Notes to visitors
Kidney Stone Centre
The prevalence of urinary tract stone disease is increasing over the last decades. As of 2012, 10% of men and 7.1% of women in the United States are affected by kidney stone, a 70% increase from 1994. The incidence in Southeast Asia is even higher than that of the western counterparts. Patients with acute renal colic contribute to a significant percentage of emergency department visit.
Our Kidney Stone Centre was a comprehensive centre for the treatment and prevention of kidney stone diseases. The aims of the centre are:
- Provide efficient management of acute and elective urinary stone problems
- Facilitate the prevention of kidney stone in the long term
- Educate the public on kidney stone disease
Our multi-disciplinary team including urologist, nephrologist and dietician provide a single point of care for patient suffering from acute or recurrent kidney stones. Our staff are committed to provide the highest standard of care according to international guidelines.
We treat kidney stones using the latest minimally invasive procedures such as extracorporeal shock wave lithotripsy, ureteroscopy and percutaneious nephrolithotomy. Our centre was equipped with state-of-the-art equipments such as Dornier shock wave Lithotripter, Holmium laser, flexible ureteroscope and ultrasound lithotripter.
Apart from surgical treatment, the other important aspect is to prevent stone recurrence. We provide metabolic evaluation of every stone patient. We work hand-in-hand with dieticians and nephrologist to make individualised plans for recurrence prevention.
Location: Clinic H, 1/F, Tower B
- By appointment
- Every Tuesday 3:00pm – 5:00pm ;
- Every Wednesday 9:00am - 12:00nn;
- Every Saturday 9:00am - 11:00am
- 24-hour emergency assessment
- Please view here for information
- Initial: HK$1,200- HK$1,500
- Follow Up: HK$800- HK$1,000
Remarks: The above charges refer to doctor consultation fees only and exclude fees for other procedures, medication, laboratory services, etc. The total charge is subject to the attending doctor's discretion and depends on the patient's condition. Details on ancillary charges are available at the Admission and Cashier Counters.
About Kidney Stone
Over the last century there has been a global increase in the number of reported kidney stones. It is estimated that one in ten people will have a kidney stone at some time in their lives.
The lifetime risk of kidney stones is about 10% in men and 7% in women. In men, the first episode is most likely to occur after age 30, but it can occur earlier. Other diseases such as gout, diabetes, and obesity may increase the risk for kidney stones.
Although urine may look like a simple fluid, it's actually a complex liquid that contains hundreds of chemicals and minerals. If the minerals become supersaturated, they precipitate into crystals and grow into gravel, then stones. Supersaturation and stone formation occur if excessive amounts of a mineral are excreted into the urine or if the volume of urine is decreased by dehydration.
Around 90% of the time, the principal mineral in a kidney stone is calcium usually in combination with oxalate but sometimes paired with phosphate or other substances. Less often, kidney stones are composed of uric acid (5-10%) or struvite (5-15%). In rare cases, they contain other chemicals such as cystine or even certain medications.
- Calcium stones
Around 90% of kidney stones contain calcium either as calcium oxalate or calcium phosphate. Nearly 80% of all kidney stones are composed of calcium and oxalate.
- Uric acid stones
Uric acid is produced when the body breaks down protein. Urine becomes saturated with uric acid when it becomes more acidic (pH<5.5). People who consume high animal protein (meat) diets are more likely to form uric acid stones. Gout, chemotherapy, and disorders with high turnover of cells (e.g. myeloproliferative disorders) are also risk factors for these stones.
- Struvite stones (infective stones)
Struvite stones are composed of mixtures of magnesium, ammonium, phosphate and calcium carbonate phosphate crystals. These stones develop as a consequence of recurrent urinary tract infections. Some urinary bacterial can split the urea in the urine to form ammonium and also to make urine alkali. Struvite stones can grow very large, filling the contours of kidney - these are known as staghorn stones due to their shape.
- Cystine stones
Cystine stones account for only 1% of all kidney stones. They are due to a rare inherited genetic condition that results in high levels of cystine in the urine. There stones can occur in childhood.
Stones that form in the kidney can grow slowly and cause no symptoms. However, when they "drop" out of the kidney and into the ureter, the thin muscular tube draining from kidney to bladder, they can cause three major problems.
It is called renal colic and it is one of the most intense of all pains. Renal colic is caused by obstruction of the flow of urine and pressure builds up in the kidney. The pain often radiate along the path of urinary tract, beginning high in the back over the kidney and travelling to lower abdomen, groin and even into the genitals. The pain begins suddenly and quickly becomes unbearable quickly. Renal colic is often accompanied by nausea and vomiting. When a stone arrives in the lower urinary tract close to the bladder, it can cause urinary frequency, urgency and dysuria.
