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What are kidney stones?

Nephrolithiasis and urolithiasis are commonly referred to as kidney stones. Kidney stones are a common urological condition that affects people across various age groups. Kidney stones occur more frequently in men than in women, and often go unnoticed until they travel down the urinary tract, causing pain and discomfort during urination. While most stones pass without treatment, some cases may require medical intervention to prevent potential complications. If left untreated, kidney stones could result in loss of kidney function, increasing the risk of developing chronic kidney disease, and ultimately leading to renal failure.

In TCM, kidney stones are usually classified under shilin (石淋), characterised by the presence of stones in the urine, frequent and urgent urination, as well as severe pain in the lower back and abdomen.

How are kidney stones formed?

Our urine contains many different types of waste products. When the concentration of these products exceeds a certain threshold, crystals begin to form and attract other elements to create a solid mass, resulting in what we commonly known as kidney stones. Kidney stones are mainly classified into the following four types:

1. Calcium oxalate / Calcium phosphate

Calcium stones are the most common type of kidney stones, with calcium oxalate accounting for up to 70% and calcium phosphate constituting up to 20% of the cases. Elevated urinary oxalate levels may result from a diet high in oxalates or increased consumption of supplements such as vitamin C.

2. Uric acid

Elevated uric acid levels in the bloodstream can lead to the accumulation of uric acid crystals in the kidneys, resulting in uric acid stones. This is more frequently observed in people with gout, metabolic syndrome, type 2 diabetes and those who are obese. A high purine diet can also significantly increase urinary uric acid production.

3. Struvite

Struvite stones contain struvite (magnesium ammonium phosphate) and calcium carbonate apatite. They are less common and are usually associated with bacterial infections in the urinary tract. Females are more susceptible to struvite stone formation due to the higher incidence of urinary tract infection in women.  

4. Cystine

Cystine stones are caused by cystinuria, a rare inherited disorder which causes cystine to leak into the urine. People with cystinuria need to carefully manage their diet and lifestyle to reduce the risk of recurrent stone formation throughout their lifetime.

Symptoms

It is possible to be asymptomatic if the stone is small and non-obstructing. The following symptoms are likely to appear when larger stones move, causing irritation or obstruction to the urinary tract.

1. Sudden onset of pain
   • Pain is usually one-sided, and may start from the lower back below the ribs
   • Pain fluctuates in severity
   • Pain may radiate to the lower abdomen and pelvis
2. Increase urinary frequency or a persistent urge to urinate despite an empty bladder
3. Pain or burning sensation during urination
4. Decreased urine output
5. Blood in the urine
6. Nausea and vomiting
7. Fever, chills and lethargy when accompanied with infection
8. Sepsis (severe cases)

Treatments

Treatment of kidney stones largely depend on the size, type and location of the stone. Stones smaller than 5mm are usually able to pass by itself. Non-invasive procedures such as shock-wave lithotripsy may be used for larger stones. In certain cases, surgical intervention may also be required when the urinary tract is obstructed or when an infection is present.

Common herbs used to clear kidney stones in TCM

In TCM, the group of herbs commonly used to treat kidney stones is known as “san jin er shi” (三金二石). “San jin” (三金) refers to the Christina Loosestrife herb (金钱草), Japanese climbing fern spore (海金沙) and gizzard lining (鸡内金), while “er shi” (二石) refers to Talcum (滑石) and Pyrrosia leaf (石韦). Collectively, these herbs possess diuretic properties that aid in heat-clearing and elimination of dampness.

Prevention

One episode of kidney stones usually predisposes patients to further episodes. It is therefore important to determine the underlying cause of your kidney stones and take the necessary precautions to reduce the risk of recurrent stone formation.  

1. Maintain adequate fluid intake — Aim to drink 5-3L of water everyday to help dilute and flush out stones.
2. Incorporate citrus into your diet — Citrus fruits contain citric acid, which can bind to and help eliminate urinary calcium.
3. Reduce sodium consumption — Foods such as potato chips, processed meats, and sports drink are high in salt and can increase urinary calcium leakage, thereby elevating the risk of developing another stone.

Dietary precautions

1. Calcium stones

• Limit the intake of oxalate rich foods such as spinach, beetroot, nuts, rhubarb, sweet potato, black tea, and chocolate
• Avoid carbonated drinks as they contain phosphoric acid which promotes calcium oxalate formation

2. Uric acid stones

• Reduce the intake of purine-rich foods such as organs, red meat, spinach, mushroom, legumes, and seafood
• Reduce intake of sugary foods and drinks, especially those containing high fructose corn syrup
• Reduce consumption of alcohol
• Increase intake of fresh foods and vegetables

I have been diagnosed with calcium stones, should I reduce my dietary calcium intake?

Contrary to popular belief, a low dietary calcium intake may increase the risk of kidney stone formation. Calcium present in the digestive tract binds to oxalate, thereby decreasing the absorption of oxalate into the bloodstream and into the kidneys to be excreted. As such, it is important to maintain a normal dietary calcium intake.

Conclusion

Kidney stones are a common yet potentially preventable condition that can cause significant discomfort and complications if left untreated. Understanding the different types of stones, their risk factors, and associated symptoms is essential for timely diagnosis and appropriate management. Adopting healthy lifestyle habits, such as maintaining adequate hydration, reducing excessive sodium intake, and following stone-specific dietary recommendations, can significantly lower the risk of recurrence. Whether through conventional medical treatment or complementary approaches such as Traditional Chinese Medicine, early intervention and preventive care play a key role in protecting kidney health and improving long-term outcomes.

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