Kidney stones are a relatively common problem, affecting around 1 in 10 people, usually between the ages of around 30 to 60 years old. They can develop in one or both kidneys. Kidney stones don’t usually cause any symptoms until the body tries to remove them from the body by passing them through the kidneys, into the bladder to be eliminated in the urine.
Some people don’t know they have them, since they can be very small and can pass in the urine without causing any symptoms. But kidney stones can also become much larger, meaning that passing them can be very painful.
Kidney stones can have various causes, and having a proper diagnosis can help doctors discover the cause, and create a treatment plan that can help to prevent them from returning.
Part of this diagnosis can mean having a kidney stones MRI scan. In this article, we’re going to discuss the causes, diagnosis and treatment for this potentially painful condition.
What are Kidney Stones?
The kidneys are a pair of bean-shaped organs, each around 10cm long and situated at the back of the abdomen, either side of the spinal column. Blood passes into the kidneys where waste products are filtered out and removed, allowing the clean, filtered blood to then travel around the body.
Each kidney is connected to the bladder via a tube called the ureter, and waste products travel through the pair of ureters to the bladder, where urine is formed. Urine (complete with waste products) then passes out of the body through a single tube called the urethra. Together, the kidneys, ureters, bladder and urethra form the urinary tract.
Sometimes, certain waste products can build up, especially if we’re dehydrated or we have certain medical conditions. These waste products can crystallize, leading to kidney stones. We’ll go into more detail in the Cause of Kidney Stones section below.
Symptoms
The symptoms of kidney stones include:
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Pain in your side
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Testicular pain in men
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Pain that comes and goes
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Feeling hot and sweaty, with a high temperature
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Nausea
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Vomiting
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Signs of a urine infection
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Blood in your urine
Sometimes, large kidney stones can cause a blockage in the ureter that can lead to severe pain and a kidney infection. Symptoms include:
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A high temperature
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Fever
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Chills and cold sweats
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Cloud or foul smelling urine
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Feeling weak
Not everyone will experience symptoms if their kidney stone is relatively small. Severe pain however is a medical emergency and you should seek medical help as soon as possible.
Can an MRI Scan Detect Kidney Stones?
A kidney stones MRI (magnetic resonance imaging) scan can detect kidney stones as part of a wider investigation into what’s causing your symptoms.
What Does it Look Like on MRI?
Kidney stones will appear as white irregular shapes within the kidney on an MRI image.
Limitations
A kidney stones MRI may not be able to detect the difference between uric acid stones and non-uric acid (we discuss these types of kidney stone in more detail further on). Also, the signal emitted from a kidney stone and picked up on an MRI scan may diminish fairly quickly, meaning that a kidney stone may appear as a non-specific dark void on an MRI scan. For these reasons, MRI scans are used in conjunction with other tests in order to diagnose kidney stones.
How an MRI Scan Detects Kidney Stones
An MRI scan uses strong magnetic fields and radio waves to create images of the inside of the body. Computer programming and trained professionals can then use these images to differentiate between healthy tissue and crystallized chemical build up and kidney stones.
Diagnosing Kidney Stones
If you think you may have a kidney stone, speak to your doctor as soon as possible. If your symptoms are severe, you may need emergency medical attention. Either way, there are a number of tests you will undergo in order to get a diagnosis of kidney stone disease.
Medical History Review
As well as asking about your symptoms, your doctor will take a full medical history from you, to ascertain if you have any other conditions and what your diet and lifestyle may look like. These kinds of questions may feel intrusive, but it’s helpful for your medical team to understand your chances of having kidney stones, so that treatment can begin as soon as possible.
Physical Examination
Your doctor will also use their hands to feel around your abdomen and back to gauge where your pain is coming from. This will help them to better rule or diagnose kidney stones.
Urine Tests
A urine sample can be used for a simple kidney stone detection process - specialist laboratory technicians will use a microscope and test strips to look for physical stones and signs of infection.
Blood Tests
You will also have a blood test that will check the levels of the chemicals in your blood that could be causing kidney stones, such as calcium and uric acid. Blood tests can also check how well your kidneys are functioning and if there’s any problems that could need further investigations.
X Ray
If your doctor thinks you may have large kidney stones, they may refer you for an abdominal X ray to confirm this. X rays can sometimes miss smaller kidney stones and for this reason, they’re not a common tool used in kidney stone detection.
MRI
As discussed above, a kidney stones MRI can be used to diagnose the condition and determine the shape, size and location of each stone, as part of a range of tests. An MRI scan may also be an option for pregnant women with suspected kidney stones that are too small to be detected via an X ray.
CT Scan
CT stands for computed tomography, and a dual energy CT scan (also known as a high speed CT scan) can be used to detect even the smallest of stones. This is useful in both the initial kidney stone detection and in determining if there may be more stones to pass.
Ultrasound
An ultrasound of the kidneys is a common, non-invasive and safe way to diagnose kidney stones. It’s very quick and can be useful if your kidney stones are causing you immediate and severe pain. An ultrasound is also used when pregnant women are suspected of having kidney stones, as a safer alternative to CT scans.