- Haematuria (blood in urine)
The haematuria associated with kidney stones can be visible to the naked eye or found to contain large number of red blood cells under a microscope (Microscopic haematuria).
When a stone lodges in the ureter, it blocks the flow of urine. Pressure builds up in the kidney, causing it to swell with fluid, a condition known as hydronephrosis. Permanent damage may occur if the obstruction is prolonged. Silent blockage of the kidney could result in the loss of kidney function.
Diagnosis of kidney stone disease
Confirmation of the diagnosis requires radiological imaging. The following imaging modalities may be used:
- Plain X-rays (also known as KUB-Kidney-Ureters-Bladder)
- X-rays with intravenous contrast (Intravenous urogram)
- Non-contrast CT scan (computed tomography)
Many studies have now demonstrated that non-contrast CT is the best imaging method to detect even the smallest stones. Ultrasound are not quite as good, but because they don't use radiation, they are the first choice for children and pregnant women. The old standard, intravenous urogram, is rarely used in modern practice.
Other necessary tests at the time of presentation include:
- Evidence of infection (fever, urinalysis)
- Kidney function
- Blood levels of calcium and urate
- Stone analysis
Selected patients with recurrent stone formation may require an extensive metabolic work-up with 24-hour urine collection and analysis. This can help doctors determine how best to prevent recurrent stone formation. The metabolic evaluation should be delayed until four to six weeks after acute stoned event has resolved.
Treatments of kidney stone
Depending on the stone size and location, kidney stones can be treated by a number of methods:
The first step is to relieve pain. Oral medications, such as nonsteroidal anti-inflammatory drugs is the treatment of choice. Some may require injections of powerful painkillers, such as narcotics.
The next step is to dislodge the stone so it will pass in the urine. Fluids can help flush the stone out. 68% of stones less than 5mm will pass spontaneously, but the rate falls to 47% for stones that are 6 to 10mm.
Medical expulsive therapy: medications such as alpha-blocker can relax smooth muscles in the ureter, thus increasing the chance of spontaneous stone passage.
This is the treatment of choice if you have small kidney or ureteric stones. The stone is located using X-ray imaging or ultrasound scanning. While you are lying down, a machine called lithotripter sends targeted shock waves to break up the kidney stone into pieces small enough to be passed naturally. Sometimes you will experience pain as the stone fragments pass. This procedure is usually performed under anaesthesia as a day case.
If the stone is stuck inside the ureter, a narrow instrument called ureteroscope can be passed up through the bladder and into the ureter. The stone is broken into dust using Holmium laser. For kidney stones that have not responded to ESWL, a small flexible ureteroscope can be passed to the kidney to break the stone. These procedures are usually done under general anaesthesia. A ureteric stent (a soft tube) may need to be inserted after the procedure.
Large stones may need to be surgically removed from the kidney. The surgeon make a small cut in your back and uses a telescopic instrument called nephroscope to break the stone up with shock waves or an ultrasound machine. The procedure is done under general anaesthesia, and you will usually need to stay in the hospital for a few days post-operatively.
For a rare minority of patients, the risk of stones is due to metabolic problems that need specific evaluation and treatment. For the majority of stone formers, genetic and environmental factors inter-related to change the risk of stone formation.
It has been estimated your genetic background is responsible for around 50% of the risk of kidney stones and there is not much you can do to alter this. However, the other 50% of the risk is due to environmental factors such as diet, fluid intake and obesity.
Advice can be tailored for individuals but below is some general advice that will help most stone formers to reduce their risks of formal stones:
Being overweight is a significant risk factor for kidney stones. Several studies have demonstrated that patients with increased body mass index have a higher risk of stones. Obesity also makes stones harde to treat: there are greater risks of having anaesthesia and it is more difficult to target stones with lithotripsy.
Most people are dehydrated. As we lead increasingly busy lives, live in air-conditioned/heated environments, loses water during exercise and long haul flights we are chronically dehydrated.
Increasing fluid intake has been shown to reduce stone recurrence. Aim for 2-3 litres a day, your urine should be colourless rather than orange or dark yellow.
Diet also contribute to your risk of stone formation. For your general health and risk of kidney stone formation, you should have a well-balanced high fiber diet. This means the diet should include fresh fruits, vegetables, diary product and whole grain products. You should limit your meat consumption (<100g/day) as animal protein is a risk factor. Finally a diet low in salt is important.
For more details, please click here to view our diet advice for stone formers.