Kidney stone: Causes and treatment

 16 Mar 2016 - 12:35

Kidney stone: Causes and treatment

 

By Dr Raju Abraham 

In most cases, there is no known reason why a stone forms in kidney. Most stones are made of calcium. However, in most cases, the amount of calcium and other chemicals in the urine and blood is normal. You are more likely to form a stone if your urine is concentrated. For example, if you exercise vigorously, if you live in a hot climate or if you work in a hot environment when you may lose more fluid as sweat and less as urine.

Underlying causes are uncommon
In a small number of cases, a medical condition is the cause. Various uncommon conditions can lead to high levels of chemicals in the body, such as calcium, oxalate, uric acid and cystine. If the level of these chemicals is high enough in the urine, they can form into stones.

Medicines
Taking certain medicines can make you more prone to making kidney stones. Examples include diuretics (water tablets), some chemotherapy medicines for cancer and some medicines used to treat HIV. However, many people safely take these medicines without developing kidney stones.
You are also more prone to develop kidney stones if you have:
• Recurrent urine or kidney infections.
• A kidney with scars or cysts on it.
• A close relative who has had a kidney stone.

Any tests needed
Tests to confirm the presence of a kidney stone: If you have symptoms that suggest a kidney stone, special X-rays or scans of the kidneys and ureters may be done. These tests aim to detect a stone and to check that a stone is not blocking the flow of urine.
Tests to rule out or confirm an underlying cause: Kidney stones are common and in most cases they are not caused by a known underlying disease. However, some routine tests may be recommended to rule out underlying problems. In particular, tests are more likely to be advised if you have recurring kidney stones, have symptoms of an underlying condition, have a family history of a particular condition or if a stone forms in a child or young person.
Tests include:
• A blood test to check that the kidneys are working properly.
• Blood tests to check the level of certain chemicals such as calcium and uric acid.
• Urine tests to check for infection and for certain crystals.
• An analysis of the stone if you pass it out. To catch a stone, pass urine through gauze, a tea strainer or a filter such as a coffee filter.
If the pain eases with pain relief and you do not have symptoms to suggest complications (most people), then your doctor may arrange any tests to be done as an outpatient. However, some people are admitted to hospital for strong painkillers and tests.

Possible complications
Complications from kidney stones are uncommon (although the pain at the time can be severe). Sometimes a large stone can completely block the passage of urine down one ureter. This may lead to infection or damage to the kidney. This is usually avoided, as X-rays or scans will detect a blockage and large stones can be removed.

Treatment for kidney stones
The common situations: Most stones that cause renal colic are small and pass out with the urine in a day or so. You should drink plenty of fluids to encourage a good flow of urine. Strong painkillers are often needed to ease the pain until you pass the stone. No other treatment is usually needed.
Some stones that form and stick in the kidney do not cause symptoms or any harm. They can just be left if they are small. Sometimes you may be offered medicines to help the stone pass through, such as nifedipine or tamsulosin.
Some stones become stuck in a ureter or kidney and cause persistent symptoms or problems. In these cases, the pain usually becomes severe and you may need to be admitted to hospital. There are various treatment options which include the following:
• Extracorporeal shock wave lithotripsy (ESWL). This uses high-energy shock waves which are focused on to the stones from a machine outside the body to break up stones. You then pass out the tiny broken fragments when you pass urine.
• Percutaneous nephrolithotomy (PCNL) is used for stones not suitable for ESWL. A nephroscope (a thin telescope-like instrument) is passed through the skin and into the kidney. The stone is broken up and the fragments of stone are removed via the nephroscope. This procedure is usually done under general anaesthetic.
• Ureteroscopy is another treatment that may be used. In this procedure, a thin telescope is passed up into the ureter via the urethra and bladder. Once the stone is seen, a laser (or other form of energy) is used to break up the stone. This technique is suitable for most types of stones.
• Stone removal can be done by a traditional operation where the skin has to be cut to allow access to the ureter and kidney. This is only needed in a very small number of cases where the above, newer techniques have not worked or are not possible. It may be done if you have a very large stone in your kidney.
Another option for a stone made purely from uric acid (about 1 in 20 stones) is to dissolve the stone. This can be done by drinking plenty of fluids and making the urine alkaline with medication.

How to prevent
About half of people who have a kidney stone develop another one within 10 years. Sometimes stones can be prevented from forming.

Dr Raju Abraham MBBS, MS, Mch is a Urology Specialist at Aster Medical Centre, Al Hilal, Doha.

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