Kidney Stones

Kidney Stone Formation is a Treatable Condition

Aug 21, 2009 Kimberly Buck

One of the most common diseases of the urinary system is the formation of kidney stones.

Kidney stones, also known as renal calculi, occur when magnesium, uric acid salts, or calcium aren't properly processed by the kidneys. The kidneys form small crystallized stones with sharp edges that can stay in the renal pelvis without causing pain. Although most renal calculi are smaller than 5mm in diameter, some can accumulate to be much larger and cause severe pain and damage to both the kidney and the ureter. When the stone moves from the renal pelvis to the renal sinus, it is expelled via peristalsis down the ureter. The bladder releases the stone with stored urine.

Kidney Stone Size and Pain

When kidney stones reach a certain size, its movement into the renal sinus can cause tears in the calyxes and in the ureter. Stones can get lodged and block the flow of urine, causing pain and creating a backup of urine in the kidney and ureter. Renal calculi can form in one or both kidneys.

Pain in the flank of the affected side is usually the first symptom of kidney stones. Some patients describe the pain as a stabbing feeling that won't go away. In fact, women who have had both kidney stones and give birth say that having kidney stones in much more painful.

A nephrologist or urologist will ultrasound the kidneys to confirm the presence of calculi and do a urinalysis to see if erythrocytes are present in urine.

Erythrocytes in urine can signal the presence of a stone that is moving inside the kidney or down the ureter. Some calculi are too small to see even in an ultrasound. The stones that cause the most pain are often seen into the renal sinus of the kidney or are passing through the ureter.

In most cases, kidney stones can be left untreated and pass on their own. Some can even remain in the kidney for years without causing any symptoms. Larger stones that are left untreated can cause urine blockage if they become lodged in the renal sinus or ureter.

Reasons for Kidney Stone Formation

There are several possible causes of renal calculi formation. About 50% of kidney stone sufferers excrete an excessive amount of calcium in their urine, usually an output of more than 300 mg in men or 250 mg in women. This condition is called hypercalciuria. Other conditions that can predispose a person to renal calculi formation are frequent urinary tract infections, high levels of calcium in the blood, and alkaline urine.

Another common cause of renal calculi formation is low urinary volume. Calculi can form into stones if an individual is dehydrated for an extended period of time. Even mild dehydration that isn't noticeable to most people can cause renal calculi formation in those who are prone to it.

People who form stones are advised to drink enough water to urinate 2 L of urine or more on a daily basis. Alkaline urine can cause the formation of uric acid stones.

Hyperoxaluria is the most common cause of kidney stones formation. This occurs when oxalate, an end product of metabolism, forms into a complex with calcium. Excessive calcium oxalate secretion can be caused by certain enzyme deficiencies, high consumption to vitamin C, and a diet rich in high oxalate food

Kidney Stone Treatment

The most common treatment for kidney stone removal is lithotripsy. Sound waves are sent through the kidney to break up the calcified stones. The fragments, usually broken down to the size of grains of sand, can easily pass through the ureter into the urinary bladder and out of the body via the urethra. Some larger fragments can try to pass through the ureter and still get stopped despite lithotripsy. When this happens, a nephrologist or urologist goes inside the ureter through the bladder to scoop out the stones manually. The surgeon then places a stint, or small thin tube, inside the ureter to allow it to heal without collapsing or becoming inflamed. The stint can be removed within a few days to a week.

Kidney stones sufferers are advised to drink a lot of fluids, especially water. Frequent filtration of fluid through the kidney doesn't allow time for stones to accumulate. People with kidney stones are also advised to avoid food that contains oxalate like nuts, rhubarb, spinach, chocolate, cola, and berries. The consumption of calcium doesn't seem to have an effect on the formation of kidney stones. Unfortunately even with these measures people who form kidney stones are prone to have a second episode. Kidney stone sufferers are also advised to keep their weight down and include regular exercise.

Sources:

Stedman's Concise Medical Dictionary. 5th ed. Philadelphia, PA: Lippincott Williams & Wilkins, 2004.

Greenberg, Arthur, ed. Primer on Kidney Diseases. 3rd ed. New York: Academic P, 2001.

Marieb, Elaine, and Katja Hoehn. Human Anatomy and Physiology. 7th ed. Boston, MA: Benjamin-Cummings Company, 2007.

Thomas, Nicola, ed. Renal Nursing. 2nd ed. London: Bailliere Tindall, 2002.

"Kidney Stones in Adults" WebMD. 2008. Webmd.com. 1 Dec. 2008

The copyright of the article Kidney Stones in General Medicine is owned by Kimberly Buck. Permission to republish Kidney Stones in print or online must be granted by the author in writing.

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