What Are Kidney Stones?

Kidney stones can be caused by a high concentration of crystals in the urine. These include oxalate and urate, which can also be found in normal urine.

They do not normally cause problems when present in low levels, but can form crystals and may cause stone formation at higher concentrations.

These stones in the kidney may travel down the urinary tract and can cause pain or blood in the urine. Smaller stones may be passed out but larger stones can obstruct urinary flow, and may then require further treatment or procedures. Your doctor will advise on the appropriate treatment you require.

The common types of kidney stones are calcium oxalate or calcium phosphate. Other types of stones include struvite stones, uric acid stones and cystine stones.

What Are the Symptoms?

Symptoms of kidney stones may include:

• Severe flank pain

• Pain on urination, in the lower abdomen or groin

• Pink, red or brown urine

• Cloudy or foul-smelling urine

• Persistent urge to urinate

• Fever and chills, if infection is present

However, some kidney stones may not cause any symptoms at all.

Lifestyle Factors

The following lifestyle factors increase your risk of kidney stones:

• Inadequate fluid intake

• Excessive intake of protein and sodium

• Being obese (BMI >23)

The following dietary recommendations may reduce the risk of kidney stone formation.

Stay well hydrated

Drink 2-3L (8-12 cups) of fluid daily to ensure good urine output and prevent accumulation of minerals in the kidney.

You are recommended to take fluids with higher citric content, and to minimise intake of carbonated drinks. If weight is of concern, limit the intake of all higher calorie drinks. Examples of drinks with high citric content include:

Choose foods lower in sodium

Consume fresh food and limit your processed or preserved food intake. Examples of these types of food are:

Consume a moderate amount of protein

Limit your protein intake to 2-3 servings a day. Examples of 1 serving are:

Consume adequate calcium

Calcium from food does not increase the risk of kidney stones, and individuals should opt for calcium-rich foods instead of supplements. Do not intentionally reduce dietary calcium intake as an inadequate amount of calcium will also result in deficiency conditions such as osteoporosis.

The table below shows the recommended calcium intake for normal healthy persons:

It is recommended to have 1 serving of a high-calcium dairy product daily. Examples of 1 serving are:

Reduce foods high in oxalate

Reducing the intake of oxalate-rich foods can reduce the chance of stone formation. Examples are:

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