A kidney stone is the result of tiny crystals sticking together in urine to form a lump large enough to cause severe pain when urinating. It can also cause other problems like bleeding and damage to the kidney.
Low volume, highly concentrated urine contributes to the supersaturation of elements normally found in the urine. When the solute exceeds the solvent's ability to dissolve it, precipitation of crystals can occur.
For people who have had a kidney stone the recommendations is to increase fluid intake to achieve 2 liters of urine a day. This can decrease stone recurrence by at least half.
There are five main types of kidney stones:
- Calcium oxalate stones (the most common type): Patients with calcium oxalate stones should limit the overall intake of oxalate-rich foods. These foods include beets, chocolate, coffee, cola, nuts, rhubarb, spinach, black tea, and wheat bran. Patients with calcium oxalate stones should also limit sodium intake; High-sodium diets are associated with greater calcium excretion in the urine
- Calcium phosphate stones: Calcium phosphate stones typically occur in patients with metabolic or hormonal disorders such as hyperparathyroidism and renal tubular acidosis. Patients with calcium phosphate stones are treated with citrate.
- Struvite stones: Struvite precipitates in alkaline urine, forming stones. Struvite stones are potentiated by bacterial infection that hydrolyzes urea to ammonium and raises urine pH to neutral or alkaline values.
- Uric acid stones: They're commonly seen with gout or those going through chemotherapy, and may result from certain genetic factors. Patients with uric acid stones should try eating less red meat.
- Cystine stones (the less common): Cystine stones are more likely to occur in people whose families have a condition that results in too much cystine in the urine (cystinuria)
Most stones with a diameter of up to 0.5cm will be expelled spontaneously when the patient urinates without requiring any active intervention. Stones that do not pass on their own are removed with lithotripsy or an endoscopic technique.