What are kidney stones?
Kidney stones are a build-up of crystals in the kidneys that form hard lumps, which in turn can cause pain and problems in the urinary system.
Kidney stones are fairly common and affect around 15% of men and 10% of women during their lives.
Small stones can be as tiny as a grain of sand and may remain in the kidneys without causing any symptoms. Pain can occur as stones get bigger.
Some stones may be as big as a golf ball. If the stone moves around or gets stuck in the kidney or ureter, this can cause pain.
Kidney stones can also cause infections.
Problems with kidney stones are most common between the ages of 30 and 60.
Types of kidney stones
Kidney stones are classified by the substance that forms them. The main types of kidney stones are:
- Calcium stones
- Struvite stones
- Uric acid stones
- Cystine stones
Depending on the type, stones may be harder or softer, bigger or smaller, and more or less likely to cause pain or infections, and the treatment may differ.
Symptoms of kidney stones
Although the stone is in the kidney or ureter, pain from the stone or any infection is usually felt elsewhere.
The symptoms of kidney stones include:
Seek urgent medical attention if there's fever, quickly worsening pain with or without chills or shaking.
What causes kidney stones?
Causes of kidney stones include:
- Not drinking enough fluids every day (dehydration)
- Some medications causing substances to build up in the kidneys
- Following a high-protein, low-fibre diet
- Family history of kidney stones
- Kidney infection
- Kidney disease
- Urinary infections
- Previous kidney stones
- Having only one kidney working
- Digestive system bypass operations
- Crohn's disease and other digestive conditions
- The genetic condition hypercalcuria causing extra calcium in the urine
- Overactive parathyroid gland affecting calcium in the body
- Some cancers, chemotherapy treatment for cancer
- Cystinuria, a condition affecting acid in the urine.
Diagnosis of kidney stones
A diagnosis of kidney stones will be based on the symptoms, medical history and tests, including:
- Urine tests
- Testing for stone type of any stones or fragments passed in urine, this can be collected in an old pair of tights or in a piece of gauze
- Blood tests for kidney problems
- CT scan
- Ultrasound scan
- Intravenous urogram (IVU), intravenous pyelogram (IVP), enhanced X-rays taken after special dye is injected into the arm
Treatment of kidney stones
Treatment may not be needed, especially if stones are small enough to pass in the urine.