Kidney Stones
What are Kidney (Renal) stones?
Kidney stones (nephrolithiasis) are the result of a buildup of dissolved minerals and salts with a major component of Calcium Oxalate on the inner lining of the kidneys. Kidney stones can grow to the size of a golf ball while maintaining a sharp, crystalline structure. Whereas some stones can be so small that they pass unnoticed through the urinary tract. In some cases they can cause extreme pain as they are excreted lout of the body. The pain generated by the passing of kidney stones is called renal colic; the pain is caused by dilation, stretching and spasm because of the acute ureteral obstruction.
What cause the formation of kidney stones?
Formation of kidney stones is multi-factorial and they include:
1. Lack of fluid intake . When there is not enough water to dilute the uric acid which is a component of urine, the urine becomes more acidic.An excessively acidic environment in urine increases the chance of formation of kidney stones.
2. Certain diseases like Crohn's disease, urinary tract infections, renal tubular acidosis, hyperparathyroidism, medullary sponge kidney and Dent's disease increase the risk of kidney stones.
3. Kidney stones form when your urine contains more crystal-forming components like calcium, oxalate and uric acid than the fluid in your urine can dilute.
Types of Kidney stones
Risk factors for developing kidney stones
Kidney stones (nephrolithiasis) are the result of a buildup of dissolved minerals and salts with a major component of Calcium Oxalate on the inner lining of the kidneys. Kidney stones can grow to the size of a golf ball while maintaining a sharp, crystalline structure. Whereas some stones can be so small that they pass unnoticed through the urinary tract. In some cases they can cause extreme pain as they are excreted lout of the body. The pain generated by the passing of kidney stones is called renal colic; the pain is caused by dilation, stretching and spasm because of the acute ureteral obstruction.
What cause the formation of kidney stones?
Formation of kidney stones is multi-factorial and they include:
1. Lack of fluid intake . When there is not enough water to dilute the uric acid which is a component of urine, the urine becomes more acidic.An excessively acidic environment in urine increases the chance of formation of kidney stones.
2. Certain diseases like Crohn's disease, urinary tract infections, renal tubular acidosis, hyperparathyroidism, medullary sponge kidney and Dent's disease increase the risk of kidney stones.
3. Kidney stones form when your urine contains more crystal-forming components like calcium, oxalate and uric acid than the fluid in your urine can dilute.
Types of Kidney stones
- Calcium stones. Most kidney stones are calcium stones making up of calcium oxalate which is a naturally occurring substance found in food and is also produced by your liver. Nuts and chocolate for example have high oxalate content. Dietary factors, high doses of vitamin D, intestinal bypass surgery and metabolic disorders can increase the concentration of calcium or oxalate in urine. Calcium stones making up of calcium phosphate is more common in metabolic conditions such as renal tubular acidosis. It is also associated with certain migraine or with taking certain seizure medications for example topiramate.
- Struvite stones form in response to urinary tract infection. These stones can grow quickly and become big, sometimes with few symptoms or little warning.
- Uric acid stones. Uric acid stones can form in people who don't drink enough fluids, in those who lose too much fluid, those who eat a high-protein diet and those who have gout disease. Certain genetic factors can also increase your risk of forming uric acid stones.
- Cystine stones. These stones form in people with a hereditary disorder that causes the kidneys to excrete too much amino acids (cystinuria).
Risk factors for developing kidney stones
- Family or personal history. If someone in your family or yourself has kidney stones before then you're more likely to develop stones.
- Gender: kidney stones are more likely to be seen in males than females.
- Diet: Eating a diet that's high in protein, sodium (salt) increases your risk of kidney stones.
- Dehydration. Not drinking enough water each day can increase your risk of kidney stones.
- Obesity
- Digestive diseases and surgery. Gastric bypass surgery, inflammatory bowel disease or chronic diarrhea can affect your absorption of calcium and water, increasing the levels of stone-forming elements in your urine.
- Other medical conditions. Renal tubular acidosis, cystinuria, hyperparathyroidism and urinary tract infections increase the risk of kidney stone formation too
- Medications: Topamax is a drug commonly prescribed to treat seizures and migraine may increase the risk of kidney stone formation. High doses of vitamin D and calcium supplements may increase calcium levels which can contribute to kidney stones. (Only take what is prescribed do not over take)
Signs and symptoms of Kidney stones
A kidney stone may not cause any symptoms until it moves into the ureter. The symptoms include:
Complications of Kidney stones
Sometimes Kidney stones may lead to complications, including blockage of ureter connecting the kidney to the bladder. That results in the obstruction of the path of excretion of the urine (Retention of urine). Stones can also results in higher risk of kidney infection and chronic kidney disease.
Diagnosis of kidney stones
As the clinical symptoms are very classical hence diagnosis maybe made via symptoms alone. But confirmatory test is conducted to localize the stone and to see the size of the stone. A physical examination may reveal colicky pain in the groin and the lower near the kidneys. The tests that are done include:
A kidney stone may not cause any symptoms until it moves into the ureter. The symptoms include:
- severe pain in the side and back (flank) below the ribs, radiating down the abdomen to the groin (renal colic)
- blood in urine
- vomiting and nausea
- urine sample may show blood and white cells
- painful urination
- urge to urinate
- cloudy smelly urine if there's infection
- urine frequency but in small amounts each time
- fever and chills if there is an infection
Complications of Kidney stones
Sometimes Kidney stones may lead to complications, including blockage of ureter connecting the kidney to the bladder. That results in the obstruction of the path of excretion of the urine (Retention of urine). Stones can also results in higher risk of kidney infection and chronic kidney disease.
