Kidney stones (renal calculi)

The urinary system, which consists of several organs including the kidneys and bladder, plays a key role in eliminating waste from the blood in the form of urine. Some of the waste comes from the foods that are eaten as they are broken down into various chemical components. Stones are small masses found in urine that develop when these chemical components stick together.

Some stones are very small and are easily eliminated. Larger stones however, can cause a great deal of pain as they travel from the kidneys to the bladder, or if they block the flow of urine. The pain can last from a few minutes to a few hours, with periods of relief. The pain is usually centered in the low back or lower abdomen, and may move to the groin.

Kidney stones may also cause the following signs and symptoms:

• Blood in the urine
• Nausea and vomiting

Causes and triggers

Kidney stones are quite common in adults, especially in men. The following factors may contribute to their formation:

• Certain dietary habits (e.g., diet high in sugar or salt)
• Certain medications and vitamin supplements
• Not drinking enough fluids
• Certain diseases or health conditions (e.g., diabetes, gout, obesity, hypertension or recurrent urinary tract infections)

Kidney stones can also develop when none of these factors are present. In fact, some individuals are naturally prone to kidney stones due to their family history. Sometimes, no cause can be found.

Treatment

Most small stones are eliminated in the urine within a few hours or days, and do not require any medical intervention. However, since this process can cause severe pain, your healthcare provider may recommend the use of pain medication. Increasing your water intake may also help eliminate the stone.

Larger stones can sometimes get stuck in the duct that connects the kidneys to the bladder. This can produce excruciating pain that often requires hospitalization. Depending on the size of the stones, they may have to be surgically removed, or broken up using a non-surgical technique that uses shockwaves.

When a stone can be retrieved (e.g., if passed at home in the urine or surgically removed), it is important to have it sent to a laboratory for analysis to determine its chemical composition.

Here are other preventive measures:

• If your health allows, increase your fluid intake to dilute the urine and increase urine volume.
• Adjust your diet based on the chemical components identified in the stone during the laboratory analysis. See a nutritionist if necessary.
• Limit your cola intake since these beverages can make urine more acidic, thereby promoting the formation of kidney stones.
• Speak to a health care professional before starting any new supplement (e.g., calcium).

When should I see a medical professional?

• If you have difficulty managing your pain with medication
• If you have fever or chills
• If you have a frequent urge to urinate or burning during urination
• If you experience severe vomiting

For more information:

• The Kidney Foundation of Canada