Leave no stone unturned

by | March 24, 2021

Many complain of the pain associated with kidney stones, which can range in size from a grain of sand to the size of a golf ball. Find out more about the symptoms and treatments.


A number of celebrities have had kidney stones, which can range in size of a grain of sand to the size of a golf ball, including actor William Shatner and singer Billy Joel. Many have described the pain associated with these stones as painful as childbirth.

Ageless Online finds out more about kidney stones with the help of Tan Tock Seng Hospital’s (TTSH) urologists – Adj A/Prof Lee Yee Mun, senior consultant, urology and Dr Yeow Yuyi, consultant, urology:


What are kidney stones in layman’s terms?

Stones in the urinary system are usually crystals formed by minerals and salts that are present within urine.


Are there different types of stones?

There are many different types of stones that differ in their composition. The most common type of kidney stones formed is calcium oxalate. Oxalate is a substance that is made daily in your liver or absorbed from your diet. Certain fruits and vegetables as well as nuts and chocolate contain high oxalate content. Dietary factors, high doses of Vitamin D, intestinal bypass surgery and several metabolic disorders can also contribute to calcium or oxalate in the urine. Other stones can be made up of substances such as uric acid, or they can be formed in the presence of urinary tract infection.

Stones can also be classified according to their location in the urinary tract. The upper urinary tract would consist of stones in the kidney or the ureter (tubes that join the kidney to the bladder), while the stones in the lower urinary tract would include stones in the bladder or the urethra.


What causes them?

Kidney stones are usually formed when the urine becomes concentrated, causing mineral deposits to group together and become crystals that form stones. It is often difficult to pinpoint a single cause for kidney stones.


What are the risk factors? Is family history also a risk factor?

There are a few risk factors for the formation of stones.

  • Family history – A close family member with a history of stones increases your risk of forming stones as well.
  • Personal history of stones – If you have had stones before, you are at higher risk of recurrence.
  • Insufficient fluid intake – A lack of water intake appropriate for activity level usually causes urine to be concentrated. This in turns increases the risk of stone formation.
  • Poor dietary habits – Diets high in salt and protein increase the risk of stone formation. This is especially true for diets that contain a lot of sodium, as it increases the amount of calcium in the urine and therefore, the risk of stone formation.
  • Intestinal disorders or surgery – Gastric bypass surgery, inflammatory bowel disease can affect calcium and water absorption, increasing the risk of stone formation.
  • Certain medications and supplements – Especially when taken excessively such as Vitamin C.


What are the symptoms?

  • Many people have no symptoms.
  • Pain at the side or lower abdomen and groin area.
  • Pain or burning sensation when urinating.
  • Blood in urine or cloudy urine.
  • Frequent need to pass urine.
  • Nausea or vomiting.
  • Fever and chills if infection is present.


Why are men more predisposed than women?

This is true previously, although the gender differences worldwide seem to be decreasing. This could be due to various factors such as:

  • Dietary differences in men, with a higher likelihood of consuming foods high in protein or oxalate.
  • Different activity levels and/or occupation, resulting in increased sweating and decreased water intake.
  • Higher prevalence of obesity in men.


What is the percentage of those who pass out kidney stones with no significant problems, compared to those who might need surgery?

This is related to the size of the stones. For stones below 4mm in size, the chance of spontaneous passage can be 80 percent or more, but for stones above 8mm, this falls to below 20 percent.

Spontaneous passage however does not mean that there are no symptoms. Sometimes, patients can still feel pain or discomfort during the passage of stones, even if they do eventually pass them out without the need for surgery.


What is the prevalence in Singapore?

It is difficult to comment on the exact prevalence as no known studies collect such information in the Singapore population. However, within Asia, the prevalence of stones is estimated at between five to 19 percent.

We have, however noticed that there are younger patients in their 30s or even younger who are being diagnosed with kidney stones. This may be related to the increasing affluence and a diet high in animal protein and salt.


How does one get diagnosed with kidney stones? Is it regular blood and urine tests?

For patients who have no symptoms, the stones are usually found incidentally during health screening. They can be picked up when they are found to have blood traces in urine, which leads to further tests that discover such stones.

