RENAL CALCULUS
The two kidneys are situated in the back of the abdomen. Their function is to remove waste products and unwanted water from the blood, in the form of urine. Urine passes away from the kidneys, down a tube on each side called the ureter, and into the bladder. From here, the urine is discharged through the urethra. If there is too much of certain waste products in the urine, these substances form crystals. Crystals can then combine to form stones. The stones may be happy to lie in the kidney, and often do not cause symptoms there. However, when they pass down the ureter on their way to the bladder, pain usually occurs with anything but the smallest stone. If a stone gets stuck on its way down the ureter, pain usually occurs in the form of renal colic. This is a griping pain which can be very severe. It is felt in the loin, and often spreads down to the groin. It is caused by the ureter trying to squeeze the stone out. The pain comes and goes in waves. Blood may be passed as well, due to the irritation of the lining of the ureter by the sharp-edged stone. As the stone is being passed, the pain may be felt in the penis (males) or in the vaginal area (in females). Once the stone has passed, the bleeding and pain stop quite abruptly.
TYPES
" common:
o calcium phosphate (8%)
o calcium oxalate (most common: 73%, most opaque)
o magnesium ammonium phosphate ("struvite")
" uncommon:
o diammonium calcium phosphate
o magnesium phosphate
" rare:
o cystine (faintly opaque; 1%)
o urate (lucent; 7%)
o xanthine
CAUSES
Almost 95% of all kidney stones are calcium stones. They occur when there is too much calcium in the urine.
A second type of kidney stone is made of uric acid. These stones are much less common than calcium stones. Uric acid stones occur because you have too much uric acid in your urine. They might occur if you have become dehydrated; for example, during strenuous exercise on a hot day or perhaps during an illness. Uric acid stones are common in people who have gout, a disease that causes high uric acid levels in the blood.
A third type, struvite stones, are not quite so well understood. It is thought that these stones form as a result of an interaction between protein-breakdown products and infection-causing bacteria in the urine.
Finally, a rare type of kidney stone is a cystine stone. It occurs if you have the genetic disease called cystinuria. This disease results from a birth defect that causes the kidney to allow too much cystine into the urine. This type of stone formation is almost always diagnosed during childhood
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.
PREVENTION
If you do not have any underlying health problems, the most important thing is to drink plenty of water daily. The goal should be to urinate from 2 to 4 liters per day. Make sure you avoid getting dehydrated.
There are no specific dietary recommendations until a stone from your system has been analyzed. After analysis your diet can be evaluated and any changes recommended.
SIGNS AND SYMPTOMS
Episodes of severe, colicky (intermittent) pain every few minutes. The pain usually appears first in the back, just below the ribs. Over several hours or days, the pain follows the stone's course through the ureter toward the groin. Pain stops when the stone is passed in the urine.
Blood in urine. Urine may appear cloudy or dark.
Episodes of nausea associated with renal colic.
Some people have no symptoms, until they pass gravel-like stones in the urine.
Kidney or urinary infection may be caused by the stone. In these cases, symptoms may be caused by the infection. These are fever, chills and backache.
RISK FACTORS
Decreased urine volume due to dehydration.
Improper diet (too much calcium).
Hyperparathyroidism, which causes high blood and urinary calcium levels.
Family history of kidney stones.
Gout, which is caused by high uric acid levels in the blood, and gives rise to uric acid stones.
Excess alcohol consumption.
Bed confinement for any reason
