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Renal Calculi (Kidney stones)

What are kidney stones?

The kidneys filter blood and remove the waste products and water to produce urine.

Kidney stones may form when there are high levels of minerals or salts in a person’s urine.

Stones may begin as small granules but can develop into larger stones to the degree whereby they can obstruct of fill the inner hollow portions of the kidney. Some kidney stones stay in the kidney and cause no problems while others travel down the ureter to the bladder and are passed out when you urinate. However if a kidney stone lodges in the ureter it can cause blockage to the flow of urine from the kidney and result in pain along with other possible complications.

Types of kidney stones

Calcium – the most common type of kidney stones, can be either calcium oxalate or calcium phosphate.

Uric acid – uric acid is a waste product that is produced with chemical changes in the body. Uric acid crystals don’t dissolve well in acidic urine and a by-product may be uric acid stone formation.

Struvite – uncommon, usually form in people with long term or chronic infections involving the urinary tract.

Cystine – rare, found in conditions where there are high levels of cystine in the urine.

Causes of kidney stones

In most cases the cause of why you have formed a kidney stone is unknown, men have a higher incidence rate than women.

  • Dehydration – dark concentrated urine and low volumes of urine create an environment where salts are not effectively dissolved.
  • Diet – calcium stones may form with high levels of calcium in the urine, however this doesn’t directly result from a high calcium diet. This more relates to how your body processes calcium. It is not generally recommended to reduce calcium intake however reducing salt intake is advised as too high a salt intake interferes with the reabsorption of calcium from urine back into the blood. Oxalate is a component of the most common kidney stones (calcium oxalate), eating food high in oxalate can increase your risk.
  • High acid levels – can lead to calcium oxalate and uric acid stone formation. Diets high in animal protein for example beef, chicken, fish, pork can raise body acid levels.
  • Medical conditions – uncommon however increased risk in people with medical conditions that result in high levels of calcium, oxalate, cystine or uric acid in the body.
  • Medication – certain medications used for treating conditions such as kidney disease, cancer or HIV can increase risk of stone formation.
  • Family history

Symptoms of kidney stones

  • Pain is generally the symptom of a kidney stone, this is commonly known as “renal colic” when a stone begins to move within the urinary tract. Sharp, cramp like pain which if felt in the back or side (loin) and may travel to the groin.
  • Urgent or frequent need to urinate
  • Blood in the urine
  • Nausea and vomiting
  • Symptoms of urine infection may include fever, sweating, chills, painful urination, cloudy or foul smelling urine.

Diagnosing kidney stones

The following tests are used to detect a kidney stone:

  • X-Rays
  • Ultrasound
  • CT Scans

Blood and urine tests may be used in finding a cause for kidney stone formation, while analysis of a kidney stone can determine its type.

Treatment for kidney stones

Treatment for kidney stones is based upon the location, type of stone, size and symptoms experienced.

In most cases kidney stones will pass through the urinary tract system on their own without the need for surgery. Treatment during this time may be pain relief for renal colic. In some cases the pain may be severe requiring hospitalisation for stronger pain relief.

If a kidney stone doesn’t pass and causes conditions whereby it is obstructing or blocking the flow of urine through the urinary tract, or is causing more serious situations such as bleeding or infection one of the following treatment options will be considered.

  • Extracorporeal Shock-Wave Lithotripsy (ESWL) – ultrasound waves are delivered in order to break the kidney stone into smaller fragments, which can then be more readily passed out in the urine. Generally used for kidney stones, which are less than 2cm in size.
  • Endoscopic removal – which involves inserting a very thin telescope up to through the urinary passage to the level of the stone. This is done under a General Anaesthetic. The stone is then broken up with a laser fibre and the fragments removed or washed out.
  • Percutaneous Nephrolithotomy – a surgical procedure whereby a small incision (cut) is made in your back and a special surgical instrument is used to remove the kidney stone.
  • Open Percutaneous Nephrolithotomy – a surgical procedure whereby a larger incision (cut) is required to gain access to the location and removal of the stone.