Kidney stones explained

Kidney stones: the what, the why and the how

The symptoms of kidney stones may be alarming. These small deposits of salts and minerals formed within the kidneys may give rise to severe pain, affecting the side, back and lower abdomen. The impact of the stones is typically most evident when the patient needs to urinate: they often feel a frequent need to do so, while passing only a small amount of urine which may be cloudy, foul-smelling or pink in colour. Other symptoms include nausea or vomiting.

While this may bring about significant discomfort, treatment often entails little more than pain medication, along with the recommendation to up fluid intake so that the stone passes out with urine. It’s also reassuring to know that although it might hurt to pass the stone, it is unlikely that there will be lasting damage to the kidneys. That said, if the stone causes complications, or if it has become stuck inside the urinary tract, surgery may be required.

Risk factors

As with any medical condition, prevention is better than cure. In the case of kidney stones, prevention is focused on ensuring the health of your urinary system, from the kidneys to the bladder. This is because stones typically form when the concentration of urine increases, possibly because it contains substances like calcium, uric acid and oxalate, which tend to stick together. On the other hand, formation may be caused by the absence of substances which would prevent this crystallisation.

There may be several factors contributing to either of these conditions. For example, dehydration can play a role, along with a diet that’s high in protein and salt, both of which place strain on the kidneys.

Other risk factors include a personal history (if you have previously been diagnosed with kidney stones, it is possible that you will develop others) or a family history. Digestive diseases like chronic diarrhoea can change the way your body absorbs water and calcium, making it more likely for urine to crystallise, while conditions like frequent infections of the urinary tract, renal tubular acidosis and hyperparathyroidism can contribute, too. Supplements such as Vitamin C may also play a role in development, and medication (especially certain preparations to treat depression and migraines, laxatives and calcium-based antacids) may also be at fault. Finally, kidney stones have been associated with obesity and a high body mass index.

Different treatment for different stones

There are several different types of kidney stones. Calcium stones are the most common, usually occurring as calcium oxalate or calcium phosphate. While calcium oxalate stones are often associated with foods like nuts, chocolate and certain fruits and vegetables, or may be caused by high doses of Vitamin D, calcium phosphate stones are more likely to be caused by metabolic conditions like renal tubular acidosis, or medications containing topiramate, typically prescribed for migraines.

Struvite stones, on the other hand, usually occur in people who suffer from urinary tract infections. One of the problems with these stones is that they usually grow rapidly, often reaching a sizable mass, while patients experience few symptoms.

Uric acid stones are more often found in patients who have a genetic predisposition, although they are also often brought on by a drastic loss of fluid (as in the case of chronic diarrhoea). Diabetes is another common cause, as is a high protein diet.

Finally, people who suffer from cystinuria are likely to experience cystine stones, caused by the excessive excretion of an amino acid.

The type of stone presented impacts the treatment prescribed, which is why it’s important to identify the stone.

Prevention plan

The most effective way to prevent the formation of kidney stones is to remain well hydrated. It may also help to limit protein intake, and to reduce the consumption of foods containing oxalate. Finally, ask your doctor for guidance before taking supplements like Vitamin C or calcium.