A B C D E F G H I J K L M N O P R S T U V W

KIDNEY STONES

How do Kidney Stones occur ?

Stones may develop just because the urine is very concentrated. Not surprisingly, stones are therefore more likely to occur in hot climates. On the other hand, stones can occur because the output of a given chemical waste product is increased. Calcium stones occur when there is too much calcium in the urine. This may happen if there is too much calcium in the diet from milk, cheese or bread. Some people seem to absorb more calcium from the gut and there is nowhere for it to go other than into the urine. Other people may have an overactive parathyroid gland (hyperparathyroidism). This results in calcium being leached out of the bones and again it has nowhere else to go but the urine. More often, no obvious cause can be found. Oxalate stones can occur if there is too much oxalate in the diet (spinach, rhubarb, chocolates and certain nuts). They are more likely to occur in people who have a bowel problem in which fat is not being absorbed properly. Uric acid stones form when there is too much uric acid in the urine. This comes as a direct result of too much uric acid in the blood. This is particularly likely in people who are prone to the condition of gout. Cystine stones are an uncommon problem where the kidneys leak high quantities of a chemical called cystine.

Why do Kidney Stones occur ?

Quite a few of the chemicals concerned are produced as a result of an inherited tendency. Infection is likely to occur with stones irritating the lining of the tubes leading from the kidneys downwards. In turn, the infection makes it more likely for more stones to develop and existing stones to grow. Stones will also form more readily if for some reason the urine does not flow freely from the kidneys downwards. Stagnant urine makes it more likely for crystals to form.

Treatment Involved for Kidney Stones

An abdominal x-ray may show certain types of stones. A special kidney x-ray (intravenous pylogram: IVP or intravenous urogram: IVU) needs to be done to show the position of the stone and to find out if there is any blockage. This is done by giving an injection into the arm vein. Several x-rays are taken over the next 2 hours. This shows the stones in the kidneys, ureters or bladder. It will also show whether any stone is producing a blockage. It is also important to find out the chemical structure of the stone which has been passed. Further tests can be done by analysing a 24-hour urine sample. Exact amounts of calcium, oxalate, uric acid and cystine can be measured. A stone may not pass on its own. It may get stuck in the ureter. If it either blocks it or causes pain, the stone needs to be removed. This can sometimes be done by passing a tube into the bladder (cystoscopy) and trying to remove the stone from the ureter by means of a miniature basket. If the stone is stuck in the kidney or if the stones in the kidneys continue to get larger, then an operation may need to be done (percutaneous renal surgery). Alternatively, the stone can sometimes be broken up from the outside using high frequency sound (lithotripsy). Having treated the first stone, it is important to prevent further stones from being formed by drinking lots of fluid to keep the urine dilute. Up to 6 or 8 pints a day may be necessary. Calcium stones can be treated by reducing the calcium in the urine. This is achieved by reducing bread, milk and cheese. Tablets can also be used to cut back the calcium content of urine. Oxalate stones may be managed by drinking lots of fluid. A low oxalate diet does not always help, and correcting the underlying problem may be essential. Uric acid stones are prevented by taking allopurinol tablets. These lower the level of uric acid in the blood so that less appears in the urine. Cystine stones may be prevented by drinking more fluid and by additional chemicals which make the cystine more soluble.

During Treatment for Kidney Stones

A new stone can form without causing symptoms until it breaks away from the kidney and passes down the ureter. x-Rays done from time to time will show what is happening to existing stones and whether new ones are forming. Loin pain, pain on passing urine, blood in the urine or fever suggest that an infection has occurred. You must then contact your doctor. If infection is confirmed, antibiotics will be needed. Untreated infection can make stones grow more rapidly.

After Treatment for Kidney Stones

If a stone that is blocking a kidney is not removed, the kidney will shrink and stop working. If this happens to both kidneys, severe kidney failure may occur, needing artificial kidney treatment.

If Kidney Stones is Left Untreated

Some people pass only one stone in their life. If many stones form and if blockage to the ureters is frequent enough, there is a risk of developing kidney failure.

Effects on Family of Kidney Stones

Some types of stone are more likely to run in families. The doctor will advise if other members of the family need to be screened.