Renal calculi, features, prevention, treatment

What are renal calculi?

Renal calculi (kidney stones) are chemical crystals that form into a hard salt solid structure that looks like and feels like a common stone we find on the streets. They vary in size, shape, and consistency, according to their chemical composition. They could be calcium oxalate stone, cystine stone, uric acid stone, infection stone, or even a combination.

Where do these stones come from?

Our two bean-shaped kidneys are important blood filters which eliminate chemical waste from our body and excreted into the urine. Without our kidneys, the build up of chemical waste in our body could reach a poisonous, even deadly, level within a few days. In people who have a high risk of forming stones, these chemical crystals solidify in the kidney calices (cup-shaped areas of the kidney). Some of these stones could travel down the ureter (a small muscular tube the connects each kidney to the bladder), causing severe colicky pains from ureteral irritation and spasm.

How large are these stones?

Renal stones vary in sizes, from the size of a grain of sand to as large as a golf ball. Many small stones (silent stones) are passed naturally. Medium stones are often crushed with ESWL (Extracorporeal Shock Wave Lithotripsy), popularly known as Lithotripsy for short. Large stones may need Percutaneous Lithotripsy. Very large stones may need surgical removal, especially the staghorn calculus, which “staghorn” shape and large size lodge it in the kidney pelvis (main chamber) and prevent it from entering and passing down the small ureter. Some stones have round, smooth, surface, and could pass down the ureter to the bladder with lesser pains. Others have sharp, jagged edges, causing more pains when they travel down, or get caught, in the ureter.

What increases the risk for stones ?

Not drinking enough fluids, dehydration, eating certain foods, urinary tract infection, living in hot climate, and family history of kidney stones are the more common factors that increase the risk of kidney stone formation. Metabolic or endocrine problems are rarer causes.

How much water should one drink a day?

In a normal average daily situation, it is advisable to drink about 8 glasses of fluids (water, juices, preferably not pop) a day, whether one had kidney stones before or not. Those who had kidney stones in the past are advised against cola drinks, tea, chocolate, spinach, and peanut, which are high in oxalate, and dairy products which are high in calcium. Those with cystine stones are advised against eating foods high in Methionine, like fish.

Is renal colic really more painful than childbirth?

Yes, women who had kidney stone colics and had given birth say so. The pain is most excruciating, and in men, it could radiate down to the lower abdomen and to the scrotum of the affected side where the stone is. One thrashes around to find a more comfortable position, only to find none. Narcotic shots are given for the relief of the severe renal colic. Sometimes, renal colic could mimic, or be confused with, acute appendicitis. In some patients, there could be blood in the urine, from the irritation of the ureter where the stone is lodged.

What are the diagnostic tests for kidney stones?

After a thorough history-taking and physical examination, your physician may order urinalysis, urine culture (for bacteria), blood count, blood chemistry (including calcium, phosphorus, BUN, creatinine, uric acid, and electrolytes) a KUB (plain x-ray of kidney, ureter, bladder), an IVP (intravenous pyelogram, x-ray with dye to see locate the stone), an Ultrasound (a “3-Dimensional” picture of the kidney); and/or a CT Scan (Computed Tomography, an X-ray technique showing cross-sectional images of the abdominal area to locate and identify the stone). Twenty four-hour urine sample may also be taken to find out the levels of stone-related chemicals in the urine. Provocative Tests may also be done to see how the kidneys handle chemicals. Stone analysis is essential to determine the chemical composition of the stone, which will help identify the cause of the stone formation and aid in the preventive treatment in the future.

Are some stones dissolved by medications?

Yes, bicarbonate/potassium citrate may dissolve uric acid stones and cystine stones. This is why it is important strain the urine when one suspects kidney stones, to find out what the chemical composition of the stone is. Medications prescribed to dissolve kidney stones are taken for a lifetime. Unfortunately, not all stones are dissolved by medications. However, many kidney stones are passed naturally. Sometimes alpha blocker drug is used to relax the muscles of the ureter to allow passage of larger stones. Newer extracts to dissolve all types of kidney stones (and gallstones also) are being researched in laboratories around the world.

How does one prevent renal stones?

Uric Acid stones are found among those who overproduce uric acid (gout), and can be worsened by a high-meat diet (high in purines), especially pork and beef. Allupurinol is one drug that reduces uric acid. Cystine stones come from too much cystine (amino acids) in the body, caused by an inherited condition. Penicillamine or Tiopronin reduces cystine. Prevention in this case includes diet low in methionine (a normal chemical found in fish). Infection stones, as the name suggests, is caused by a rinary tract infection. Antibiotics are given before the stones are removed. In all these three conditions, drinking lots of water helps a lot in preventing recurrent kidney stones. Popular old-fashioned lemonade is effective in reducing kidney stone formation.

What is ESWL?

If the stone or stones cannot be dissolved by medications or are too large to pass down the ureter, Extracorporeal Shock Wave Lithotripsy is an option. There are several types of ESWL but the principle is the same for all. The patient lie down or sits up in a water bath, high-energy shock waves from the high-tech machine are precisely aimed at the stone (with pin-point accuracy). The waves, passing through the water cushion, travel at a high speed, pass through the soft tissues of the body without harming them and “shatter” the stone (only) into very fine sand. The procedure is done with mild sedation, and may last about an hour and done as an outpatient or on an overnight stay.

What is the surgical treatment?

If all of the above therapies fail, invasive or surgical approach is the final option. This includes fishing out the stone in the ureter with a Ureteroscope. Percutaneous Lithotripsy is used for stones larger than one inch in diameter and where ESWL did not work. A small skin incision is made in the affected flank and the stone is shattered by painless ultrasound, or removed by Percutaneous nephrolithotomy. With the available modern technology today, open surgery is now reserved only for those with very large or oddly located kidney stones.

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