Kidney Stones Urinary Tract Stones
Your kidneys are 2 bean shaped organs, each about the size of your fist. They are located near the middle of your back, just below the rib cage, one on each side of the spine. Our kidneys filter about 180 litres of blood a day, producing between 1.5 to 2 litres of urine. The purpose of this filtration is to extract the waste and extra water from the blood which becomes urine and flows to your bladder through the tubes called ureters.
The bladder then stores the urine which we empty on an average 3 to 4 times a day depending on the fluid intake. Renal stones are common, being present in 1 in 10 of the population. Average lifetime risk is around 5 to 10%. Men are more commonly affected than women, with the male to female ratio of 3:1. Peak age for developing stones is between 30 to 50 and recurrence is common.
What is a kidney/urinary tract stone?
A kidney stone is a solid piece of material that forms in the kidney out of the substances in the urine. Once the stone is formed it may stay in the kidneys in one of the small pockets called calyces without causing any pain or discomfort. A small stone up to a few millimetres may pass easily through the tube and out of the body without causing any pain or discomfort. However larger stones over 5 mm may get stuck in the ureter and cause blockage and severe pain and discomfort.
How Common are Kidney Stones?
Kidney stones affect approximately 10 to 12% of men and 5% of the women.
How Do Kidney Stones Develop?
The formation of kidney stones is a complex and multifactorial process. Kidney stones can form when substances like calcium oxalate, cysteine or uric acid are at high levels in the urine. Stones can also form if these substances are at normal levels, especially if the amount of urine made each day is low. These substances form crystals which then become anchored in the kidney and then gradually grow in size forming larger kidney stones. The majority of smaller kidney stones can pass without any problem. However once they reach a large size they can either cause blockage to the tube joining the kidney with the bladder or grow within the kidney to a very large size called staghorn stones, leading to recurrent infections, pain and discomfort in the flank and back area.
Symptoms of Kidney Stones
Pain is the most common symptom of kidney stones. This pain could be severe in case of a blockage to the kidney leading to renal colic which is a spasmodic pain in the flank radiating down to the groin. On the other hand stones sitting in the kidney can lead to intermittent discomfort in the back.
The presence of kidney stones can lead to passage of blood in the urine which could either be visible or picked up on a dipstick test on microscopic examination of the urine.
Recurrent Urinary Tract Infections
Large stones called staghorn stones, more common in females, can lead to recurrent symptoms of infection with loin pain, frequency and burning of urine. In more severe cases this could lead to serious infection of the kidney, pyelonephritis, which can cause high grade temperature with shivering and generally feeling very unwell. Urgent clinical help is required in these cases.
Asymptomatic Kidney Stones
Many people may carry kidney stones which are not causing any blockage and thus have no symptoms. These stones may be picked up during routine imaging for another pathology.
Investigation for Kidney Stones
- Computerised Tomography (CT scan). A plain CT scan is one of the most helpful investigations in diagnosing kidney stones. Just plain CT scan without the need for contrast helps in knowing the size, number, position and extent of obstruction these stones may be causing. This helps in planning further management and deciding the type of treatment required to treat these stones.
- Ultrasound scan. An ultrasound scan can also be used to detect kidney stones although smaller stones in the kidney or ureter may be missed. However as there is no exposure to radiation it can be used in children, younger females or pregnant ladies.
- Plain X-ray (KUB). Plain X-ray is a basic imaging which helps in identifying the stone and following up patients after treatment.
- Urine and blood tests. You may also require baseline urine tests to rule out infection. A blood test called urea electrolytes is checked to know your kidney function, along with calcium and uric acid levels.
Treatment of Urinary Stones
- Initial management of acute presentation. If you develop sudden severe flank pain radiating to the groin associated with symptoms of nausea, vomiting or temperature go to the nearest Accident & Emergency.
- After initial assessment you will be provided with pain control which is either in the form of injection, tablet or rectal suppository to control your pain.
- You have a urine test to rule out any infection.
- Bloods are checked to assess your kidney function and white cell count which is raised in infection.
- Imaging includes either a plain X-ray along with ultrasound scan or plain CT scan to rule out stone obstruction, along with any associated infection.
Plan of Treatment
- If your urine and bloods are normal and stone size is less than 4 mm you are most likely to pass the stone and treatment is mainly conservative. You may be sent home with some oral analgesia and a review appointment in the stone clinic.
- However if the stone is bigger than 5 mm leading to obstruction of your kidney you will be admitted to the hospital. Any obstruction is relieved either by putting a plastic tube through the bladder into the kidney under general anaesthesia, or a nephrostomy tube can be inserted directly into the kidney under local anaesthesia by one of the X-ray consultants. Once the obstruction is relieved you will be allowed home with a plan to book you electively for telescopic examination and laser treatment of this stone.
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