneys can’t be undone. To reduce your chances of getting severe kidney problems, see your doctor when you observe one or more of the above symptoms. If caught early, kidney disease can be treated very effectively.
Chronic kidney disease (CKD): It is an age related gradual loss of kidney function and is often symptomless in the initial stages. Because loss of kidney function is gradual in CKD, there are different stages of CKD.
• Mild CKD: It occurs when the kidneys are damaged and cause slight decrease in GFR i.e., between 60 and 89 mL/min/1.73m2.
• Moderate CKD occurs when the GFR decreases further and may lie anywhere between 30 and 59 mL/min/1.73m2.
• In severe CKD, the filtration rate is reduced to 15-29 mL/min/1.73m2.
• Finally, when the GFR reduces below 15 mL/min/1.73m2, the stage of kidney failure is reached, where the patient needs dialysis for carrying out the filtration function.
Risk factors
Risk factors for kidney disease are grouped under modifiable and non-modifiable categories. Although you cannot do anything about the non-modifiable risk factors, lifestyle related factors can be controlled well in time to reduce the progression of kidney disease.
1. Diabetes
2. Hypertension or high blood pressure
3. Family history of kidney disease
4. Old age
5. Heart disease
6. Obesity
7. Recurrent urinary infection
8. Renal stone diseases
9. History of acute renal failure
10. Drug abuse/drug overdose
11. Race/Ethnicity
Diagnosis
Generally, with acute kidney disease you’ll develop symptoms based on which the doctor will recommend tests for assessing your kidney function. In chronic kidney disease, the symptoms are not seen in the early stages but the same tests if taken early can help diagnose kidney disease. Read about 3 good reasons to get a kidney check up done. When you go for an annual screening of your kidney function, you will have to undergo some or all of the following tests:
1. Blood tests: Several markers in the blood can help identify the actual kidney function. Urea and creatinine are the gold standards to detect kidney disease.
2. Urine tests: The ratio of values for blood and urine marker can give the actual rate of clearance of kidneys.
3. Estimated GFR: eGFR is the estimate of filtration rate of the kidneys based on a formula that include serum creatinine values along with correction factors like age, gender and race.
4. Imaging tests: Imaging test like renal ultrasound uses ultrasonic waves to analyse the size and shape of the kidneys to identify renal injury and changes in filtration capacity of the kidneys. Here are 8 tests for checking if your kidneys are functioning fine.
Why should I be checked for kidney disease?
Diabetes and high blood pressure can damage the kidneys and lead to kidney disease. You need to get checked for kidney disease if you have one of these conditions. Here are some other reasons to get checked: Ea rly kidney disease has no signs or symptoms. The only way to know if you have kidney disease is to get checked for it. Kidney disease usually does not go away. It may get worse over time and can lead to kidney failure. If your kidneys fail, you may need to go on dialysis or have a kidney transplant to maintain health. K idney disease can be treated. The sooner you know you have kidney disease, the sooner you can get treatment to help delay or prevent kidney failure. Treating kidney disease may also help prevent heart disease.