What is a kidney stone?
A kidney stone is a solid mass made up of tiny crystals that can form in one or both kidneys or the tubes that connect the kidneys to the bladder. Kidney stones can form when certain chemicals in the urine become concentrated enough to crystallise and can bind together and grow into larger stones.
In most individuals, smaller stones will pass out of the body in the urine on their own. Larger stones may require medical or surgical intervention if they become stuck in the ureter or kidney and cause persistent problems.
What causes kidney stones?
Several factors can cause kidney stones to form, including:
- Dehydration: Not drinking enough fluids can cause your urine to become concentrated, allowing substances to crystallise and form stones.
- Diet: High levels of certain substances in the diet, such as oxalate, salt, animal protein, and vitamin C, can increase the risk of kidney stone formation. If you’re thinking about changing your diet, or have any dietary concerns, you should consult a healthcare professional.
- Medical conditions: Some medical conditions, including urinary tract infections can contribute to stone formation.
- Genetics: A family history of kidney stones increases the likelihood of stone development.
Different types of kidney stones
Kidney stones come in a variety of size, shape and colour. The main types of kidney stones are:
- Calcium: The most common type
- Struvite: Typically formed in response to an infection such as a urine infection
- Uric acid: Formed when there are high levels of uric acid in the urine often due to a diet high in purines.
- Cystine: a hereditary condition caused by a genetic defect.
Kidney stone symptoms
Small kidney stones may not cause any symptoms and may pass without causing pain or discomfort. However, larger stones or those that block the ureter may lead to various symptoms, including:
- Pain in the side and back
- Pain in the lower abdomen and groin
- Painful urination
- Frequent urge to urinate
- A high temperature
- Cloudy and bad smelling urine
How are kidney stones diagnosed?
Diagnosing kidney stones usually involves several steps:
Medical history and physical examination: Your doctor will ask about your symptoms, family history, and any underlying health conditions.
Biochemical analysis of any stones you pass in your urine
Urine and blood tests: These tests may identify high levels of the substances that can form stones and detect any underlying health conditions.
Kidney stone treatment
Treatment for kidney stones varies depending on the size, type, and location of the stone:
- Small stones: Often pass on their own with increased fluid intake and medication from your GP.
- Large stones: May require surgery to remove them
- Extracorporeal shock wave lithotripsy (ESWL): Uses sound waves to break stones into smaller pieces that can be passed in the urine without needing surgery.
- Ureteroscopy: A thin scope is inserted through the urethra (tube leading to the bladder) to locate and remove or break up the stone.
- Percutaneous nephrolithotomy: A surgical procedure where an incision is made in the back to remove the stone.
How to prevent kidney stones
Please consult with your healthcare provider for specific advice, but here are some general tips that may help prevent kidney stones:
- Stay hydrated: Drink plenty of fluids, especially water, to dilute substances in urine that can form stones.
- Diet modifications: Depending on the type of kidney stone, reduce your intake of salt, animal protein, and foods high in oxalate. Increase consumption of fruits and vegetables. Consult a medical professional before making changes to your diet.
- Medications: Certain medications can help prevent the formation of stones in people who are at higher risk. Consult with a doctor before taking any medication.
Reviewed Oct 2024
“This new knowledge will help healthcare providers to give better advice to patients.”
Dr Sarah Howles
Researcher spotlight
Dr Sarah Howles and her team used data from the UK Biobank – a collection of health and genetic information from around 500,000 participants – to investigate the link between fat and kidney stone disease.
Their research results suggest that carrying excess fat around your middle (often referred to as an ‘apple’ body shape) increases your risk of kidney stones by raising blood calcium levels.
The team are now working on understanding exactly how body fat can change blood calcium levels as knowledge of these pathways will open the door to developing new treatments to prevent kidney stones from forming.
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