Sunday, June 16, 2002		Fitness

A jugful of water a day will keep kidney stones away
B.K. Sharma

STONES get formed in two systems of the body — urinary excretory system, including the kidney, ureter and bladder, and the biliary system, including the gall bladder and bile ducts. Both have one thing in common that they excrete fluids containing various crystalloids which can precipitate and form stones. Kidney stones are very common, often recurrent, and produce one of the severest pain in the form of renal colic. Roughly 10 per cent of the adults, more commonly males, form kidney stones in their lifetime and many of them would form more stones after the detection or extraction of the first stone. They are common in the hot and dry climate referred to as the stone belt in the south-east states of the USA and the northern and some southern states of India.

Kidney stones can manifest themselves through blood or infection in the urine. Renal colic is the most dramatic presentation of the disease that needs emergency treatment, often requiring strong pain killers.

In case the stone disease persists for a long time, it can damage the kidneys on a permanent basis, leading to chronic renal failure needing dialysis or transplantation.

The kidney is the master chemist of the body and is assigned a very important role of regulating the water and salt balance besides many other important functions like regulating blood pressure and producing certain hormones. In the process of formation of urine, the kidney has to balance the very important function of conserving water and excreting various substances which are not readily soluble in the water. Various physico-chemical factors keep these substances in solution form, but when this balance is disturbed some of these compounds settle down and start the process of stone formation. The stone which starts as a microscopic structure, can grow as big as an egg which can sometimes occupy the entire excretory part of the kidney and is given the exotic name of ‘staghorn stone’ because of its spiky shape.

The stones vary widely in shape, colour and composition. The commonest component of the renal stones are calcium salts in the form of calcium oxalates, phosphate or their combination (white in colour), followed by uric acid stones (reddish brown in colour) and cystine stones (lemon yellow in colour) and made of amino acid cystine. Magnesium, ammonium phosphate stones, which are formed in the presence of infection, and a very rare form of stones known as xanthine stones which are a precursor of uric acid. Out of these stones, calcium, cystine and phosphate stones can be seen in an ordinary x-ray but uric acid stone is not seen and thus can be missed.

Disturbances in the balance between the amount of urine formed and the amount of various crystals is the deciding factor in the start of stone formation. If the volume of urine is small, as in case of people who are habitual poor water drinkers, or if the concentration of these salts is higher than normal stones can be formed.

Various factors which increase the absorption of calcium from the intestine or those diseases which produce high blood calcium level or which produce higher concentration of calcium in the urine favour the formation of calcium stone.

Similarly, circumstances increasing formation of uric acid in the blood favours the formation of uric acid stone. Increased absorption of oxalate and aminoacid cystine would do the same in the case of oxalate and cystine stone.

Some of the diseases which produce these disturbances are genetic in nature and thus run in families. This particularly applies to high oxalate stone or uric acid stone formation. Tumour of parathyroid glands and other diseases affecting the bones can liberate a lot of calcium, leading to calcium stone formation.

Consumption of high amount of proteins, alcohol and some of the drugs can give rise to uric acid stones. Some of the chronic intestinal diseases can lead to excessive absorption of calcium or oxalate, leading to calcium oxalate stones.

But the common thread which runs in all these circumstances favouring stone formation is the habit of taking less amount of water or fluids in general by these individuals. Even in the presence of physical forces favouring formation of stones, adequate amount of urine would to a great extent prevent, the formation of stone.

The only treatment for a well-entrenched stone in the past was the routine cut and stich surgery. However, in modern technology, very small number of patients require surgery in the usual sense of the word. Stones can be broken with the help of strong shock waves known as extra-corporeal shockwaves, lithotripsy.

Stones are first broken into small pieces and then passed out in the urine. Such a delivery of these ultrasound waves can also be done into the kidney by making a small hole in the flank for breaking the stone.

Stones can be broken with the help of laser. Baskets and snares have been designed to pull out the stone from the bladder, ureter and in fact from the kidney itself. Only a very complicated stone would now need surgery for its removal.

Prevention is indeed the key to the stone disease. Even if a stone is once diagnosed and it is taken out by one means or the other, the chances of reformation of the stone are very high. In fact, it is estimated that these people are likely to form a stone every 2-3 years.

The most important preventive measure is the adequate amount of fluid intake to ensure at least 2 litres of urine. The importance of this simple and practically feasible measure cannot be over-emphasised. On an average, 3 litres of fluid would be required for this purpose. But in very hot climate or in presence of extreme physical activity, much larger amount would be needed.

Commonly used diuretic thiazide is helpful in the prevention of calcium stones. Good voiding habits and prompt treatment of chronic infection should be taken to prevent the start of stone formation.

In case of calcium stones, moderate restriction of calcium is indicated and the milk products being the main source of calcium, need some restriction.

However, in a recent study from Italy published in the New England Journal of Medicine in January this year, it has been suggested that restriction of salt and animal proteins is more beneficial than the restriction of calcium itself.

For the oxalate stones, restriction of dark green vegetables (e.g. spinach), cereals with husk, nuts, chocolate, coca, excessive tea, black pepper and Vitamin C is helpful.

In the uric acid stone formation, restriction of proteins in the form of meat products and pulses and intake of alcohol is helpful. But the life of patients with this group of stone formation has become easier with the availability of drug Allalopuronol which prevents the formation of urine acid. Certain drugs favouring the formation of uric acid stone should be avoided.

Recognition of underlying metabolic disorders of various kinds and appropriate measures taken will decrease the stone formation.

Specific medical treatment is indicated in the case of cystine stones. It needs to be remembered that the diagnosis of stone is not a one time event.

Stone disease is a long continuous process and preventive measures are absolutely essential to avoid recurrent pain, morbidity and removal by any means.