Kidney stones are a hard, crystalline mineral material formed within the kidney, usually when there is a decrease in urine volume and/or an excess of stone-forming substances in the urine. Passing kidney stones can be very painful, but the stones usually do not cause permanent damage.
Kidney Stones Causes and Risk Factors
There are different types of kidney stones, each with different causes:
- Calcium stones (80 percent of stones) – The most common type of kidney stone, calcium stones can be caused by excess calcium in the urine – which can be caused by high doses of vitamin D, intestinal bypass surgery and several other metabolic disorders – or by the way the body handles calcium. Doctors do not recommend restricting calcium from the diet, as restricting dietary calcium can adversely affect bone health and may actually increase kidney stone risk.
- Uric acid stones (5 to 10 percent of stones) – Uric acid stones may be caused by dehydration (not drinking enough fluids or too much fluid loss), a diet high in animal protein and low in fruits and vegetables, obesity, being overweight, Type 2 diabetes, gout or certain genetic factors.
- Struvite stones (10 percent of stones) – Struvite stones are related to chronic urinary tract infections (UTIs). These stones are often large, with branches, and often grow very fast, often with few symptoms and little warning.
- Cystine stones (less than 1 percent of stones) – These stones form in people with a rare hereditary disorder that causes the kidneys to excrete too much of certain amino acids (cystinuria).
Factors that can increase the risk of developing kidney stones include:
- Diets high in sodium, sugar or animal protein
- Digestive conditions that cause diarrhea, such as Crohn's Disease or ulcerative colitis, or surgeries, such as gastric bypass surgery
- Medical conditions, such as renal tubular acidosis, cystinuria, hyperparathyroidism, certain medications and some urinary tract infections
- Certain medications, vitamins and supplements
- Family or personal history of kidney stones
Symptoms of Kidney Stones
When in the kidney, stones often do not cause symptoms and can go undiagnosed. When a stone leaves the kidney, it travels to the bladder through the ureter, where it may become lodged. When the stone blocks the flow of urine out of the kidney, it can cause the kidney to swell (hydronephrosis), often causing a lot of pain.
Common symptoms of kidney stones include:
- A sharp, cramping pain in the back and side, often moving to the lower abdomen or groin
- Pain that starts suddenly and comes in waves, varying in intensity as the body tries to “pass” the stone
- Intense need to urinate
- Frequent urination
- Painful urination
- Urinating in small amounts
- Urine that is pink, red or brown due to blood
- Cloudy or foul-smelling urine
- Nausea and vomiting
- Fever and chills, if infection is present
- In men, possible pain at the tip of the penis
Diagnosing Kidney Stones
If a kidney stone is suspected, your doctor may order diagnostic tests and procedures, including:
- Blood tests, to measure calcium or uric acid levels
- Urine testing (urinalysis), to measure levels of stone-forming or stone-preventing substances in the urine
- Imaging tests, including abdominal X-ray, computerized tomography (CT) scan, ultrasound or others
- Analysis of passed stones, to help your doctor determine the cause of the stones to prevent recurrence
Treatment for Kidney Stones
Treatment varies, based on the type and cause of the stone.
Small stones can be passed, without invasive treatment, by drinking water to flush out the urinary tract, taking over-the-counter pain relievers for pain while passing the stone, and through a medication (Tamsulosin, Flomax) that relaxes the ureter, making it easier for the stone to pass.
Larger stones may require more extensive treatment, including:
- Shock wave lithotripsy (SWL) – Procedure, usually performed under some type of anesthesia, that uses sound waves to create strong vibrations (shock waves) that break down the stones so they may be passed in the urine
- Ureteroscopy (URS) – Minimally-invasive surgery, often performed under general or local anesthesia, in which a doctor uses a thin lighted tube (uteroscope) equipped with a camera to locate and remove a smaller stone in the ureter or kidney
- Percutaneous nephrolithotomy (PCNL) – Minimally-invasive surgery, performed under general anesthesia, in which the surgeon uses instruments, inserted through a rigid telescope (nephroscope), to break up and suction a large stone(s) out of the kidney
The skilled, board-certified general surgeons affiliated with Memorial Hermann Memorial City Medical Center specialize in abdominal surgeries.
To schedule an appointment with a physician affiliated with Memorial Hermann, click here or call 713-222-CARE (2273).