What Is A Kidney Stone?
A kidney stone is a solid piece of material formed in the kidneys from minerals in the urine.
Risk Factors For Stone Formation
- Diets high in animal protein, sodium, refined sugars and oxalate
- Arising from the kidney such as renal tubular acidosis or medullary sponge kidney
- Others such as hyperparathyroidism
If a stone moves from the kidney and into the ureter it obstructs the ureter. This causes sudden excruciating, intermittent pain that extends from the back to the groin. This is called renal colic.
Other symptoms associated with renal colic include:
- Blood in the urine
The key to diagnosis of a kidney stone is with a CT scan. Majority of kidney stones are visible on a CT scan. The scan can give information on size, location and composition of the stone. This information is then used to advise on treatment.
Treatment Of Kidney Stone
In the setting of renal colic the first priority is to relieve pain with pain killing medications. The medications that are commonly used are anti-inflammatories or opioid analgesics (eg: morphine).
If the stone is small (ie: less than 5mm) there is a good chance the stone will pass out by itself. In some cases medications can be given to assist with passage of stone. The most common group of medications used for expulsion of stones is called alpha-blockers.
Indications for surgery are:
- Significant obstruction
- Ongoing pain
- Urine infection
- Large size stone
Surgery options are:
Extracorporeal Shockwave Lithotripsy (ESWL)
It is a non-invasive technique designed to breakup stones. A shockwave is generated outside the body and aimed at the stone. The stone must be visible on plain X-ray for this treatment. Once the stone is broken up, the body must expel the stones by itself which can cause pain, may be incomplete and in the process may cause complications.
Laser stone fragmentation
This is by far the most common surgical technique used to treat stones. Under a full general anaesthetic a small instrument called ureteroscope is inserted into the ureter. The stone is seen using a camera and broken up into minute particles using a laser machine. This method is effective for all stone types and has excellent clearance rates.
To find out more about laser of stones Click Here.
After breaking up the stone it is common to leave a JJ stent in for 1 to 2 weeks to assist with passage of stone particles.
After 1 to 2 weeks the JJ stent is removed using a cystoscope under local anaesthesia.
To find out more about JJ stents Click Here.
Percutaneous Nephrolithotomy (PCNL)
This is a surgical technique where a track is created from the back into the kidney. The stone in the kidney is broken up and the stone fragments removed. This is a more invasive surgical technique with possible complications such as bleeding from the kidney. As a result this technique is most commonly used for large stones that occupy the majority of the kidney (staghorn stones).
How Can Kidney Stones Be Prevented?
Specific prevention measures depend on the type of stone.
General dietary and lifestyle measures are useful regardless of stone types. They include:
- Increasing total fluid intake
- Increasing citric acid intake
- Moderate calcium intake
- Limiting sodium intake
- Limiting animal protein intake
- Limiting consumption of cola soft drinks and alcohol
Uric acid stone
For people who have high levels of uric acid in their blood and hence urine taking a medication called allopurinol is useful in stopping future stone formation. Allopurinol stops uric acid formation in the liver.
A group of medications called Thiazide diuretics can be useful in inhibiting the formation of calcium containing stones. It is best to be reviewed by a renal physician prior to starting such medications.