Health A to Z

Highlighted Disease

Kidney Stones

Definition:

Broadly speaking, kidney stones also include stones in other parts of the urinary system, since they all arise from the kidney. Our two kidneys are situated at the back of the abdomen. Their main function is to remove waste from the body in the form of urine. Blood is filtered as it is passed through the kidneys. The fluid containing the waste is drained into a space called the renal pelvis in the centre of the kidney, which leads to a tube called the ureter to connect with the bladder and urethra.

When the concentration of a particular mineral in the urine is too high, crystals may form and grow in size, resulting in stones. A stone can be dislodged and pass along the urine stream, until finally get this caught wherever the channel is too narrow to go through. The symptoms it causes depend on the stone's size and location, and it is also the size and location that determine the way a kidney stone should be managed.

• Who is at risk?
• Symptoms
• Treatment
• Prevention

What else should I know?

Details of other alimentary disease

Source: Quality HealthCare

Who is at risk?

Stone disease is two to three times more common in males than in females. A man has about 12 % lifetime risk of developing a kidney stone. It occurs more often in the middle aged than in the elderly. Kidneys stones can happen in children, though rarely so. Kidney stones are more frequently encountered in hot, arid areas.

Decreased fluid intake and consequent urine concentration are among the most important factors influencing stone formation. Certain occupations such as drivers are more prone to the disease. Some medications, such as anti-hypertensives and diuretics, can affect the mineral contents of urine, and increase the chance of stone formation.

Oxalate, a salt present in many vegetables, is a common component in kidney stones. Some kidney stones may consist of largely uric acid, a byproduct of nucleic acids we take from the diet. Patients suffering from certain metabolic diseases that result in high blood calcium or uric acid levels are in particular risk of kidney stones.

Most kidney stones contain calcium, but the role of dietary calcium is less clear. It has been shown that calcium restriction cannot prevent stone disease, and is no longer universally recommended. Some people are born with a tendency to have higher calcium levels in their urine, and are more prone to kidney stone formation. This tendency runs in families.

Repeated urinary tract infections can also precipitate stone formation. Kidney stones can develop in cancer patients undergoing chemotherapy, as the rapid breakdown of cells produces large amount of uric acid.

Back to top

Symptoms:

The type of pain caused by stones is often called a colic-meaning that the pain comes as cramps, waxing and waning as if a woman in labour. The pain frequently begins on one side of the flank, radiating to the lower abdomen and the groin. Sometimes the site of pain migrates downwards as the stone is passed along the ureter. When the stone is approaching or is inside the bladder, the patient may feel pain and urgency in passing urine. Some patients may find with blood in their urine. This is especially common with uric acid stones.

Back to top

Treatment:

The pain caused by kidney stones is notoriously severe. The presence of pain itself is not an ominous sign though, since pain is associated with the migration of the stone. The pain can be partly relieved with analgesics or drugs which relax the smooth muscles of the urinary tract.

If a kidney stone is suspected, doctors need to confirm its presence, size, location, and its effect on the kidney functions. That's why a number of urine and blood tests as well as radiological examinations are necessary. Most, but not all, stones show up on X rays. To locate a stone more accurately, doctors would order an IVP (intravenous pyelogram or intravenous urogram, IVU) where a drug, called a contrast, is injected into the blood to let the urinary tract show up in a series of X rays films. If you have a history of severe allergic reactions, you need to tell your doctor for alternative arrangements.

Stones less than 4 mm in the ureter have more than 80% chance of being passed out spontaneously. Drinking plenty of fluids (over 3 litres a day) would help. You should also look carefully into the urine and strain it to confirm the passage of stones. If found, save them up. Your doctors may take them to the laboratory for analysis. Follow up X rays may be ordered to check for the presence of residual stones.

The less fortunate patients may have stones too large or too tightly lodged. Doctors can use strong ultrasound to break them up - a procedure called extracorporeal shock wave lithotripsy. When that fails doctors may need to remove them surgically.

Back to top

Prevention:

Doctors may collect fragments of the stone for analysis and recommend a special diet depending on the findings, taking into consideration of your dietary habits. Occasionally patients may need drugs to prevent stone formation. Approximately 50 percent of patients with kidney stones have a recurrence within 10 years.

To prevent kidney stones, you should:

1. Drink plentifully and frequently - Avoiding dehydration is important in preventing kidney stones. A glass of water should be taken with each meal, between each meal, and before sleep for maximal effect.
2. Decrease salt intake - A salty diet produces urinary conditions that promote kidney stones formation by increasing calcium content in the urine.
3. Decrease animal protein intake - Red meat is a precursor of uric acid, a constituent of some kidney stones. Foods rich in uric acid also include organ meats, game meats, anchovies, sardines, herring, mussels and scallops.
4. Decrease oxalate intake - Oxalate is another constituent of kidney stones found in certain plants and their products such as nuts, chocolate, tea, spinach, beans, dark leafy greens, soy, rhubarb, strawberries. Avoid them if you have had oxalate stones.
5. Do not take excessive vitamin C.
6. Increase your dietary fibre intake.

Back to top