Words Hannah May-Lee Wong

Having stones in any part of your body may sound frightening, and that’s because it is. A large stone in the urinary tract can cause an obstruction, severe infection and, if not properly treated, can lead to the complete loss of a kidney.

Urologist Dr Hemanth Kumar Ramasamy keeps a collection of stones of different shapes and sizes in clear glass jars in his office. He has seen and treated many cases is his practice. This, he explains, is because Malaysia is located within the “stone belt” – a geographical area in the world where incidence of kidney stones is especially high.

“The stone belt extends from Afghanistan and goes through Pakistan, India, Thailand, Burma, Malaysia and so on,” says Dr Hemanth. The phenomenon is likely caused by a combination of hot weather and dietary factors such as a high sodium diet and inadequate fluid intake. “Stones can happen to both men and women. Men who have big prostates and who have not been treated may have a higher risk of developing stones. This is due to the presence of stagnant urine which promotes stone formation.”

“Urologists in Malaysia have postulated that one in 10 Malaysians will develop stones at least once in their lifetime. Do remember, most stones are so small they can be passed out on their own without causing any symptoms,” Dr Hemanth explains.

“The ureter is about 2mm wide, but since it’s a muscle, it can dilate. Any stone less than 3mm will be passed out naturally. It may hurt a little as they come out, but if you have small (1mm) stones, you generally won’t feel anything. After a certain size threshold (more than 7mm), chances of the stone being passed out spontaneously comes down tremendously.”

What are urinary tract stones?

Urinary tract stones are stones that can form in any part of the urinary tract (which include kidney, ureter and bladder stones). The upper tract is made up of the calyces (located in the kidneys), the collecting system called the renal pelvis and the ureter. The lower tract includes the bladder and the urethra.

Stones most commonly form within the kidney. After they form, the small stones fall further down the urinary tract where they can get stuck and cause severe pain. Stones can also form in the bladder, and when they do, the patient is likely to get recurrent infections.

Stones rarely form in the ureters on their own. But if a person happens to have one that is stuck in that area, the stone may grow in size; sometimes, big enough that it completely blocks the passage of urine.

How do stones from? What are they made of?

There are five major types of stones: calcium oxalate, uric acid, calcium phosphate, struvite and cysteine stones. The most common types of stones are calcium oxalate stones, followed by stones which are made up of uric acid (a by-product of purines found in red meat). The less common stones are composed of calcium phosphate – these are extremely hard stones and account for less than 10% of urinary tract stones.

Struvites are infective stones – doctors see them in patients who have regular infections and diabetes. Cysteine stones occur in people who are born with an error of metabolism. These people produce too much cysteine which is released into the urine where crystals form together.

The process of stone formation

The first step of stone formation is nucleation. This happens when ions (for example, calcium and oxalate ions) spontaneously join together to form a crystal. All stones start from a small crystal. Next, crystals that have already been formed tend to stick together. They continue to grow and propagate, forming aggregates called stones. Normally, the process is facilitated by some promoting factors or inhibitory factors.

Promoting factors include:

• Not drinking enough water
• Living in a high temperature environment (such as Malaysia)
• Having a high salt diet
• Having a diet which is high in oxalate (found in soy based products, dark chocolates, nuts) or high in purines (found in animal meat)

All these factors cause excessive water conservation in the kidneys and cause urine to be more concentrated, a driving force for stones to form. Furthermore, when a person is dehydrated, the transit time of urine is very slow. This gives crystals more time to form and grow.

“Adequate fluid intake is key,” Dr Hemanth reiterates. “When a person stays hydrated and urine is dilute, even if he eats high amounts of red meats and oxalate products, the stone forming ions will pass out easily simply because they don’t have time to form crystals.”

Inhibitory factors:

Citrate is an inhibitor of stone formation. It binds to stone forming ions such as calcium and prevents crystals from forming.

Are there any genetic causes?

Stones caused by genetic disorders may occur, but they are rare. Some people are born with physical problems of the kidneys such as having narrow tubes that can enhance stone formation. Other genetically linked disorders may cause a person to produce too much oxalate (hyperoxaluria) or produce excessive amounts of cysteine, but again, these cases are very rare.

Are stones more common in men or women? Can children get them too?

