General Overview
Kidney stones are hard deposits of crystals (minerals and organic material) that form inside the kidney. They can just sit there for years without causing any problem, but can also cause severe pain (known as ureteric or renal colic) if they move into the ureter (pipe from kidney to bladder) and cause blockage.
They are an increasingly common problem and the global incidence is around 10% of the population. Although they most commonly affect males - estimated at 12% of men and 6% of women, that gap is narrowing. Other data from the UK suggests a lifetime prevalence of 13% with an average age of diagnosis of 49 years [1].
Symptoms
Often stones in the kidney cause no symptoms at all unless large. However they may cause an ache or pain in the loin/ flank and/ or cause haematuria (blood in the urine) and urinary infections.
Ureteric (or renal) colic is the characteristic sudden onset severe pain associated with a stone in the ureter causing obstruction to the kidney. This has been described as 'the worst pain imaginable' and on a similar level to childbirth. Often patients need to attend the emergency department, both for a diagnosis and pain relief. The pain may start in the loin and radiate around to the groin as the stone comes lower in the ureter. Once it reaches the level of the bladder, it may cause urinary symptoms with a constant desire to pass urine. Pain may also radiate into the genitalia. Ureteric colic is often associated with vomiting as well. Patients with previous stones may recognise this pain and take suitable pain relief and see if it will pass. It is important however to get checked out to make sure it was a stone and that it passes. Any patient who is unwell, or has a fever > 38 degrees should seek emergency medical attention as an infected obstructed kidney can be dangerous. [2]
Often the pain comes in waves and after the acute attack, the pain may completely subside. This is not a reliable sign that the stone has gone and often patients can have long periods without pain but still have an obstructed kidney. This is also why it is important to see a urologist to ensure the stone has passed to prevent long-term damage.
Management
-Ureteric stones. For small ureteric stones, often the doctor will advise a period of time to see if the stone will pass. Sometimes medications (called alpha blockers) are given to help stone passage although the evidence for this is controversial, but it is still recommended by guidelines for stones low down in the ureter. [3] However if the stone does not pass within a certain timeframe - usually 2-4 weeks - then treatment is recommended to clear the stone.
-Pain relief. The doctor will advise on this based on individual medical history and allergies. Often the best pain-killer for kidney stone pain is a non-steroidal anti-inflammatory (NSAID) medication. Examples include ibuprofen and diclofenac. Paracetamol is often used in addition. In the emergency department, if these medications do not work then stronger analgesia is given in through a vein (intravenous) with morphine to get on top of the pain.
-Kidney stones. Treating stones in the kidney will depend on the size of stone, anatomy of the kidney, number of stones, knowedge of previous treatment success and patient wishes. Small stones may not require treatment and can be observed. Larger stones are likely to need treatment and options include shockwave lithotripsy (ESWL), ureteroscopy (URS) or percutaneous nephrolithotomy (PCNL).
Prevention
It is important that all patients have a basic level of tests (urine and blood tests) to check their is no underlying cause. Young patients, or recurrent stone formers may be advised to have more complex tests with a 24 hour urine collection to look in more depth for underlying causes. Diet and fluid advice is vital for all patients. Occasionally the urologist may recommend a medical treatment (tablets) to reduce the risk of stone formation based on age, frequency of stone formation, stone type and underlying cause. More detailed discussion can be found on the 'prevention of stones' page.
The EAU patient information team have produced a webpage with more information on kidney stones that may be of interest. A pdf version can also be downloaded.