Developing kidney stones is a very common problem among people today - one in ten will experience kidney stones at some point in their lives. While they are called kidney stones, they are actually minerals deposits in the urine that have collected together to form larger crystals. Passing these crystals through the narrow urethra is what causes pain and discomfort when urinating.
Formation of Kidney Stones
Firstly, I would want to exclude an anatomical abnormality which can cause an obstruction and predispose to stone formation.
Normally, certain chemicals found in the urine prevent the formation of kidney stones. However, in cases of a chemical imbalance in the urine, mineral deposits in the urine can crystallise into larger substances.
There are various kinds of kidney stones based on the composition of minerals in the urine :
- Calcium stones - A result of excess oxalates, commonly found in some fruits, vegetables, chocolate and nuts
- Struvite stones - Caused by urinary tract infections and can grow to be quite large
- Uric acid stones - Chronic dehydration, gout and high-protein diets increase the risk of developing uric acid stones
- Cystine stones - Caused when kidneys excrete in excess certain amino acids due to a disorder
- Xanthine stones - Caused by an enzyme deficiency that causes xanthine buildup
- Silica stones - Rare and caused by certain medications and supplements
Signs and Symptoms You Might Have Kidney Stones
While tiny stones may pass through the urinary tract without problems, they can still cause uncomfortable, and sometimes painful, symptoms when they travel within the kidney and into the ureter such as :
- Pain in the lower part of the abdomen and groin
- Nausea and vomiting
- Unusual frequency and volume of urine
- Abnormal colour, cloudiness and putrid-smelling urine
- Hematuria, or the presence of blood in the urine
- Difficulty in urinating
You should always seek treatment immediately should you experience severe pain, fever, chills, vomiting and/or blood in the urine.
Kidney Stone Risk Factors
- Family and personal history of kidney stones
- Insufficient fluid intake or dehydration
- Urinary tract infection or obstruction
- High intake of salt, sugar, animal protein and foods high in oxalates and phosphates
- Metabolic diseases like cystic renal diseases, renal tubular acidosis, hyperthyroidism and gout
- Gastrointestinal diseases and surgery
- Certain medicines and supplements
How Our Diets Can Increase The Risk of Kidney Stones
One of the reasons for developing kidney stones is due to today’s high oxalate, animal protein and low citrate diet. 
Foods high in oxalate can be a predispose to calcium oxalate stones and food items like beets, spinach, chocolate and kale are high in oxalates. Excess uric acid in the urine, also known as hyperuricemia, can lead to recurrent uric acid stones. This is the case for patients with gout or uric acid-rich diet. Foods that contribute to the formation of uric acid include:
- Organ meats
- Red meat
- Fish and shellfish
- Green peas
- Dried beans
Citrate is an inhibitor of stone formation, and low levels in the urine predispose to stone formation. Foods such as lemon and lime are high in citric acid and can help boost the level of citrate in the urine, helping to reduce stone formation.
Treatment for Kidney Stones
For smaller stones, medication can be prescribed together with the requirement to drink 2-3 litres of water to help get rid of the kidney stone in the urine . Whereas for larger stones, a procedure called extracorporeal shock wave lithotripsy that uses “shock waves” can be used to break stones into smaller pieces so to pass them out in the urine. Patients will be sedated or administered mild anaesthesia during the treatment .
For kidney stones that are too large to be expelled through the urine, are trapped somewhere in the urinary tract, or are causing severe pain, surgery may be required. After the surgery, the patient may be given some dietary recommendations to avoid recurrence.
Preventing Kidney Stones
Staying well-hydrated and avoiding excess consumption of salt, animal protein and foods high in oxalate is helpful in preventing kidney stones from forming. A diet with a good amount of calcium is helpful as well, but be cautious with calcium supplements as hypercalcemia , where there is too much calcium in the body, can lead to not just kidney stones but also other problems.
Kidney stones are likely to recur, so patients who have recovered from it should take care to prevent it.
Dr Lincoln Tan is a urologist at Tan Urology, Gleneagles Medical Centre. He specializes in urologic cancer care and treatment. On top of his practice, he is also the chairman of the Singapore Cancer Society’s (SCS) Prostate Cancer Survivorship Advisory Panel.
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