Conventional solutions

For a long time, the best approach offered to patients was surgery to remove large, painful stones. Smaller stones were, and still are, treated with a number of different types of drugs, such as the thiazide diuretic chlorthalidone, which reduces urine calcium concentrations. These drugs have a host of side effects, including hypotension (hence their use in the treatment of high blood pressure), impotence, skin rashes and photosensitivity. They also alter the body's balance of important minerals, such as potassium and magnesium, and may therefore, ironically, end up increasing the risk of stone formation (Acta Urologica Belgica, 1994; 62: 25-9). Another popular medication is calcium citrate, a highly soluble calcium salt whose formation decreases urinary concentrations of free calcium.

Within the last two decades, a form of ultrasound treatment known as extracorporeal shock wave lithotripsy (ESWL) has been used to shatter stones, making their fragments easier to "pass" through the urine. The treatment is performed on a day patient basis, with NSAIDs used for pain relief. Anti biotics are often given prophylactically since bacteria, which are found in more than 30 per cent of stones, can be released into the kidney when the stones are shattered, increasing the risk of post procedure infection (Acta Urologica Jap, 1992; 38: 999-1003).

Although hailed as a revolution in the treatment of kidney stones, the risks of ESWL are probably underestimated. Most patients experience internal bleeding, which can range from a tiny haemorrhage to major bleeding requiring transfusion. Immediately after the procedure, blood flow to the kidneys can be drastically altered; usually it declines, but in about 8 per cent of cases blood pressure in the kidney rises, causing kidney hypertension (RH Hepinstall, Pathology of the Kidney, Boston, Massachusetts: Little, Brown & Co, 1992: 1592).

There is evidence that ESWL can affect the ability of the kidneys to filter out impurities efficiently (J Endourol, 1994; 8: 15-19). Other studies have shown irreversible kidney damage from the procedure (Nephron, 1993; 63: 242-3) and there has been one case of fatal kidney failure afterwards (Lancet, 1994; 344: 757-8). Damage to the kidney is reportedly in the range of 63 to 85 per cent (Am J Radiol, 1985; 145: 305-13; Radiology, 1987; 163: 531-4).

But perhaps most dispiriting of all is that ESWL doesn't cure the problem. In a French study, computed tomography scans performed two years after a group of patients had undergone lithotripsy showed that 40 per cent had a recurrence of stones and 25 per cent had scarring (Nephrologie, 1993; 14: 305-7).

This recurrence rate is not much different from what you could expect if you never had the procedure. In an observational study of the natural history of stone formation among 2,322 men, 42 per cent of patients experienced a recurrence of kidney stones (Acta Med Scand, 1975; 197: 439-45). Perhaps even more interesting was that 94.5 per cent of all stones passed spontaneously, suggesting that the need for aggressive medical action may be overstated. These researchers concluded that environment played a greater part in stone formation than family history an important point when considering treatment since there are so many beneficial changes in diet and lifestyle which those at risk can make.

Environmental factors

A number of environmental influences contribute to the risk of stone formation. People living in, or even just visiting, a warm or hot climate have an elevated chance of developing kidney stones (Med Trop, 1997; 57: 431-5; Am J Epidemiol, 1996; 143: 487-95). A sunny climate means greater risk of dehydration and lower urine output. This leads to an imbalance in urine volume and the concentration of those compounds which form stones.