Urinary tract stones can develop in men and women, but they are much more common in men. For every three or four men, there’s only one woman who will develop stones. This may be largely due to the fact that men are generally more involved in work where the outdoor environment and lack of fluids play a role (for eg, drivers, construction workers, etc). Women generally are protected by female hormones (such as oestrogen and progesterone) which help dilate the tubes so that stones are more likely to pass out on their own.

Children can get them too, but it is less common. The ureters in children are very supple, which means even the bigger stones can pass out without symptoms. However, if children do develop stones, most times it’s because of some anomalies in their urinary tract, caused by genetically linked disorders. Kidney stones seen in children are very treatable and doctors treat them in a similar manner as they do adults.

What are the symptoms?

The stones on their own do not cause symptoms, it’s what they do to the surrounding organs. A stone starts off in the kidney. If it is small and remains in the kidney, there won’t be any symptoms. But if the stone detaches from the kidney and falls down the urinary tract, that’s when it causes trouble. It could get stuck, thereby causing an obstruction. This would cause an increase in pressure which leads to severe pain (it could be as painful as giving birth to a child!).

Having stones can also lead to infection of the kidney (pyelonephritis). It causes an inflammation in the kidney, which is very painful. A bladder infection can also occur, with common symptoms such as obstruction, severe pain, difficulty passing urine and fever.

Stones may cause haematuria or blood in the urine. On the other hand, some people have no symptoms at all. They might undergo a regular check-up only to incidentally find a stone.

How would a doctor detect stones?

Doctors use modern techniques such as ultrasound, which can also point out obstructions. CT scans are an even better option. Dr Hemanth says, “It only takes 10 seconds and the CT scan takes multiple slices of images to get the full picture. In these pictures, there is a 99% chance of detecting even 1mm stones. Through the scan, we can see where the stone is, whether it has dropped down and whether it is causing an obstruction.”

How are urinary tract stones treated?

>> Increasing fluid intake

“If you have a small stone which has not dropped (sitting in the kidney), and the size is about 1-2mm, we would advise patients to drink lots of water,” Dr Hemanth shares. If patients have high uric acid levels, the doctor can give them medicine to lower the levels. Most stones will pass out on their own.

>> Extracorporeal shock wave lithotripsy (ESWL)

For stones that are slightly bigger, and if it’s not yet an emergency (the stone has not dropped from the kidney), doctors can do an extracorporeal shock wave lithotripsy (ESWL). It is a non-invasive method where shock waves are used to blast the stone, breaking it into tiny pieces so that they can pass out naturally through the urine.

>> Scopes

For bigger stones, endoscopic procedures are the mainstay of treatment. For ureteric stones, doctors will usually perform a ureteroscopy with a semi rigid scope. If there are stones in the bladder, a cystoscopy will be carried out. If stones are in the kidney, doctors will do a flexible ureteroscopy. “Using these very tiny scopes, we go up to the stone and use a laser through these scopes to blast the stones into dust. We evacuate the pieces by flushing them out or plucking them with titanium-based baskets,” Dr Hemanth explains.

>> Percutaneous nephrolithotomy (PCNL)

When there are very big stones in the kidneys, doctors may opt for a PCNL procedure. “We make a puncture (of not more than 8mm) through the back of the patient and insert a scope. We then break the stones using a laser or an ultrasonic breaker. The stone fragments are then removed with a tiny basket,” Dr Hemanth says.

What happens if a person does not seek treatment?

The consequences could be severe. If the stones aren’t passed out, they are likely to grow bigger. Big stones cause infections, blockage, renal impairment and these could lead to the complete destruction of the kidneys. An infection causing an abscess if not treated may also lead to the removal of the kidneys.

How fast do stones grow?

The growth rate of stones is variable. They can grow very fast or the process may be very gradual. The fast ones can take only 3-4 months to grow big enough to cause problems, but the non-infective slow stones can take years. It really depends on how the patient is eating and how much he is drinking.

What can we do to prevent urinary tract stones?

It all comes down to drinking lots of water. Cut down on red meats which are high in purines, and soy based products which are high in oxalates. Consuming citrus-based fruits helps prevent stones because they contain citrate, a stone inhibitor.

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