What is Renal Stone?
The kidneys are a pair of organs that are primarily responsible for filtering metabolites and minerals from the circulatory system. These secretions are then passed on to the bladder and out of the body as urine. Kidney stones, also called Renal Calculi (calculi means “pebbles” in Latin), are solid, crystal formations of dissolved minerals in the urine. Other names for this disease are Nephrolithiasis or Urolithiasis. These terms refer to the presence of calculi in the kidneys and urinary tract respectively. One in every 20 people develops a kidney stone at some point in their life. Renal stone is a hereditary disorder.
Symptoms of Renal Stone
Size of renal stone: While discussing the symptoms of Renal Stone, we have to take into consideration the size of the renal stone as this would have an impact on the symptoms. The size can vary from as small as a grain of sand to as large as a golf ball. The tiny ones pass out with urine as a matter of course and do not cause any discomfort. But if the size is about 2 to 3 millimeters, then they can cause obstruction of the ureter.
Resultant symptoms are:
a) Postrenal azotemia – obstruction of the ureter
b) Spasms of the renal muscles
c) Severe episodic pain in groin, flank and lower abdomen
d) Abdominal distention
e) Excruciating, cramping pain in the lower back
f) Renal colic with nausea and vomiting
g) Hematuria – blood in the urine due to damage to lining of urinary tract
h) Pyuria – pus in the urine
i) Oliguria – reduced volume of urine due to the obstruction
j) Hydronephrosis – swelling of the kidney suggesting a stone is blocking the outflow of urine
k) Dribbling of urine
l) Loss of appetite
m) Weight loss
n) Fever and chills (if urinary infection also exists).
Diagnosis of Renal Stone
Diagnosis of Renal stone would be to look for a specific pattern or groups of symptoms:
Physical examination: The doctor will diagnose renal stone or kidney stone on the basis of location and severity of pain. The pain will typically be colic in nature, i.e. spasmodic. The pain in the back will be present if there is obstruction in the ureter.
X-rays: Kidney stones are radio-opaque, hence can be detected very clearly with the help of abdominal X-rays. That would include X-rays of kidneys, ureters and bladder, referred to as KUB. But almost 10% of the kidney stones do not have sufficient calcium to be seen with standard X-rays.
Helical CT scan and IVP: The Helical Computer Tomography scan, without staining material, is the most common test to detect stones or obstruction within the urinary tract. This method of diagnosis is preferred to the Intra-Venous Pyelogram (IVP) where a contrast dye is administered into the bloodstream. The diagnosis is more accurate with Helical CT scan but it also involves higher exposure to radiation and higher cost. Helical CT scan is undertaken only if other tests give negative results despite suspected kidney stone.
Ultrasound: In pregnant women or those who should avoid radiation exposure, instead of Helical CT scan, an ultrasound examination is carried out in order to establish diagnosis. This would show the presence of hydronephrosis.
Blood/urine test: Blood test is carried out to check for proteins, excessive white cell count (neutrophilia) suggesting infection, red blood cells, bacteria, very high level of calcium (hypercalcaemia), and cellular casts and crystals. Urine test is carried out to eliminate other causes of pain. In severe cases a 24-hour urine collection is undertaken to measure total daily urinary volume and percentage of magnesium, sodium, uric acid, calcium-citrate, calcium-oxalate or calcium-phosphate.
Catching stones: If at home, the patient is advised to collect the stones usually through a tea strainer for further evaluation by a doctor.
Causes of Renal Stone
Kidney stones form due to a combination of causes like decrease in volume of urine, less intake of water after vigorous exercise, too much accumulation of calcium, inadequate intake of fluids, obstruction of flow of urine, etc. A number of different conditions can lead to kidney stones:
a) Gout results in an increased amount of uric acid in the urine and can lead to the formation of uric acid stones.
b) Hypercalciuria (high level of calcium in the urine) causes stones because too much calcium is absorbed from food and excreted into the urine, where it may form calcium phosphate or calcium oxalate stones.
c) Other conditions like hyperparathyroidism, renal tubular acidosis, cystinuria and hyperoxaluria, diabetes and hypertension are also associated with an increased risk of developing kidney stones.
d) People with inflammatory bowel disease or have undergone intestinal bypass or ostomy surgery are also more prone to developing kidney stones.
e) Some medications, like diuretics, calcium-containing antacids and the protease inhibitor Crixivan (indinavir), a drug used to treat HIV infection, can also increase risk of renal stones. Sometimes crystals form within the renal tract in some patients being treated with Indinavir, Sulfadiazine or Triamterene for other ailments.
