Kidney Stones
Figure 1: Diagram illustrating the areas of renal pain known as renal colic.
What is a kidney stone?
Kidney stones form when minerals or acid salts in your urine form crystals, which later become stones. Every person has a 5 to 10% chance of forming a urinary stone in their whole life with men more likely to form stones than women.
What are the symptoms of kidney stones?
Kidney or ureteral stones can block the normal urine flow through the ureter resulting in severe pain in loin and flank (renal colic - Fig. 1). This severity depends on stone characteristics – e.g. size, shape, and location of the stone.
The pain comes in waves and may be accompanied by other symptoms such as
Nausea
Vomiting
Blood in the urine (urine appears pink or red)
Painful urination
Fever
How are kidney stones diagnosed?
After a detailed medical history and physical examination further investigations are performed. Blood and urine tests will be requested and the diagnosis is confirmed with a CT scan (Ultrasound may be done for children, young adults or pregnant women). If your stone passes with urine the stone may be collected and analysed. If you have a high risk of forming more stones in future, you will get additional tests known as ‘metabolic evaluation’ to understand the composition of urine for potential preventive measures.
How are kidney and ureteral stones treated?
Figure 2: Cystoscopy and insertion of ureteric stent.
Renal colic is an emergent situation and you should contact your family doctor or nearest hospital to relieve the pain. In case of a fever, you must seek immediate medical help as this can be life-threatening situation.
If your symptoms settle and there are no indications for a ureteric stent insertion, you may be managed with medical expulsive therapy (MET). In MET you will be given tablets to help pass the stone and for pain relief. The best pain relief in renal colic is anti-inflammatory medication such as voltaren or ibuprofen. Occasionally, morphine-based analgesia may be needed for severe pain. A repeat scan in 3-4 weeks will be done to ensure you have passed the stone.
In some instances, you will require a cystoscopy and insertion of ureteric stent (Figure 2) where a camera is passed into your bladder under general anaesthetic and a tube inserted into the ureter to aid the flow of urine around the stone. If a stent can’t be placed, urine flow can also be established by inserting a tube into your kidney directly through the skin (a percutaneous nephrostomy).
Indications for such procedure are:
If your pain cannot be relieved adequately by medication
You have impaired kidney function
You have suspected urinary infection
You have a very large stone that is unlikely to pass without surgery
Once a stent is inserted, the definitive treatment options are:
Ureteroscopy / Pyeloscopy (insertion of a camera into the urinary tract via the bladder and fragment the stone with LASER)
PCNL (insertion of a camera into the kidney to fragment and remove the stone)
Dissolution of stone with tablets (suitable for small proportion of stones only)
There are many factors that influence the decision include:
Your symptoms
Your body features and general medical and medication history
Stone characteristics like its location, size, and hardness
Your personal preferences, social situation and occupation
How can kidney stones be prevented?
Some people are more likely to form stones than others. However, you can do several things to reduce your risk of having recurrent stones. Majority of these intervention revolve around maintaining a healthy lifestyle and diet. Specifically you should
Drink enough water to ensure your urine is clear or light yellow
Reduce intake of salt, processed food and meat, especially red meat
Eat lots of vegetables, fibre, and fruit
Maintain an active lifestyle and healthy weight
Make sure your diet contains a sufficient amount of calcium (2 serves of dairy)