Diagnosis of kidney stones
As the clinical symptoms are very classical hence diagnosis maybe made via symptoms alone. But confirmatory test is conducted to localize the stone and to see the size of the stone. A physical examination may reveal colicky pain in the groin and the lower near the kidneys. The tests that are done include:
- Blood testing. Full blood count may reveal raised white blood cells in a patient with concurrent infection. Some may have high calcium or uric acid the blood test. Renal panel will also aid the doctor to make sure there is no chronic renal disease (complications).
- Urine testing. Urine analysis will reveal if there is microscopic red blood cells and white blood cells. The 24-hour urine collection test collected may show whether there are stone-forming minerals.
- Imaging tests: Done to show the location of kidney stones in your urinary tract. Simple abdominal X-rays (KUB) to assess stone's size, shape, composition, location of urinary calculi but which can miss small kidney stones. Ultrasound kidneys is a noninvasive test to see the presence of a renal stone and the presence of hydronephrosis or ureteral dilation which are complications. Intravenous urography (IVU) which involves injecting a dye into a vein and taking X-rays for clear visualization of entire urinary system and to identify the stone. Noncontrast CT scan is the imaging modality of choice for assessment of urinary tract disease. A CT scan will ascertain the state of the ureter, bladder, and kidneys, whether a stone exists, the kidney stone's exact size and location, whether there is an obstruction of the urinary tract and the state of other organs in the area.
- Analysis of passed stones. Lab analysis to analyze the makeup of your kidney stones so as to determine what's causing your kidney stones and to plan what can prevent more kidney stones.
Treatment for kidney stones
The treatment depends on the type of stone, the size, the location and the cause.
Small stones < 5mm
Most urinary stones that are small (<5mm) will pass out of the body spontaneously without need for surgery.
Large stones > 6mm
Kidney stones that can't be treated with conservative measures because they're too large to pass on their own or when they cause complications like bleeding (gross hematuria), kidney damage (Chronic renal disease) and urinary tract infections. That is when more invasive treatments are required. The options are:
For those who have uric acid stones, one should control their diet and take medications that reduce uric acid concentration.
The treatment depends on the type of stone, the size, the location and the cause.
Small stones < 5mm
Most urinary stones that are small (<5mm) will pass out of the body spontaneously without need for surgery.
- Drinking 2-3 liters of water a day will help flush out the stone
- Pain medications should there be pain during colic or when the stone passes out
- Anti-emetic: may help overcome the nausea feeling/vomiting
- Medications like alpha blockers may be prescribed to relax the muscles in your ureter and help you pass the kidney stone more quickly and with less pain.
- Antibiotics are only given if there is urinary tract infection.
Large stones > 6mm
Kidney stones that can't be treated with conservative measures because they're too large to pass on their own or when they cause complications like bleeding (gross hematuria), kidney damage (Chronic renal disease) and urinary tract infections. That is when more invasive treatments are required. The options are:
- Medications for ureteric stones <10mm which are not causing upper tract obstruction or significant symptoms can be tried. Failure of stones to pass out after 4 to 6 weeks of medical treatment will necessitate other interventions to remove these stones. Medications like alpha blockers (tamsulosin) can be used.
- Extracorporeal shock wave lithotripsy (ESWL): uses sound waves to create strong vibrations (shock waves) that break the stones into tiny pieces that can be passed in your urine. The session lasts about 45 to 60 minutes and can cause moderate pain thus it is done after taking analgesics. After the procedure there maybe blood in the urine, bruising on the back or abdomen, bleeding around the kidney and other adjacent organs and discomfort as the stone fragments pass through the urinary tract.
- Ureterorenoscopy and laser lithotripsy (URS & LL): for stones less than 2 cm, a ureteroscope (thin lighted tube equipped with camera) is passed through your urethra and bladder to your ureter to remove a smaller stone in your ureter or kidney. Once the stone is located, the stones may then be shattered using a Holmium laser probe under direct vision and the fragments retrieved out of the ureter using special stone baskets. A temporary plastic stent maybe left in the ureter to relieve swelling and promote healing. The stent is subsequently removed using a cystoscope 4-6 weeks after the initial procedure. This is as an outpatient procedure done under general anaesthesia. Pain after this procedure usually resolves after 2-3 days, although blood in the urine may take longer to clear up.
- Percutaneous nephrolithotomy (PCNL) is a procedure to remove larger stones > 2 cm and when ESWL is not suitable. It is done under general anaesthesia, a small incision will be done in your back. Then Rigid and flexible nephroscopes are inserted to locate the stones, which are then shattered and removed under X-ray guidance. A small nephrostomy tube is left in the kidney for a few days till residual bleeding clears up.
- Open surgery is now seldom carried out, It's only usually used if there's a very large stone or abnormal anatomy.
- Parathyroid gland surgery. Some calcium phosphate stones are caused by overactive parathyroid glands. When the parathyroid glands produce too much parathyroid hormone in a condition called hyperparathyroidism, your calcium levels can become too high and cause kidney stones to form. Removing the growth from the gland in this case will stop the formation of kidney stones.
For those who have uric acid stones, one should control their diet and take medications that reduce uric acid concentration.
Prevention
- Drink more water: For people with history of kidney stones, drink at least 2 liters - 3 liters of water a day
- Eat fewer oxalate-rich foods. Those who have calcium oxalate stones, limit foods rich in oxalates which include beets, spinach, , sweet potatoes, nuts, tea, chocolate, black pepper and soy products.
- Choose a diet low in salt and animal protein
- Continue eating calcium-rich foods, but use caution with calcium supplements. Calcium in food doesn't increase your risk of developing kidney stones. Do not take too much calcium supplements, take the dose recommended by the doctor.
- Low purine diet for those with history of gout and who are at risk of developing uric acid stones.