KIDNEY STONES

Kidney stones will affect 10% of the population at some point in their lives. They can be extremely painful - trying to pass a stone is said to be on a par with childbirth! Click below to find out more about why they occur, how to prevent them, and how they are diagnosed and treated.

WHY DO STONES OCCUR AND CAN I PREVENT THEM?

DIAGNOSIS AND TREATMENT OF KIDNEY STONES

 

WHY DO STONES OCCUR AND HOW DO I PREVENT THEM?

Stones form usually because of an over-concentration of a substance in urine. This can happen if there is too much of a substance being released from the kidneys, or if the urine is just too concentrated due to dehydration. Occasionally, there is an inherited problem with the kidneys leading to stone formation, but this is relatively rare. Having had stones once, unfortunately there is a 50% chance of getting more in the future, so prevention becomes especially important.

Common stones are made of calcium, oxalate and phosphate. Others are made of uric acid (a breakdown product of proteins). Certain foods have high levels of each of these (see advice sheet below), but paradoxically cutting out one thing can make the other worse, so it's about moderation. Eating a well balanced diet without excessive salt or animal protein, normal levels of calcium and avoiding excess calcium in combination with vitamin D supplements (unless medically required) are all helpful, as it will reduce the amount of these key substances in your urine. Do not cut out calcium though, as this will increase levels of the more problematic oxalate salt in your urine.


Above all else though, the key is to stay well hydrated, particularly if you've been hot or sweating. At least 2 litres per day, focussing on water or dilute squash, perhaps lemon barley water, which contains citrate, a natural inhibitor of stone formation. If you've been exercising or sweating, this should be 3 litres. 

Occasionally, if you're forming lots of stones, and if following full evaluation a reason for this is identified, you may be offered tablet treatment to prevent stones growing. It is difficult and indeed impossible in most circumstances, to make stones re-dissolve once they have formed unfortunately.

Another less common group of stones are those related to recurrent urinary infections, where the bacteria causes ammonia production in the urine by breaking down urea (a waste product excreted in the urine). This makes the urine very alkaline, and causes struvite (also known as triple phosphate) stones to grow in the kidney. These are often larger and need surgical treatment.

The link below takes you to the British Association of Urological Surgeons advice sheet on stone prevention.

 

DIAGNOSIS AND TREATMENT OF STONES

Often stones have no symptoms, and are discovered incidentally on a scan. These commonly don't need treatment. If lying in the kidney they can produce low level or intermittent pain in the side under the ribs (the loin). However, stones more usually declare themselves as a sudden severe pain as they drop out of the kidney and the body tries to pass them out through the narrow tube which carries the urine to the bladder - known as the ureter. This is a muscular tube which propels urine, but when a stone is stuck, the contraction causes severe pain from the loin down towards the groin, said to be comparable to childbirth. Nausea, vomiting and sweating are often experienced. Depending on the size of the stone, many will pass by themselves, so you can consider waiting and trying simple painkillers such as ibuprofen / paracetamol if you are not too unwell. If you have a fever and or shivering though, you must seek immediate specialist attention, as if the kidney becomes infected and blocked, you will become septic (a severe infection) and need the problem resolved straight away to avoid long term damage to your kidney and possibly to you.

A CT scan is the best way to detect stones, unless you are pregnant (potential x-ray risk to the unborn child). It is very quick and will detect stones other scans will miss.

 

TABLETS AND SHOCKWAVES

If you're not in too much pain, and there's no other urgent need to treat your stone, you may be offered a period of time on tablets, including painkillers if necessary, and medication to relax the kidney tube (ureter) to allow the stone to pass. This is called medical expulsive therapy, and is preferable to an operation if possible. 

If the stone needs breaking up to pass, this can be done with strong shockwaves being passed from a machine from outside the body, through the skin to crack the stone. This is called extracorporeal shockwave lithotripsy (ESWL). This can save more major interventions and just takes a few minutes. 

URETEROSCOPY

If you're in too much pain or there is an urgent need to relieve the blockage, or if it simply looks like the stone won't pass, you'll be offered an operation where a telescope is inserted under a full anaesthetic into the bladder via the water pipe, and from there into the the ureter to reach the stone and fragment it with a laser. You may also need a temporary stent (a plastic tube left inside to relieve the pressure on the kidney) if there is swelling or it is impossible to get the stone first time round. This can then be returned to later. Success rates are generally high with these procedures (ureteroscopy), though there are risks of infection and pain for a day or two after.

 PERCUTANEOUS NEPHROLITHOTOMY (PCNL)

If you have larger stones in the kidney, which are too big to manage with shock wave treatment or ureteroscopy (see above), then occasionally a more direct approach to the kidney through the skin is required, a PCNL. This is more major surgery, with more risks attached, and would only be performed by a specialist in the technique.