What is Nephrolithiasis (Kidney Stones; Renal Calculi; Urinary Stones)

Nephrolithiasis (kidney stones) is a disease affecting the urinary tract. Kidney stones are small deposits that build up in the kidneys, made of calcium, phosphate and other components of foods. They are a common cause of blood in urine.

Statistics on Nephrolithiasis (Kidney Stones; Renal Calculi; Urinary Stones)

Kidney stones are common. About 5% of women and 10% of men will have at least one episode by age 70. Kidney stones affect about 2 out of every 1,000 people. Recurrence is common, and the risk of recurrence is greater if two or more episodes of kidney stones occur. Kidney stones are common in premature infants.

Risk Factors for Nephrolithiasis (Kidney Stones; Renal Calculi; Urinary Stones)

Some types of stones tend to run in families. Some types may be associated with other conditions such as bowel disease, ileal bypass for obesity, or renal tubule defects. A personal or family history of stones is associated with increased risk of stone formation. Other risk factors include renal tubular acidosis and resultant nephrocalcinosis.

Progression of Nephrolithiasis (Kidney Stones; Renal Calculi; Urinary Stones)

Kidney stone formation may result when the urine becomes overly concentrated with certain substances. These substances in the urine may complex to form small crystals and subsequently stones.

Stones may not produce symptoms until they begin to move down the ureter, causing pain. The pain is severe and often starts in the flank region and moves down to the groin. The size of the renal stone will dictate the natural history of this condition.

If the stone is less the 5mm in diameter, then it will most likely pass on future urination. If the stone is larger than 5mm, urological procedures may be required to remove the stone. Surgical intervention will be required in any patient whose urinary tract in completely obstructed. This situations represents a surgical emergency.

Symptoms of Nephrolithiasis (Kidney Stones; Renal Calculi; Urinary Stones)

Symptoms of renal stone disease may include:

How is Nephrolithiasis (Kidney Stones; Renal Calculi; Urinary Stones) Diagnosed?

A number of blood and urine tests will be required to detect the presence of infection and test the function of the kidneys. Urinary tests may also allow the type of stone to be identified, allowing further guidance of therapy.

When urinary stones are suspected, a x-ray of the abdomen is also required to detect the stones or any other problem causing a similar set of symptoms.

Prognosis of Nephrolithiasis (Kidney Stones; Renal Calculi; Urinary Stones)

Kidney stones are painful but usually are excreted without causing permanent damage. They tend to recur, especially if the underlying cause is not found and treated.

How is Nephrolithiasis (Kidney Stones; Renal Calculi; Urinary Stones) Treated?

Treatment goals include relief of symptoms and prevention of further symptoms. Treatment varies depending on the type of stone and the severity of symptoms and/or complications. Hospitalization may be required if symptoms are severe.

Stones are usually passed in the urine, given enough time to flush through the system. The urine should be strained at the time of passing and the stone saved for analysis of the type of stone. Fluids should be adequate to produce a large amount of urine. Water is encouraged, at least 6 to 8 glasses per day. If oral intake is inadequate, intravenous fluids may be required.

Pain-killers may be needed to control renal colic (pain associated with the passage of stones). Severe pain may require strong pain-killers such as morphine or pethidine.

Depending on the type of stone, medications may be given to reduce further stone formation and/or dissolve the material forming the stone. These may include such medications as diuretics, phosphate solutions, allopurinol (for uric acid stones), antibiotics (for struvite stones), and medications that make the urine alkaline such as sodium bicarbonate or sodium citrate.

If the stone does not pass by itself, surgical removal of the stone may be required. Lithotripsy may be an alternative to surgery. In this procedure, ultrasonic sound waves or shock waves are used to break up stones so that they may be expelled in the urine (extracorporeal shock-wave lithotripsy) or removed with an endoscope that is inserted into the kidney in surgery (percutaneous nephrolithotomy).

With resolution of the condition, the patient may be required to avoid certain food types which may increase the likelihood of developing kidney stones.

Nephrolithiasis (Kidney Stones; Renal Calculi; Urinary Stones) References

  1. Braunwald, Fauci, Kasper, Hauser, Longo, Jameson. Harrison’s Principles of Internal Medicine. 15th Edition. McGraw-Hill. 2001.
  2. Cotran, Kumar, Collins 6th edition. Robbins Pathologic Basis of Disease. WB Saunders Company. 1999.
  3. Kumar P, Clark M. CLINICAL MEDICINE. WB Saunders.
  4. Longmore M, Wilkinson I, Torok E. OXFORD HANDBOOK OF CLINICAL MEDICINE. Oxford University Press. 2001.

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