SINGAPORE : Taxi driver Lee Thian Sze was caught unawares when his doctor found a fist-sized stone in his right kidney two years ago.

Despite the sheer size of the stone — it measured about 59mm in diameter — the 56-year-old did not experience any symptoms typically associated with kidney stones. An annual health checkup had picked up the problem when microscopic traces of blood were found in his urine.

The condition is commonly accompanied by painful signs such as back and groin pain, or blood in the urine. However, some “silent stones” — as in Mr Lee’s case — are not accompanied by symptoms. The latter can be dangerous in the long run.

Dr Lee Yee Mun, a consultant at Tan Tock Seng Hospital’s department of urology, said patients who experience symptoms are “often compelled to seek medical attention early”.

“However, there are patients with large stones but have no symptoms and, as a result, seek treatment very late.”

Said Mr Lee, who has since had the stone surgically removed: “If I had felt any pain, there would be no chance for the stone to grow so big because I would have taken it out a long time ago.”

Kidney stones, particularly those obstructing to the flow of urine from the kidneys, can result in kidney damage.

“If left untreated for a long time, renal failure ensues. This is largely irreversible. Even after eradication of the stone, kidney function does not return to normal again,” said Dr Lee.

Kidney stones are formed from waste products in the urine.

According to Dr Lee, up to 15 per cent of the population will develop at least one kidney stone in the course of their lives, with a peak incidence between the ages of 20 and 50.

About 85 per cent of kidney stones are made up of calcium oxalate. Crystals form when there is a super-saturation of calcium and oxalate in the urine. Insufficient water intake — one of the many risk factors — increases concentration of these stone-forming substances in the urine.

For Mr Lee, chronic dehydration could have possibly been one of the contributing factors of the disease. The former service engineer, who repaired heavy machinery, used to hate drinking water.

“If I was thirsty, I would drink gassy drinks,” he said.

Such cases are not uncommon.

Dr Lee, who noted an increase in kidney stone cases among foreign nationals who work in the construction industry in the last five years, said that people who work outdoors or live in tropical climates are more susceptible to the condition. “(These people) think they are drinking enough but actually lose more fluids than they replace,” he said.

Other risk factors include family history and gender — men are three times more likely to develop this condition than women are. A high-animal protein and high-salt diet also increases the risk.

You can prevent this condition with a few lifestyle changes. Dr Tan Yeh Hong, a consultant at Singapore General Hospital’s department of urology said it can be as simple as maintaining your fluid intake to avoid dehydration.

Foods rich in citrate such as oranges, grapefruit and lemons can also naturally inhibit stone formation, he added.

“People with a history of calcium oxalate stones should also avoid an excessive intake of oxalate-rich foods, such as spinach, beans, nuts and chocolates.” Also, go easy on the Vitamin C supplements,Dr Tan advised.

“Excessive Vitamin C (more than 4g a day) converts into oxalate, which may increase your risk of kidney stones.” - TODAY/ra