Kidney stones can form when urine contains too much of certain substances. These substances can create small crystals that become stones.
Nephrolithiasis occurs in all parts of the world, with a lower lifetime risk of 2-5% in Asia, 8-15% in the West, and 20% in Saudi Arabia.
Approximately 80-85% of stones pass spontaneously.
Approximately 20% of patients require hospital admission because of unrelenting pain, inability to retain enteral fluids, proximal urinary tract infection (UTI), or inability to pass the stone.
A ureteral stone associated with obstruction and upper UTI is a true urologic emergency. Complications include perinephric abscess, urosepsis, and death. Immediate involvement of the urologist is essential.
What is a kidney stone?
A kidney stone is a hard, crystalline mineral material formed within the kidney or urinary tract. Kidney stones are a common cause of blood in the urine (hematuria) and often severe pain in the abdomen, flank, or groin. Kidney stones are sometimes called renal calculi.
The condition of having kidney stones is termed nephrolithiasis. Having stones at any location in the urinary tract is referred to as urolithiasis, and the term ureterolithiasis is used to refer to stones located in the ureters.
Who is at risk for kidney stones?
Most urinary stones develop in people 20-49 years of age, and those who are prone to multiple attacks of kidney stones usually develop their first stones during the second or third decade of life.
In residents of industrialized countries, kidney stones are more common than stones in the bladder. The opposite is true for residents of developing areas of the world, where bladder stones are the most common. This difference is believed to be related to dietary factors.
A family history of kidney stones is also a risk factor for developing kidney stones.
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. 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.
Dehydration from reduced fluid intake or strenuous exercise without adequate fluid replacement increases the risk of kidney stones.
Kidney stones can also result from infection in the urinary tract; these are known as struvite or infection stones.
A number of different medical conditions can lead to an increased risk for developing kidney stones:
Other conditions associated with an increased risk of kidney stones include hyperparathyroidism & Chronic diseases such as diabetes and high blood pressure (hypertension) are also associated with an increased risk of developing kidney stones
Some medications also raise the risk of kidney stones. These medications include some diuretics, calcium-containing antacids, and the protease inhibitor indinavir (Crixivan), a drug used to treat HIV infection.
Dietary factors and practices may increase the risk of stone formation in susceptible individuals. In particular, inadequate fluid intake (dehydration) a high intake of animal protein,
a high-salt diet,
excessive sugar consumption,
excessive vitamin D supplementation,
possible excessive intake of oxalate-containing foods such as spinach.
What are kidney stones symptoms and signs?
While some kidney stones may not produce symptoms (known as "silent" stones), people who have kidney stones often report.
Sudden onset of excruciating, cramping pain in their low back and/or side, groin, or abdomen.
Changes in body position do not relieve this pain. The abdominal, groin, and/or back pain typically waxes and wanes in severity, characteristic of colicky pain (the pain is sometimes referred to as renal colic).
It may be so severe that it is often accompanied by nausea and vomiting. Kidney stones also characteristically cause blood in the urine.
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.
How are kidney stones diagnosed?
Imaging tests are usually done to confirm the diagnosis.
A helical CT scan without contrast material is the most common test to detect stones or obstruction within the urinary tract.
Formerly, an intravenous pyelogram (IVP; an X-ray of the abdomen along with the administration of contrast dye into the bloodstream) was the test most commonly used to detect urinary tract stones, but this test has a greater risk of complications.
Helical CT scans have been shown to be a significantly more effective diagnostic tool than the IVP in the diagnosis of kidney or urinary tract stones.
In pregnant women or those who should avoid radiation exposure, an ultrasound examination may be done to help establish the diagnosis.
What is the treatment for kidney stones?
Most kidney stones eventually pass through the urinary tract on their own within 48 hours, with ample fluid intake.
Home care in this case includes the consumption of plenty of fluids. Ibuprofen (Advil) may be used as an anti-inflammatory medication if there is no contraindication to its use. If further pain medication is needed, stronger narcotic pain medications may be recommended.
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.
Surgical techniques have also been developed to remove kidney stones when other treatment methods are not effective. This may be done through a small incision in the skin (percutaneous nephrolithotomy) or through an instrument known as an ureteroscope passed through the urethra and bladder up into the ureter.