SUNDAY MAGAZINE

Common in the young

KIDNEY stones are a common problem, often affecting men between the ages of 20 to 40 years more commonly than others. The reasons for stone formation are often complex and not always discernible, despite elaborate investigations. A family history of stones, urinary tract infections, some metabolic disorders and ingestion of certain medicines can lead to stone formation.

A stone in the kidney is an aggregation of crystals that separate from the urine and build up to varying size. Normally, urine contains certain inhibitors of crystal formation, but these are not always effective in their preventive role in some individuals. The most common types of stones are: calcium oxalate, calcium phosphate and struvite stones which are infection related stones. Uncommon and rarer varieties also exist.

Tiny stones may be asymptomatic and pass through the urinary stream unnoticed. Larger stones cause intense episodes of pain as they move downwards via the urinary tract, in an attempt to be expelled during urination. Irritation of the lining of the kidney, the ureter or bladder can lead to the presence of blood in the urine. If there is associated infection, fever and episodes of shivering accompany the pain. Natural resolution by passing of the stone is not universal and in some, the stone fails to pass, usually because it is too large and causes complications such as blockage of the urinary tract, infections and kidney damage.

Stones are diagnosed by analysing the urine in a patient with these complaints. Imaging studies help to locate the site of the stone and also give pointers to a urologist as to whether one may reasonably expect the stone to pass naturally or whether intervention will become necessary. In some instances, further investigation may be needed.

In the majority of instances, stones are treated conservatively. Pain killers and drinking plenty of fluids is usually treatment enough. By straining all the urine passed (into a fine cloth or a fine mesh tea strainer), the stone is retrieved and sent for analysis. In others where the stone does not or cannot pass naturally, other options exist. These include:

Extracorporeal Shockwave Lithotripsy, where shock waves are directed at the stone from the outside to break up the stone into fragments which will subsequently pass naturally.

Percutaneous Nephrolithotomy, where an instrument called the nephroscope is passed into the kidney via a tiny incision to retrieve the stone.

Ureteroscopy, where a telescope-like instrument is passed via the bladder into the ureter to retrieve the stone.

Open surgery may be required in some instances.

All these techniques have inevitably, their own advantages, disadvantages and indications for use in a given patient.

Once a kidney stone forms, prevention of further stone formation becomes paramount. According to the stone type, advice may be given on diet, drugs, drinking plenty of fluids etc.

This advice will have to be individualised to suit each patient. But, preventive measures are not always successful and stone formation may be a recurrent phenomenon.

Dr. UMA KRISHNASWAMY

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