Other patients can have symptoms as described previously, which lead to further tests that discover these stones.


What constitutes a small or a large kidney stone (measurement)?

For stones in the kidney, we usually would say that a stone larger than 2cm is considered a large stone that may require more invasive surgical treatment. Otherwise, most stones above 1cm in size are unlikely to pass spontaneously and would usually require some form of treatment as well.


You mentioned doctors can prescribe medication for those to pass it out easily. What medication is this? Can drinking water and pain relievers help on this too?

For medication to help stones pass, this is usually only applicable for stones within the ureter. We would prescribe certain medicines to help to relax the muscles of the ureter to help stones pass. These are usually given for up to a month to help the stones pass.

For stones within the kidney, medications to help them pass usually do not work. However, for specific stone types such as uric acid stones within the kidney, it is possible to take medications to dissolve them but this can take some time to work (weeks to months).


For those larger stones, surgery is necessary. What are the different types of surgery available and what makes them different?

There are a few types of surgical treatment that can be performed for stones in the kidney or ureter.

a) Extracorporeal Shockwave Lithotripsy (ESWL) – This is the least invasive procedure done in an outpatient setting, in the clinic. ESWL breaks stones using focused sound waves. When the stones are broken into smaller pieces, they will then pass more easily.

b) Ureteroscopy and laser lithotripsy – For relatively small stones, usually under 2cm, minimally-invasive surgery can be performed under general anaesthesia as a day procedure. This uses a small endoscope to go into the ureter or kidney and uses a laser to break the stones into smaller pieces. They can then be removed during the procedure.

c) Percutaneous Nephrolithotomy (PCNL) – For larger stones over 1.5 to 2cm in size, we perform PCNL under general anaesthesia. This involves making a small incision in the side of the body (<1cm in size) and inserting a small endoscope into the kidney to break and remove stones directly.

With recent advances in technology and technique, the instruments, and therefore incisions have become smaller, which reduces the bleeding risk during surgery and reduces the pain after surgery. This results in a shorter hospitalisation period after surgery.

PCNL was traditionally performed with patients in the prone (face-down) position, but now we can usually perform it with the patient lying supine (face-up). This can reduce the duration of surgery and is also suitable for some patients who otherwise cannot lie face-down.

PCNL in supine position also facilitates combined surgery using the percutaneous and endoscopic methods to maximise the efficiency of stone removal. This can reduce the number of procedures that a patient may need to treat complex and larger stones. Most patients who undergo PCNL can go home after one to two night’s stay in the hospital. There is also ECIRS (endoscopic combined intrarenal surgery), which is essentially combining PCNL with flexible ureterorenoscopy. It provides a two-in-one combined access from top and bottom – the flank incision and endoscopic from the urethra.


After surgery and passing of the stones, can they return? If so, how can one then prevent them (such as reducing sodium, eating calcium-rich foods, limiting animal protein and avoiding stone-forming foods like beets, etc)?

Yes, as mentioned above, a person with previous stones is at higher risk of future stone formation. Preventive measures would aim to reduce the risk factors mentioned above, such as increasing water intake, and reducing the intake of sodium and salt in the diet.

A common mistake is to reduce calcium in the diet after having had a calcium stone. In fact, a previous study showed that people who reduced calcium in their diet had a higher risk of stone formation compared to those who took a normal amount of calcium in their diet.


For those who had kidney stones, do they have to take medications after surgery/when it naturally passes out?

After kidney stone surgery, some medications may be prescribed for a few reasons.

  • Painkillers in the early period after surgery.
  • Medications to help stone passage, particularly if ESWL (shockwave lithotripsy) was performed, as the fragments are passed out naturally by the body.
  • Antibiotics if there is a significant risk of urinary tract infection.

Some medications may also be prescribed later to lower the risk of stone formation, after specialised tests have been performed to evaluate urine composition in terms of minerals and salts.


Anything else to add?

Although passing of kidney stones can be painful, the treatments do not have to be! With improvements and miniaturisation of surgical instruments, stone surgery can be safely carried out with minimal hospital stay and minimal post-operative pain.



(** PHOTO CREDIT: Unsplash/Rad Cyrus)


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