Kidney stones (kidney stone disease, nephrolithiasis) are hard deposits of mineral salts that form in the calyces and pelvis of the kidney when the urine becomes too saturated with them. They can be as small as a grain of sand or fill the entire collecting system of the kidney.
This is one of the most common urological conditions – roughly one person in ten has at least one stone during their lifetime, most often during their working years, and men are affected more often than women.
Small stones often go unnoticed for years until they move and cause renal colic. Early diagnosis allows them to be removed with minimally invasive methods and lowers the risk of new stones.
What kidney stones are
Urine contains dissolved salts – calcium, oxalates, phosphates, uric acid – and substances that stop them from crystallising, mainly citrate and magnesium. When this balance is upset, crystals settle out, stick together and gradually grow.
By their composition, stones fall into several types:
- calcium oxalate – the most common type, hard and cannot be dissolved with medicines;
- calcium phosphate – more common with alkaline urine and some metabolic disorders;
- urate (uric acid) – with acidic urine, gout, obesity and diabetes; with the right treatment they can dissolve;
- infection (struvite) stones – grow quickly in chronic infections with certain bacteria and can fill the whole renal pelvis like coral;
- cystine – rare, caused by an inherited metabolic disorder.
The composition determines both the treatment and the prevention, so it is always worth having a stone that you have passed or that has been removed analysed.
Symptoms
A stone that sits still in the kidney often causes no symptoms or only a dull heaviness in the lower back. Problems start when it moves into the ureter – the narrow tube leading to the bladder – and blocks the drainage of urine. Then you may have:
- sudden, very severe pain in the lower back or side, which spreads to the lower abdomen, groin and genitals and comes in waves – this is renal colic;
- nausea and vomiting;
- blood in the urine – visible or found only on testing;
- frequent, burning urination when the stone is close to the bladder;
- restlessness and being unable to find a position that eases the pain.
Some signs mean you should not wait for a booked appointment: a high temperature and shivering together with the pain, urine stopping altogether, constant vomiting that stops you keeping fluids down, pain that does not respond to painkillers, or an attack when you have only one kidney. In these cases go to an emergency department straight away or call 112 (the European emergency number) – a blocked and infected kidney is a life-threatening condition.
Causes and risk factors
The main cause is concentrated urine. When you drink little, work in the heat or sweat heavily, salts crystallise more easily. Other factors include:
- a diet high in salt, animal protein and sugar and low in fruit and vegetables;
- being overweight, diabetes, gout and high blood pressure;
- conditions in which more calcium or oxalate is passed in the urine – for example an overactive parathyroid gland or chronic bowel disease;
- repeated urinary tract infections;
- narrowings that slow the drainage of urine;
- long periods of immobility and some medicines and supplements in high doses;
- stones in parents, brothers or sisters, and a previous episode – the strongest predictor of a new stone.
Diagnosis
The kidney stone consultation at Dr Penev’s practice in Plovdiv or Karlovo begins with a detailed conversation about your pain, blood in the urine, temperature, previous stones, diet, fluid intake and the medicines you take. This is followed by an examination of the abdomen and lower back.
Ultrasound is the first imaging test: it shows stones in the kidney, swelling of the renal pelvis when there is a blockage, and the state of the bladder. Stones in the ureter, however, are often hidden from ultrasound, so if one is suspected a low-dose computed tomography (CT) scan without contrast is arranged – the most accurate method, which shows the size, position and density of the stone.
The laboratory tests needed are a urine test for blood, crystals and infection, and blood tests for kidney function, calcium and uric acid. If you have repeated stones, Dr Penev recommends analysis of the stone’s composition and a metabolic test of 24-hour urine, which reveals why the stones are forming.
Treatment
The choice depends on the size and position of the stone, your symptoms, whether there is infection and blockage, and the condition of the kidney.
Waiting and helping the stone pass on its own
Most stones smaller than 5–6 mm pass on their own within a few weeks. During this time you take painkillers, drink enough fluids and often an alpha-blocker – a medicine that relaxes the ureter and makes it easier for the stone to pass. A follow-up ultrasound or X-ray shows whether the stone is moving on. Urate stones can be dissolved with medicines that make the urine more alkaline.
Shock wave lithotripsy (ESWL)
For stones in the kidney up to about 2 cm and in the upper part of the ureter, shock wave lithotripsy breaks up the stone with shock waves through the skin, without an incision. The fragments are passed in the urine over the following days and weeks. The method is not suitable for very hard stones, in pregnancy, with an active infection or with impaired blood clotting.
Endoscopic treatment
Ureteroscopy (URS) is the main method for stones in the ureter and for smaller stones in the kidney: a thin instrument is passed through the urethra and bladder up to the stone, which is broken up with a laser and removed with a small basket. For large or staghorn (coral-shaped) stones, percutaneous nephrolithotomy (PCNL) is used – access to the kidney through a small opening in the skin of the lower back. After endoscopic operations a ureteric stent is sometimes left in for a short time – a thin tube that keeps urine draining while the swelling settles.
Dr Penev performs endoscopic stone treatment at the Department of Urology at Kaspela University Hospital (UMBAL Kaspela), Plovdiv, while the diagnosis, preparation and follow-up appointments take place at the practice. Open surgery is rare today.
When to see a urologist
Book an appointment if you have lower back pain that keeps coming back or gets worse when you move, blood in the urine even once, frequent and painful urination with no clear cause, repeated urinary tract infections, or if a stone has been found on an ultrasound done for another reason. Have a check-up also after a stone has passed on its own, to make sure the kidney is clear.
Prevention
Without a change in habits, roughly half of patients form a new stone within a few years. The most effective measure is the simplest: drink enough fluids throughout the day to pass 2–2.5 litres of pale urine. Cut down on salt and processed meats, do not overdo animal protein, eat more fruit and vegetables and keep to a healthy weight. Calcium from food should not be restricted – it binds oxalates in the gut. For some types of stone Dr Penev also prescribes preventive medication based on the metabolic tests. You will find detailed advice in the article on diet and fluids for kidney stones.
Kidney stones are a well-understood condition that today is treated without large incisions and, with the right prevention, often does not come back. If you have lower back pain, blood in the urine or already know you have a stone, book an appointment with Dr Penev in Plovdiv or Karlovo for a consultation and ultrasound.
Frequently asked questions
How do I catch the stone when it passes?
On the days when you have pain, pass urine through a fine sieve or gauze. Keep the stone you catch dry in a clean container and bring it to your appointment – analysing what it is made of shows which measures will protect you from a new stone.
Is it dangerous to live with a stone that doesn't hurt?
A small stone that stays still in the kidney can be monitored with an ultrasound scan once a year. Some of these stones, however, grow or start moving down the ureter, so if the stone is growing, if you have infections, only one kidney or a job in which a sudden attack would be risky, Dr Penev may recommend planned removal.
What kind of anaesthesia is used for stone procedures?
Shock wave lithotripsy is usually done with pain relief and light sedation. Ureteroscopy and percutaneous nephrolithotomy are performed under spinal or general anaesthesia, which the anaesthetist chooses according to your state of health.
How long does recovery take after endoscopic stone removal?
After ureteroscopy the hospital stay is usually one or two days, and you return to light everyday activities within a few days. After percutaneous surgery the stay is a little longer. If a stent has been left in, it may cause urgency and mild discomfort until it is removed.
Can stones permanently damage the kidney?
Yes, if they block the drainage of urine for a long time or cause repeated infections. That is why even a painless stone that is making the kidney swell must be monitored and treated in good time.
The information on this website is for general education and does not replace an examination and consultation with a doctor. If you have urgent symptoms, seek medical help immediately or call 112.