What are Kidney Stones (Renal Calculi, Nephrolithiasis)?
Kidney stones are made of salts and minerals in the urine that stick together to form small "pebbles." A kidney stone is a hard, crystalline mineral material formed within the kidney or urinary tract. They can be as small as grains of sand or as large as golf balls. They may stay in your kidneys or travel out of your body through the urinary tract. The urinary tract is the system that makes urine and carries it out of your body.
Kidney stones are a common cause of blood in the urine and often severe pain in the abdomen, flank or groin. Kidney stones are sometimes called renal calculi. One in every 20 people develops a kidney stone at some point in their life. The condition of having kidney stones is termed nephrolithiasis. Having stones at any location in the urinary tract is referred to as urolithiasis.
What causes kidney stones?
Kidney stones form when there is a decrease in urine volume and/or an excess of stone-forming substances in the urine or Kidney stones form when a change occurs in the normal balance of water, salts, minerals and other things found in urine. The most common type of kidney stone contains calcium in combination with either oxalate or phosphate. Other chemical compounds that can form stones in the urinary tract include uric acid and the amino acid cystine.
The most common cause of kidney stones is not drinking enough water. Try to drink enough water to keep your urine clear (about 8 to 10 glasses of water a day). Some people are more likely to get kidney stones because of a medical condition or family history. Dehydration from reduced fluid intake or strenuous exercise without adequate fluid replacement increases the risk of kidney stones. Obstruction to the flow of urine can also lead to stone formation. Kidney stones can also result from infection in the urinary tract; these are known as struvite or infection stones.
Kidney stones are about four times as likely to occur in men as in women. The prevalence of kidney stones begins to rise when men reach their 40s and it continues to climb into their 70s. People who have already had more than one kidney stone are prone to develop more stones. A family history of kidney stones is also a risk factor for developing kidney stones.
What are kidney stones symptoms?
Some people with kidney stones feel no symptoms (known as "silent" stones), while others can feel severe, sharp pain when the stone migrates into the urinary tract. The pain - sometimes lasting for hours at a time - tends to start in the lower back or side, and often moves to the groin. Nausea and vomiting, fever (which may indicate the presence of an infection), blood in the urine, burning pain during urination and blocked urine flow are among other possible symptoms. If infection is present in the urinary tract along with the stones, there may be fever and chills. Sometimes, symptoms such as difficulty urinating, urinary urgency, penile pain, or testicular pain may occur due to kidney stones. Kidney stones can usually be detected with one of several imaging studies and blood and urine tests can help to determine what is causing the stone and how it should be treated.
What is the treatment for kidney stones?
When kidney stones are detected, patients are advised to drink ample amounts of water - 2-3 quarts a day - in an effort to get the stone to pass. A special diet is often prescribed based on the type of stone. Approximately 90 percent of stones will pass on their own within a few weeks, particularly if they are small (4 mm or less); larger stones may require treatment. Pain medications are used for symptom relief. When over-the-counter medications are not sufficient for pain control, narcotics may be prescribed. Intravenous pain medications can be given when nausea and vomiting are present.
There are several factors which influence the ability to pass a stone. These include the size of the person, prior stone passage, prostate enlargement, pregnancy, and the size of the stone. A 4 mm stone has an 80% chance of passage while a 5 mm stone has a 20% chance. Stones larger than 9 mm-10 mm rarely pass without specific treatment.
For kidney stones that do not pass on their own, a procedure called lithotripsy is often used. In this procedure, shock waves are used to break up a large stone into smaller pieces that can then pass through the urinary system.
For patients who require surgical removal, the stone can be removed by inserting an ureteroscope instrument directly into the kidney through a small incision in the back (percutaneous removal), or into the bladder and ureter to pull out or break down the stone.
How can kidney stones be prevented?
Rather than having to undergo treatment, it is best to avoid kidney stones in the first place when possible. It can be especially helpful to drink more water, since low fluid intake and dehydration are major risk factors for kidney stone formation.
Depending on the cause of the kidney stones and an individual's medical history, dietary changes or medications are sometimes recommended to decrease the likelihood of developing further kidney stones. If one has passed a stone, it can be particularly helpful to have it analyzed in a laboratory to determine the precise type of stone so specific prevention measures can be considered.
How Kidney Works?
The kidneys are a pair of vital organs that perform many functions to keep the blood clean and chemically balanced. In humans, the kidneys are located in the abdominal cavity, in a space called the retroperitoneum. There are two, one on each side of the spine. The left kidney lies a little higher than the right kidney. They are bean-shaped, about 4 in. (10 cm) long and about 21/2 in. (6.4 cm) wide.
Understanding how the kidneys work can help a person keep them healthy. The main purpose of the kidney is to separate urea, mineral salts, toxins and other waste products from the blood. The kidneys also conserve water, salts and electrolytes. At least one kidney must function properly for life to be maintained.
The kidneys are sophisticated reprocessing machines. Every day, a person's kidneys process about 200 quarts of blood to sift out about 2 quarts of waste products and extra water. The wastes and extra water become urine, which flows to the bladder through tubes called ureters. The bladder stores urine until releasing it through urination.
The body uses food for energy and self-repairs. After the body has taken what it needs from food, wastes are sent to the blood. If the kidneys did not remove them, these wastes would build up in the blood and damage the body. The actual removal of wastes occurs in tiny units inside the kidneys called nephrons. Each kidney has about a million nephrons.
In addition to removing wastes, the kidneys release three important hormones:
- Erythropoietin (EPO), which stimulates the bone marrow to make red blood cells
- Renin, which regulates blood pressure
- Calcitriol, the active form of vitamin D, which helps maintain calcium for bones and for normal chemical balance in the body
What happenes during complete Kidney failure?
Total or nearly total and permanent kidney failure is called ESRD (End-stage Renal Disease). If a person's kidneys stop working completely, the body fills with extra water and waste products. This condition is called uremia. Hands or feet may swell. A person will feel tired and weak because the body needs clean blood to function properly.
Untreated uremia may lead to seizures or coma and will ultimately result in death. A person whose kidneys stop working completely will need to undergo dialysis or kidney transplantation.
Diabetes is the most common cause of kidney failure, accounting for more than 40 percent of new cases. High blood pressure (Hypertension) is a major factor in the development of kidney problems in people with diabetes.