Calcium is an essential mineral that accounts for 1.5–2 % of total body weight; an average adult therefore carries ≥ 1 200 g. Roughly 99 % is locked in bone and teeth, while 1 % circulates in blood, maintaining a dynamic equilibrium with the skeletal reservoir. Insufficient calcium causes growth retardation, osteoporosis, joint pain and muscular weakness. Modern nutrition holds that calcium should be supplied throughout life, especially for children, the elderly, post-menopausal women—and even stone-formers.

Nephrolithiasis is common after middle age. The traditional view that “high calcium intake begets stones” has been questioned. Ninety percent of renal calculi are calcium oxalate, yet结石 formation is now viewed as the net result of multiple factors: genetics, endocrine status, co-morbidities, obesity, parasites, food preferences and serum calcium. Four principal mechanisms are recognised: supersaturation, inhibitory activity, promotor activity and crystal retention. A large British trial found that subjects with the highest calcium intake had the lowest stone incidence. The real culprit is not dietary calcium but disordered calcium metabolism. When bone calcium is mobilised to blood, vascular smooth muscle contracts, small vessels spasm and “senile” hypertension may follow. In the kidney, oxalate concentration—not calcium load—drives crystallisation. If oxalate is abundant it will bind calcium released from bone and form new stones or enlarge existing ones even when calcium intake is zero. Restriction therefore offers no protection, whereas rational calcium supplementation is safe and necessary; otherwise the elderly lose bone mass and develop more severe osteoporosis.

Dietary calcium is the preferred source. Stone patients are encouraged to eat tofu, milk, yoghurt, small fish eaten with bone, shrimp shells and marine products—foods that supply protein along with easily absorbed, loosely structured calcium that resists crystallisation. Simultaneously, reduce high-oxalate items and exploit anionic competition: drink citrus-based beverages or eat fruit to provide citrate, which competes with oxalate for free calcium and limits insoluble calcium-oxalate deposition.

When dietary measures are insufficient, add a bio-active calcium preparation (pearl calcium, Ju-neng-calcium, Caltrate-D, Shen-yi active calcium powder) plus vitamin D to enhance intestinal uptake. Calcium gluconate and plain calcium carbonate are poorly utilised. The anion of bio-active calcium binds excess cations (Ca²⁺, Mg²⁺) in the renal tubule and carries them out as insoluble salts. Absorption also requires phosphorus in a Ca:P ratio of 3:2; milk, eggs, meat, fish and legumes supply phosphorus. A daily intake of 1–1.5 g calcium neither exacerbates stones nor harms kidneys and will improve osteoporosis. Intakes > 2 g may precipitate in the kidney. Alcohol and coffee should be limited during supplementation.

Finally, existing calculi should be removed when indicated, and prevention continued:

• Drink enough water to lower urinary supersaturation and wash out calcium oxalate crystals.
• Avoid or blanch high-oxalate foods (spinach, strawberry, amaranth, water-spinach stem, beet, black tea, chocolate, dried bamboo shoot, pickled vegetables).
• Pharmacological inhibitors—magnesium, potassium citrate, orthophosphate, exogenous acid mucopolysaccharides—further reduce stone recurrence.

Anesthesia is given during lithotripsy, so pain is usually minimal; however, colicky pain may appear later when stone fragments pass down the ureter. Therefore some discomfort is possible during the whole stone-removal process.

Main lithotripsy techniques:

1. Extracorporeal shock-wave lithotripsy (ESWL)
   • Suitable for renal stones ≤ 2 cm
   • Stones are localized by X-ray or ultrasound and fractured with focused high-energy shock waves; the resulting sand-like particles are voided with urine.
2. Ureteroscopic lithotripsy / stone extraction
   • Rigid or flexible scopes (flexible scopes preferred for renal pelvis or calyceal stones)
   • Used for radiolucent or ESWL-resistant stones < 2 cm; the scope is passed retrograde up to the renal collecting system, stones are fragmented and removed.
3. Percutaneous nephrolithotomy (PCNL)
   • Recommended for stones > 2 cm
   • Under X-ray or ultrasound guidance a needle tract is created from the skin through the renal cortex; nephroscopy is performed and stones are broken (ultrasonic, laser or pneumatic) and extracted.

In summary, although some pain can occur, it is generally tolerable. After any of these procedures generous fluid intake and frequent voiding are essential to help clear the fragments.

After extracorporeal shock-wave lithotripsy (ESWL), the time needed for stone expulsion depends on the size and hardness of the fragments. In most cases, passage begins only after one day; soft stones may be expelled on the same day.

Although ESWL can break the stone into pieces, these pieces are still discrete fragments. They have to be flushed out by drinking plenty of water and urinating frequently. The recommended fluid intake is 2 000–3 000 mL per day. Patients are also advised to walk around so that the fragments can migrate and be expelled more easily. A small portion of the fragments starts to come out one day after the procedure, and the bulk of the material is then passed gradually; in general, the majority of fragments clear within one day. Large or hard stones may not be completely disintegrated by a single session; a second lithotripsy one week later may be required, and only after the stone is reduced to fine gravel can complete expulsion occur.

During the passage period, mild abdominal pain and sometimes haematuria are normal; increasing fluid intake is usually sufficient.

Patients should rest for at least three days after extracorporeal shock-wave lithotripsy (ESWL); the exact period is adjusted according to how smoothly the stone fragments pass.

The repeated shock waves produce mild trauma to the kidney or ureter, leading to localized edema and sometimes small mucosal tears. This explains the slight abdominal pain or discomfort commonly felt after the procedure. Provided the symptoms are tolerable, no extra intervention is required.

Post-ESWL routine

• Drink plenty of water
• Perform gentle activity (walking) to help gravel descend
• Avoid strenuous exercise, which can intensify pain while edema is present

Minimum 3-day rest is advised. On the third day, if pain and hematuria have resolved, the patient returns for imaging:

• No residual fragments → resume normal work and life
• Residual stones → second lithotripsy session and a longer rest period

Additional advice: stay relaxed, and refrain from spicy or irritating foods.

In general, minimally invasive lithotripsy requires 5–7 days of hospitalization.

When extracorporeal shock-wave lithotripsy (ESWL) fails to clear the stones, minimally invasive lithotripsy is performed. This involves making a small puncture in the skin to insert a special instrument that delivers holmium laser energy directly onto the stone surface. The success rate is high because the laser effectively fragments most stones, allowing the fragments to pass out naturally.

For ureteral stones, a cystoscope can be passed through the bladder into the ureter to reach the stone, and holmium laser lithotripsy is then performed. Although effective, the procedure may cause minor trauma to surrounding tissues. Therefore, patients are typically hospitalized for 5–7 days post-operatively. During this period:

• Anti-inflammatory and anti-edema medications are administered.
• Urine color is monitored; if red blood cells are present, it indicates possible injury to the kidney or ureter, and the patient is advised to drink plenty of water and rest in bed.

If, after 5–7 days, the patient has no discomfort and urine returns to normal, they can be discharged.

Post-discharge instructions:

• Avoid strenuous exercise
• Drink large amounts of water to help flush out any remaining fragments.