The patient educational material on this website does not provide all available information about this condition and is not intended as a substitute for seeking professional medical care and advice. If you have any further questions or concerns after reading the information, please discuss them with your doctor.

Kidney Stones

What is a Kidney Stone?
A kidney stone is a hard mass of crystals (rock-like solid material) that forms in the kidney. A key function of the kidneys is to filter and separate substances (chemicals) from the blood, which are then excreted as waste in the urine. If, however, certain chemical substances build up in the kidney, a stone is formed.

When there are more chemical substances than can be dissolved in the urine, the crystals settle out and form stones. A stone may stay in the kidney or break loose and travel down the urinary tract. A small stone may easily pass out of the body system without causing too much pain. However, a larger stone may get stuck in lower regions of the kidneys leading to blockage of the urine flow and bringing about excruciating pain. Most kidney stones pass out of the body but those which do not may even get larger and spikier. The size of the kidney stones can vary from being as tiny as a grain of sand, or as large as a golf ball.

Normally, urine contains also other chemicals that prevent these crystals from forming. These inhibitors may not be present at the right concentration and in many cases stone formers have an insufficient level of them. Additionally to that, urine also contains promoters, which initiate and promote the formation of kidney stones. Thus, it is sometimes a balance of these inhibitors and promoters that off set and cause the formation of a kidney stone.

What types of kidney stones are there?
There are four major types of kidney stones. They are classified according to the composition of the stone (adapted from National Institute of Diabetes and Digestive and Kidney Diseases site).

Calcium stones – are the most commonly formed type of kidney stone. Calcium is part of a healthy diet. Calcium that is not used by the bones and muscles, exits out as waste product to the kidneys. In most people, the kidneys flush out the extra calcium with the rest of the urine. People who have calcium stones keep the calcium in their kidneys. The calcium that stays behind joins with other waste products to form a stone.
(Please note: Do not attempt to limit your intake of calcium without first consulting your doctor. It may be harmful.)

Uric acid stones – form when too much uric acid is present in the urine.

Cystine stones – are rare. Cystine is one of the protein building blocks that make up muscles, nerves, and other parts of the body. Cystine can build up in the urine to form a stone. The disease that causes cystine stones runs in families.

Struvite stones – can form in people who have had a urinary tract infection.
A stone may form after an infection in the urinary system. These stones are not common. They are composed of mineral magnesium and the waste product, ammonia.

In many cases, the stones contain more than one type of stone, such as a combination of calcium oxalate and uric acid.

What causes kidney stones?
The chemical substances (crystals) form a kidney stone only when there are enough of them in the urine and the right conditions are present. Your chances of forming kidney stones are largely determined by your genetic makeup and by the way your diet and lifestyle interplay with this genetic inheritance. It is also possible to form stones even if it is not a part of your family history, although some forms of stone disease have a genetic basis (i.e. runs in the family). Others show a strong dependence on environmental, nutritional factors or medical condition(s) for their origin. Kidney stones strike most typically between the ages 20 and 40. Once a person gets more than one stone, others are likely to develop.

What are the signs and symptoms of kidney stones?
The size, shape, and location of the stone can cause many different symptoms. Many stones can cause the following:

• Bloody urine
• Cloudy or foul smelling urine
• Extreme pain in your back that will not go away (constant soreness and tenderness)
• Fever and chills
• Frequent burning sensation during urination
• Infection
• Nausea and vomiting
• Sudden severe pain (sharp instant pain), or
• Urinary flow obstruction

How are kidney stones diagnosed?
Sometimes “silent” stones – those that do not cause symptoms are found on x-rays taken during a general health exam (checkup). These stones would likely to pass unnoticed.

More often, kidney stones are found on a special x-ray (called IVP- intravenous pyelogram) or sonogram (ultrasound scan) taken on someone who complains of blood in the urine or sudden pain. These diagnostic images give the doctor valuable information about the stone’s size and location. On the other, your doctor may order laboratory tests, including urine and blood tests to help detect any abnormal substances that might promote stone formation. You may be asked to collect your urine for 24 hours after a stone has passed or been removed. The sample is used to measure urine volume and levels of acidity (i.e. pH), calcium, sodium, uric acid, oxalate, citrate, and creatinine (a product of muscle metabolism) or creatinine (the level of this substance assist in determining the kidney function). The information will be used to determine the cause of the stone. A second 24-hour urine collection may be needed to determine whether the prescribed treatment is working.

The type of kidney that a person suffers from can also be identified from the stone itself. If a stone has been removed, or if you’ve passed a stone and saved it, the laboratory can analyse it to determine its composition.

Your doctor may ask about your medical history, occupation, and eating habits. This will assist in determining the cause of the kidney stone and any trigger factors.

What is the prognosis?
If you’ve had more than one kidney stone, you are likely to form another, so prevention is very important.

What are the treatment/prevention options?
Treatments options include instrumental, ultrasound, surgical procedures, and/or medications, depending on the type of stone, size and location. However, most kidney stones pass out of the body without any medical intervention by a physician.

Talk to your doctor about how to avoid more stones from forming. There may be a special diet that you may need to adhere to. Your doctor will be able to recommend you which foods you need to cut back. Drinking lots of water will also help reduce stone formation, by flushing out these chemical substances from the kidneys.

Please consult your doctor if you have any questions about your health, your condition or your medication. Remember, your doctor is the best source of information regarding you and your health.

Where can I find more information about this condition?
Additional information is available from the following website(s):

http://www.kidney.org.au/renal_resources/fact_sheets/focus_kidney_stones.asp
http://www.betterhealth.vic.gov.au/bhcv2/bhcpdf.nsf/ByPDF/Kidney_stones/$File/Kidney_stones.PDF
http://www.niddk.nih.gov/health/kidney/pubs/whastone/whastone.htm

http://www.urocit-k.com