Half of all people affected by kidney stones will develop further stones within seven years. Kidney stones occur more frequently in young to middle-aged men. People living in a hot climate have a higher chance of developing kidney stones if they don’t drink enough fluid to replace that lost through sweating. Some individuals may inherit a predisposition towards the condition.

HOW IS IT DIAGNOSED?

Your doctor may suspect kidney stones after taking your medical history. Then you may be referred for further investigations, including a plain X-ray and/or intravenous orography, to sdentifs’ the presence and location of stones. Some kidney stones are made from calcium salts and show up well oil images. Other stones, made from oxalatc, phosphate or uric acid, can be more difficult to see. More tests may he done on urine to cheek for secondary infection, any presence of blood in the urine and to measure kidney function.

TREATING KIDNEY STONES

Treatment for the condition depends on the size of the stone.

• Small stones may pass with rest, plenty of fluids and some appropriate pain relief. Occasionally smaller stones may become lodged in the ureter, and these can he removed during examination with an instrument called a cystoscope.
• Larger stones call more problems. They may not pass spontaneously and are more likely to become lodged in the kidney. These stones are usually treated through a process known as lithotrupsy. This method uses high-energy shock waves to break the stones down into a powder, which can then be expelled in the urine.
• In some cases, stones have to be removed surgically, although this is rare and generally only used as a last resort.

SIGNS AND SYMPTOMS

Small stones may cause no symptoms whatsoever. However, larger stones are usually very painful because they cause the ureter to go into acute spasm. This is known as renal colic and the symptoms of renal colic are:

1. Intense pain that radiates from the back (usually on one side) to the groin. Sometimes it can be felt in the genitals as well.
2. Frequent, painful urination.
3. Blood in the urine.
4. Nausea and vomiting.

Renal colic subsides as soon as the offending stone is passed. An episode of renal colic may be an isolated incident. but some people are more prone to the condition and they may experience repeated attacks of kidney stones and renal colic.

PREVENTING KIDNEY STONES

• Drink plenty of fluids, approximately 2-3 litres (3Ii.-5 pints) a day.
• Increase your fluid intake during hot weather and after exercise.
• Avoid too much rhubarb, spinach and asparagus, as these promote the formation of oxalate stones.
• Check with your doctor in case you should limit your intake of calcium- rich substances, such as dairy products or calcium-based antacids.
• People who are prone to kidney stones may be advised to avoid, or reduce their consumption, of dairy products such as buffer and cheese.

Urine is 95 per cent water and 5 per cent uric acid, urea, salts (such as sodium, potassium and chloride) and creatinine. The nephron is part of the filtration unit through which the blood passes in the kidneys. Through this filtration system useful substances are reabsorbed into the bloodstream, and waste substances become urine, which is eventually passed from the kidneys by the ureter.

The urinary system is a sophisticated filtration unit which maintains fluid and chemical balance within the body. Many chemical reactions occurring in cells all over the body produce unwanted by-products and the kidneys filter these from the blood and excrete them in the form of urine.

The urinary system is made up of a pair of kidneys, two ureters, a bladder and a urethra. As well as their important excretory function, the kidney’ s also produce hormones that control red blood cell production and help to regulate blood pressure.

The kidneys are the main organs of the urinary system, with many vital functions:

• Removing toxic waste products from the blood and excreting them as urine.

• Returning useful substances to the bod^y‘s circulation.

• Regulating water balance. Your kidneys conserve water at times of relative dehydration and eliminate any surplus.

THE KIDNEY IN DETAIL

Your kidneys arc about 12 cm (5 in) long and 6 cm (2.5 in) wide and are at the back of ^your abdomen, just in front of your spine. The kidne^y has several regions, each with a different function:

• The cortex – This outer layer houses filtering units called nephtons.

• The medulla ^-The next inner layer is full of cone-shaped urine-collecting ducts.

• The renal pelvis -This is at the heart of the kidney and is where urine collects before passing on to the bladder.

FILTERING THE BLOOD

Blood is transported to each kidney through the renal arteries.

These blood vessels stem from the body’s main artery, the aorta, and carry a rich blood supply, that accounts for a quarter of the blood pumped b^y the heart.

Blood passes from these arteries through a sophisticated filtration system. The principal unit of the system is the nephron, which is made up of a glomerulus and a renal tubule.

PASSAGE OF URINE

Once fluid reaches the end of the renal tubule it is urine. Urine from the fleplirofls travels via collecting ducts in the kidney’s medulla to storage areas that feed into the renal pelvis. Each kidney is drained by a ureter, which is a thin muscular tube about 30 cm (12 in) long. Ureters carry urine to the bladder, which stores the urine until it is emptied. The bladder has a highly folded lining that smoothes out as it expands and fills with urine. A healthy adult excretes 0.5-2 liters (1-3 pints) of urine every day.