Types of Renal Stone
There are various types of renal stones depending on the kind of precipitation:
Calcium oxalate stones: 80% of the kidney stone are composed of calcium oxalate crystals. Contrary to belief, current clinical evidence suggests that the consumption of low-calcium diets is actually associated with a higher overall risk for the development of kidney stones. As the amount of calcium intake decreases, the amount of oxalate available for absorption into the bloodstream increases. This oxalate is then excreted in greater amounts into the urine by the kidneys thus forming stones. Formation of these stones indicates presence of disorders like hyperparathyroidism and renal tubular acidosis
Uric acid (urate) stones: Uric acid stones are about 5–10% of all kidney stones. Uric acid stones form due to conditions like hyperuricosuria or hyperuricemia; or any acid/base metabolism disorder.
Other types of stones: Other types of kidney stones are composed of struvite (magnesium, ammonium and phosphate). Formation of struvite stones is associated with the presence of urea-splitting bacteria like Proteus mirabilis, Klebsiella, Serratia and Providencia. These organisms are capable of splitting urea into ammonia, decreasing the acidity of the urine and resulting in favorable conditions for the formation of struvite stones, resulting in urinary tract infection.
Treatment of Renal Stone
Treatment of renal stones is carried out on many fronts:
Fluids: Ample intake of fluids to “flush out” the renal stone is the most important treatment for this disease.
Diuretics: These are administered to increase urine flow, thus draining out the renal stone.
Medications: Non-steroidal anti-inflammatory drugs (NSAIDs) or narcotics like codeine are prescribed to decrease pain. Hydrocodone is prescribed to eliminate nausea and vomiting, which would have necessitated hospitalization. Besides, certain medications are used to increase the passage-rate of kidney stones out of the system like calcium channel blockers (nifedipine) and alpha blockers (tamsulosin). Alpha adrenergic blocking agents like terazosin or doxazosin; which reduce the muscle-tone of the ureter and facilitate stone passage are also prescribed.
Extracorporeal Shock Wave Lithotripsy (ESWL): This is a procedure where shock waves are used to break up a large stone into smaller pieces that can then pass through the urinary system. But this method has limitations that it causes bleeding and may fail to fragment the stone sufficiently.
Surgery: If the kidney stone does not get smaller and pass out of the system in four weeks, surgical techniques have to be employed. This is 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. Percutaneous nephrolithotomy may ultimately be necessary for large or complicated stones if non-invasive methods fail.
Ureteral stent: One technique uses a ureteral stent (placing a small tube between the bladder and the inside of the kidney) to provide immediate relief from a blocked kidney. Ureteral stents have a “double-J” or “double pigtail” shape, so-called because of the curl at both ends. They are designed to allow urine to drain around any stone or obstruction. Most stents can be removed easily during a final office visit. Stents cause minimal or moderate discomfort but are very successful.
Living with Renal Stone
If treated early, renal stone may not be life-threatening, but it does adversely affect the quality of life of the patient. The persistent spasmodic pain, pain during urination, bleeding during urination, dribbling of urine, weight loss, fever, etc can have a very debilitating effect and cause personal and professional inconvenience to the patient.
Prevention of Renal Stone
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. Some of the preventive measures are:
1) Drinking enough water to make 2 to 2.5 liters of urine per day
2) Diet low in protein, nitrogen and sodium
3) Avoiding food rich in oxalate like chocolates, nuts, soy beans, spinach
4) Intake of calcium supplements or diet rich in calcium
5) Intake of certain juices like orange, cranberry, blackcurrant, which help lower risk factor of certain specific stones
6) Avoiding large doses of vitamin C
7) Avoiding cola drinks
8) Eating vegetables and fruits with a lot of water content.
The National Institute of Health recommends drinking up to 12 full glasses of water a day, if you’ve already had a kidney stone and at least 8 full glasses of water, if you don’t. Water helps to flush away the substances that form stones in the kidneys.