Medical Conditions
Most people with kidney stones do NOT have a medical condition causing the stones. This is called IDIOPATHIC stone disease and accounts for most of the kidney stones seen in the Western World.
There are a few medical conditions which are sometimes associated with a higher risk of forming kidney stones.
Hypercalcaemia
High calcium levels in the blood (not urine). This has nothing to do with eating too much calcium and is most often due to an abnormal parathyroid adenoma – a benign growth in the neck which interferes with normal calcium regulation. If a parathyroid adenoma is isolated as the cause of high calcium levels, surgery to remove the adenoma is usually required.
Other causes of hypercalcaemia include some cancers, immobility, sarcoid, some medications (Lithium), excessive intake of calcium supplements and rare hereditary disorders.
It is important to note that many patients with high levels of calcium in the urine (which can cause kidney stones) do NOT have hypercalcaemia (high levels of calcium in the blood).
Uric Acid Pathology
High levels of Uric Acid in the urine can cause Uric Acid stones. This may be associated with gout or high levels of Uric Acid in the blood.
Hyperuricosuria refers to elevated levels of Uric Acid in the urine. This may occur for no particular cause (idiopathic) or related to various conditions including obesity, gout and some malignancies.
Hyperuricaemia is where there are elevated levels of Uric Acid in the blood. This may be picked up on a blood test. Uric acid crystals may form in joints (gout), in the skin or in the kidneys.
Surgery for Obesity
This is increasingly recognized as a cause of kidney stones. Surgery for obesity can change the way some chemicals are absorbed from the intestines and other times can be associated with dehydration. This is especially true in patients who have had gastric bypass and intestinal bypass procedures but may also occur in patients who have undergone gastric banding surgery.
Surgery for obesity has many health benefits and patients requiring this surgery should be made aware that they are at an increased risk for developing kidney stones.
Inflammatory Bowel Disease (IBD)
Inflammatory Bowel Disease (also known as IBD) – such as Crohn’s Disease and Ulcerative Colitis, is known to interfere with the biochemical makeup of urine and can increase the chances of renal stone formation. IBD patients may have diarrhoea leading to loss of fluids and important electrolytes which disturb the urine biochemistry. This is especially true of patients with IBD who have undergone intestinal surgery.
Recurrent Urinary Tract Infections (UTIs)
This is a not uncommon cause of kidney stones, especially in women. Some organisms which cause UTIs change the chemistry of the urine and cause stones. Bacteria such as Proteus, Klebsiella and Pseudomonas are particularly prone to be associated with renal calculi.
It is particularly important to treat kidney stones associated with UTIs, as bacteria often lodge within the stones and it is not possible to get rid of the infections completely unless the stones are removed.
Kidney stones associated with UTIs tend to be made up of different chemicals and may look different when imaged radiologically. The stones may also be larger and softer than the more common calcium stones.
Renal calculi associated with UTIs cannot be dissolved and need to be treated surgically to achieve complete stone clearance.
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