Stone Analysis
In some cases, your medical team will provide a strainer that you will need to urinate into, in order to catch each kidney stone as it passes. They can then be sent to a laboratory for analysis to determine what crystalized chemicals they’re made from. This can then be used to formulate a management plan to help prevent them from returning.
Specialised Tests
In some cases, a test called a retrograde pyelogram can be performed to check for blockages in the urinary tract caused by kidney stones. This is a type of X ray that uses an injectable contrast dye to improve the image quality to detect small stones and blockages.
Causes of Kidney Stones
There is no absolute cause of kidney stones, but a major factor in developing kidney stones is dehydration - not drinking enough water and clear fluids. If you’re consistently dehydrated, certain chemicals can build up in the body that can accumulate in the kidneys, crystallize and cause solid masses, or stones. Being dehydrated means that there isn’t enough fluid to dilute chemicals such as:
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Calcium
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Uric acid
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Struvite
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Cystine
Calcium kidney stones are the most common and are caused by a build up of calcium oxalate - a substance made by the liver and also found in crisps, peanuts, chocolate and spinach.
Uric acid stones can be caused by eating a diet very high in protein. Protein-rich animal-based foods contain high levels of substances called purines, which are broken down into uric acid during digestion. High concentrations of uric acid causes the urine to become acidic, and can lead to kidney stones. Those with gout also have high levels of uric acid in their blood, which can put them at a higher risk of developing kidney stones.
Struvite kidney stones can be caused by urine and kidney infections, and can develop relatively quickly.
Cystine kidney stones are less common, and can develop in people with a condition called cystinuria that causes the kidneys to excrete too much cystine, an amino acid, causing the urine to become too acidic.
Kidney stones in general can be very small (the size of a grain of sand and relatively undetectable) or much larger - potentially up to the size of a golf ball if left untreated.
Other than dehydration, there are some other factors that can increase your risk of developing kidney stones:
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Eating a diet very high in protein, and low in fibre
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Eating a diet high in salt
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Being obese
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Having recurrent urine or kidney infections
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Having a family history of kidney stones
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Having inflammatory bowel disease or chronic diarrhoea
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Having had gastric bypass surgery
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Being immobile or very inactive
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Taking certain medications, including those used to treat acid reflux, epilepsy, water retention and retroviruses such as HIV
Prognosis and Treatment
Getting a doctor to diagnose kidney stones is important so that you know what’s causing your symptoms. Treatment will depend on the size and location of each kidney stone.
Small stones in the ureter may pass with your urine undetected, or they may cause some pain and discomfort that can be managed with over-the-counter non-steroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen. They may take a couple of weeks to fully pass, and to help ease your discomfort, make sure you drink around three litres of water a day. Avoid drinking alcohol, fizzy drinks or too many caffeinated drinks and avoid salty foods to help stay hydrated.
Larger kidney stones may require medications called alpha blockers to help the stones pass through your urinary tract.
Very large kidney stones may require surgery to break them down or remove them, depending on their size and location:
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Shock wave lithotripsy - ultrasound and high frequency shockwaves are used to break the kidney stone down so that it can be passed in the urine.
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Uteroscopy - a long thin tube is passed into the ureter via the urethra to remove each stone, or break them down using lasers, under general anaesthetic.
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Percutaneous nephrolithotomy - a long thin tube is passed directly into the kidney through a small incision in the back to remove each stone under general anesthetic.
Either way, to help prevent kidney stones from returning, ensure you drink plenty of water and clear fluids each day. Your urine should be pale and the colour of straw. If it’s darker, then you could be dehydrated, so aim to drink more.
Find an MRI Scan for a Kidney Stones
If you’re concerned about having kidney stone disease, book a private kidney stones MRI scan so that you begin treatment or start making dietary changes if necessary as soon as possible. It can be difficult knowing if an MRI scan is the right scan for you, and if you’re unsure, one of our private consultants can help guide you towards the right decisions for your health.
References
Website, N. (2023b, May 17). Kidney stones. nhs.uk. https://www.nhs.uk/conditions/kidney-stones/
Kidney stones - Symptoms and causes. (n.d.). Mayo Clinic. https://www.mayoclinic.org/diseases-conditions/kidney-stones/symptoms-causes/syc-20355755
The Healthline Editorial Team. (2023, February 6). Everything you need to know about Kidney Stones. Healthline. https://www.healthline.com/health/kidney-stones
Kidney Stones. (2024, September 9). Cleveland Clinic. https://my.clevelandclinic.org/health/diseases/15604-kidney-stones
Ibrahim, E. H., Cernigliaro, J. G., Pooley, R. A., Bridges, M. D., Giesbrandt, J. G., Williams, J. C., & Haley, W. E. (2015). Detection of different kidney stone types: an ex vivo comparison of ultrashort echo time MRI to reference standard CT. Clinical Imaging, 40(1), 90–95. https://doi.org/10.1016/j.clinimag.2015.09.005
